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DISSERTATION

Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University

By

Miguel Archangelsky

The Ohio State University 1996

Dissertation Committee: Approved by

J. W. Wenzel Co-Advisl D. L. Denlinger C. Welty C. A. Triplehom Co-Adviser Department of Entomology UMI Number: 9630845

Copyright 1995 by Archangelsky, Miguel All rights reserved.

UMI Microform 9630845 Copyright 1996, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code.

UMI 300 North Zeeb Road Ann Arbor, MI 48103 Copyright by Miguel Archangelsky 1995 ABSTRACT

This is a taxonomic and bionomical study of the immature stages of the New World hydrophiloids. Most of the information presented here comes from specimens collected in the field and reared under laboratory conditions; this allows for unequivocal associations between immature stages and adults. Description of collecting and rearing techniques for coming from different habitats is discussed; also a general account of the biology of hydrophiloids is summarized. A generic key to larvae of all known New World hydrophiloids is provided, as well as diagnostic descriptions for each ; these descriptions include the egg cases, larvae, and pupae. Further information on number of species, distribution, species with known immature stages, and additional biological characteristics is provided for each genus. Detailed illustrations for each genus supplements the key and the diagnostic descriptions. The immature stages of five genera are described here for the first time: Notionotus, Oocyclus, , , and Pemelus. A phylogenetic analysis using characters from larvae, pupae, egg cases, and adults was conducted; the outgroups included , , and . Characters of the immature stages were obtained from the material studied, those from the adults were obtained from M. Hansen’s generic revision for the superfamily. The results support the position of Hydraenidae within the , and not as part of Hydrophiloidea; is proposed as the sistergroup of Hydrophiloidea. At a family level two clades are distinguished, the first one formed by Georissidae, Epimetopidae, and Helophoridae; the second one formed by , Spercheidae, and Hydrochidae. Larval characters are most informative at the base of the tree, especially the characters associated to the development of the spiracular atrium in the larvae; adult characters were more informative at the apex of the tree. To my parents and Don Johnston

“In the final years of the twelfth century, from twilight of dawn to twilight of dusk, a leopard looked upon some wooden planks, some vertical iron bars, men and women who were always different, a thick wall and, perhaps, a stone trough filled with dry leaves. The leopard did not know, could not know, that what he craved was love and cruelty and the hot pleasure of rending and the odor of a deer in the wind; and yet something within the choked him and something rebelled, and God spoke to him in a dream: You live and will die in this prison, so that a man I know may look at you a certain number of times and not forget you and put your figure and your symbol in a poem which has its precise place in the scheme of the universe. You suffer captivity, but you will have furnished a word to the poem. In the dream, God enlightened the rough beast, so that the leopard understood God’s reasons and accepted his destiny; and yet, when he awoke, he felt merely an obscure resignation, a gallant ignorance, for the machinery of the world is overly complex for the simplicity of a wild beast. Years later, Dante lay dying in Ravenna, as little justified and as much alone as any other man. In a dream, God revealed to him the secret purpose of his life and labor; in wonderment, Dante knew at last who he was and what he was and he blessed his bitter days. Tradition holds that on awakening he felt he had received and then lost something infinite, something he could not recuperate, or even glimpse, for the machinery of the world is overly complex for the simplicity of men.”

Inferno 1,32 JORGE LUIS BORGES Translated by Anthony Kerrigan ACKNOWLEDGMENTS

I would like to express my most sincere appreciation to my advisors Dr. John W. Wenzel, Dr. Charles A. Triplehom, and Dr. Don E. Johnston. Their support, guidance, criticism, and insight have been invaluable during my research. I would also like to thank the other members of the advisory committee, Drs. D. L. Denlinger C. Welty, Dana Wrensch and Dr. Dan Crawford. Many people have devoted their time and assistance during these past years, especially during my fieldwork, without them a lot of the information presented in this dissertation would have been difficult to gather; they are P. W. Kovarik, T. K. Philips, K. Stephan, R. Androw, and George Keeney. I am also indebted to A. F. Newton, D. L. Gustafson, C. Costa, L. Fem&ndez, M. Toledo, and P. Skelley for providing me with preserved specimens for this study. I have to thank several institutions: the INTA in Argentina, the people form UCV (Maracay), and Rancho Grande Biological Station in Venezuela, and the Archbold Biological Station in Florida. All of them provided me with support and permits in order to collect some of the specimens used in this study. The Ohio State University through the Graduate Alumni Awards, and the Tinker Foundation made possible my collecting trip to Venezuela. A special thanks goes for George Keeney for his assistance in rearing, the same goes for M. E. Durand. The illustrations that accompany this dissertation have been possible because T. L. Temple spend time teaching me different drawing techniques, and tactfully criticizing my artwork. My former colleagues from Argentina, especially Dr. A. O. Bachmann from the Museo Argentino de Ciencias Naturales Bernardino Rivadavia, and Dr. Ronderos from the Museo de La Plata, are responsible for my interest in entomology and aquatic . Don Johnston taught me a lot about how to conduct research, but the most valuable impression he left on me was his devotion to teaching; his continuous search for a level of excellence made him a great inspiration, and one of the better teachers I have ever known. Finally My most sincere thanks go to my parents, my sister, and the rest of my family for their support, patience and understanding. VITA

November 11, 1961 Bom - Buenos Aires, Argentina

1982 - 1986 B.A. Biology C.A.E.C.E. College Buenos Aires, Argentina

1987 - 1989 Researcher, Museo Argentino de Ciencias Naturales, Buenos Aires, Argentina

1990 - present Graduate Teaching and Research Associate, The Ohio State University

PUBLICATIONS

Refereed Publications

Archangelsky, M. 1985 (1987). Nota distribucional sobre Tropistemus (Tropisternus) scutellaris Castelnau 1840 (Coleoptera, Hydrophilidae). Revta. Soc. ent. Arg. 44(2): 168.

Archangelsky, M. 1989. A new species of the genus Phaenonotum Sharp, 1882 (Coleoptera, Hydrophilidae, ) from Venezuela. Aquat. Insects. 11(4): 217-220.

Archangelsky, M. 1990 (1991). El gdnero Phaenonotum Sharp en la Argentina. I. Redescripcidn de Phaenonotum regimbarti Bruch, 1915 y Ph. argentinense Bruch, 1915 (Coleoptera, Hydrophilidae, Sphaeridiinae). Revta. Soc. ent. Arg. 49(1-4): 157-164.

Archangelsky, M. 1992. El g6nero Phaenonotum Sharp en la Argentina II (Coleoptera, Hydrophilidae, Sphaeridiinae). Ubicacidn de Hydroglobus puncticollis Bruch, 1915 dento del gdnero Phaenonotum. Revta. Soc. ent. Arg. 51(1-4): 47-51.

vii Archangelsky, M. and M. E. Durand. 1992a. Description of the preimaginal stages of Dibolocelus ovatus (Gemminger and Harold, 1868) (Coleoptera, Hydrophilidae: ). Aquat. Insects. 14(2): 107-116.

Archangelsky, M. andM. E. Durand. 1992b. Description of the preimaginal stages of angustus Sharp, 1882 (Coleoptera: Hydrophilidae, Hydrophilinae). Aquat. Insects. 14(3): 169-178.

Archangelsky, M. and M. E. Durand. 1992c. Description of the immature stages and biology of Phaenonotum exstriatum (Say, 1835) (Hydrophilidae: Sphaeridiinae). Coleopts. Bull. 46(3): 209-215.

Archangelsky, M. 1994a. Description of the preimaginal stages of Dactylostemum cacti (Coleoptera: Hydrophilidae, Sphaeridiinae). Ent. scand. 25: 121-128.

Archangelsky, M. 1994b. Description of the immature stages of three Nearctic species of the genus Leach (Coleoptera: Hydrophilidae). Int. Rev. ges. Hydrobiol. 79: 357-372.

Archangelsky, M. and L. A. Fernandez. 1994. Description of the preimaginal stages and biology of Phaenonotum (Hydroglobus) puncticolle Bruch (Coleoptera: Hydrophilidae). Aquat. Insects, 16(1): 55-63.

Non-refereed Publications

Archangelsky, M. (1992). Underwater Trapping. The Ohio Coleopterist 1(2): 1-3.

Archangelsky, M. (1993). Hydrophilids; Habitats, Common Names and Their Biology. The Ohio Coleopterist 2(1): 2-4.

Archangelsky, M. (1993). Rearing Hydrophilids: a Few Problems. Mola, 2: 5.

Archangelsky, M. (1994). Short Notes on Hydrophilidae, I. The Ohio Coleopterist 3(1): 3.

FIELDS OF STUDY

Major field: Entomology

viii TABLE OF CONTENTS

Page

Dedication ...... iv

Acknowledgments ...... v

Vita...... vii

List of Tables ...... xi

List of figures ...... xii

CHAPTER 1 Introduction State of Knowledge of the Immature Hydrophiloidea ...... 1 Objectives...... 8 Systematic Position of Hydrophiloidea ...... 8

CHAPTER 2 Materials and Methods Collecting Techniques ...... 11 Rearing Techniques ...... 13 Study of Larval and Pupal Morphology ...... 19

CHAPTER 3 General Morphology of the Hydrophiloidea Egg Cases ...... 22 Larvae...... 23 Pupa...... 24

CHAPTER 4 General biology of Hydrophiloidea 29 CHAPTER 5 Systematic Section: A Revision of the Immature Stages of the New World Hydrophiloidea Key to the New World larvae of Hydrophiloidea ...... 35 Diagnosticic Descriptions ...... 44

CHAPTER 6 Phylogenetic Analysis of Hydrophiloidea Current Phylogenetic Hypotheses ...... 172 Phylogenetic analysis ...... 173 Discussion ...... 176 Conclusions ...... 182

APPENDICES Appendix A ...... 417 Appendix B ...... 420 Appendix C ...... 421 Appendix D ...... 427 Appendix E ...... 428 Appendix F ...... 430

REFERENCES...... 431 LIST OF TABLES

Table Page CHAPTER 1 Table 1. New World Hydrophiloidea; classification down to generic level, modified from Hansen (1991) ...... 2 Table 2. New World hydrophiloidea and state of knowledge of their immature stages ...... 5

CHAPTER 5 Table 3. New World Hydrophiloidea. Genera studied for this Dissertation ...... 36 LIST OF FIGURES

Figure Page

Figure 1 orientalist third instar . (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segment 9, dorsal view. Scale bars: A = 2 mm; B and C = 0.2 mm ...... 183

Figure 2 Helophorus orientalist third instar larva. (A) Right antenna, dorsal view. (B) Labroclypeus, dorsal view. (C) Labium, dorsal view. (D) Right mandible, dorsal view. (E) Right maxilla, dorsal view. Scale bars: 0.1 mm ...... 185

Figure 3 Helophorus orientalist pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. Scale bars: 1 m m ...... 187

Figure 4 Epimetopus trogoidest first or second instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 0.5 mm; C = 0.1 m m ...... 189

Figure 5 Epimetopus trogoidest first or second instar larva. (A) Left mandible, dorsal view. (B) Labroclypeus, dorsal view. (C) Left antenna, dorsal view. (D) Right maxilla, dorsal view. (E) Labium, dorsal view. Scale bars: 0.05 mm ...... 191

Figure 6 sp.t second or third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 9 and 10, dorsal view. Scale bars: A = 1 mm; B and C = 0.1 m m ...... 193

Figure 7 Georissus sp.t second or third instar larva. (A) Labro­ clypeus, dorsal view. (B) Right antenna, dorsal view. (C) Labium, dorsal view. (D) Right maxilla, dorsal view. (E) Right mandible, dorsal view. Scale bars: 0.05 mm ...... 195

xii Figure 8 Georissus sp.; second or third instar larva. (A) Left pro- thoracic leg, antero-lateral view. (B) Detail of abdominal sclerites. Scale bars: 0.05 m m ...... 197

Figure 9 rufipes; first instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Labroclypeus, dorsal view. (D) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 0.25 mm; B and D = 0.1 mm; C = 0.05 m m ...... 199

Figure 10 Hydrochus rufipes; first instar larva and egg case (H. squamifer). (A) Left antenna, dorsal view. (B) Left maxilla, dorsal view. (C) Egg case. (D) Labium, dorsal view. (E) Right mandible, dorsal view. Scale bars: A, B, and E = 0.05 mm; C = 0.5 mm; D = 0.025 mm. C after Richmond (1920)...... 201

Figure 11 emarginatus; third instar larva and egg case. (A) Habitus. (B) Head capsule, dorsal view. (C) Egg case, dorsal view. (D) Egg case, ventral view. Scale bars: A = 1 mm; B = 0.5 mm; C and D = 2 m m ...... 203

Figure 12 Spercheus emarginatus; third instar larva. (A) Left antenna, dorsal view. (B) Right mandible, ventral view. (C) Left mandible, dorsal view. (D) Labium, dorsal view. Scale bars: 0.2 m m ...... 205

Figure 13 Spercheus emarginatus; third instar larva. (A) Labro­ clypeus, dorsal view. (B) Abdominal segments 8 and 9, dorsal view. (C) Right maxilla, dorsal view. Scale bars: 0.2 m m ...... 207

Figure 14 Sperchopsis tessellata; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B = 0.5 mm; C = 0.2 mm. A after Spangler (1961) ...... 209

Figure 15 Sperchopsis tessellata; third instar larva. (A) Right mandible, dorsal view. (B) Labroclypeus, dorsal view. (C) Right antenna, dorsal view. (D) Right maxilla, dorsal view. (E) Labium, dorsal view. Scale bars: 0.2 mm ...... 211

xiii Figure 16 Sperchopsis tessellata; pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. Scale bars: 2 mm. All after Spangler (1961) ...... 213

Figure 17 Ametor scabrosus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B = 0.5 mm; C = 0.2 m m ...... 215

Figure 18 Ametor scabrosus; third instar larva. (A) Labroclypeus, dorsal view. (B) Right mandible, dorsal view. (C) Right antenna, dorsal view. (D) Left maxilla, dorsal view. (E) Labium, dorsal view. Scale bars: A, C-E = 0.1 mm; B = 0.2 m m ...... 217

Figure 19 Ametor scabrosus; pupa. (A) Ventral view. (B) Dorsal view. Scale bar: 2 mm. Both after Spangler (1962) ...... 219

Figure 20 Anticura flinti; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bar: A = 2 mm. All after Spangler (1979)...... 221

Figure 21 Anticura flinti; third instar larva. (A) Labroclypeus, dorsal view. (B) Left maxilla, dorsal view. (C) Right antenna, dorsal view. (D) Right mandible, dorsal view. (E) Labium, dorsal view. All after Spangler (1979) ...... 223

Figure 22 Anticura flinti; pupa. (A) Ventral view. (B) Dorsal view. Scale bar: 2 mm. Both after Spangler (1979) ...... 225

Figure 23 Berosus pugnax; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 7 and 8, dorsal view. Scale bars: A = 2 mm; B and C = 0.5 mm. All after Archangelsky (1994b)...... 227

Figure 24 Berosus pugnax; third instar larva. (A) Labroclypeus, dorsal view. (B) Left antenna, dorsal view. (C) Labium, dorsal view. (D) Right maxilla, dorsal view. (E) Left mandible, dorsal view. (F) Right mandible, dorsal view. Scale bars: A, B, D-F = 0.2 mm; C = 0.1 mm. All after Archangelsky (1994b)...... 229

xiv Figure 25 Berosus spp..; egg cases and pupa. (A) Egg case of B. pugnax. (B) Egg case of B. corrini. (C) Egg case of B. hoplites. (D) Pupa of B. pugnax, ventral view. (E) Pupa of B. pugnax, dorsal view. Scale bars: 2 mm. All after Archangelsky (1994b)...... 231

Figure 26 Berosus spp.; pupae. (A) Pupa of B. corrini, ventral view. (B) Pupa of B. corrini., ventral view. (C) Pupa of B. hoplites, ventral view. (D) Pupa of B. hoplites, dorsal view. Scale bars: 2 mm. All after Archangelsky (1994b)...... 233

Figure 27 Derallus angustus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Distribution of right stemmata. (D) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and D = 0.1 mm. All after Archangelsky & Durand (1992b) ...... 235

Figure 28 Derallus angustus; third instar larva. (A) First abdominal segment, dorsal view. (B) Right antenna, dorsal view. (C) Labroclypeus, dorsal view. (D) Right maxilla, dorsal view. (E) Right mandible, dorsal view. (F) Labium, dorsal view. Scale bars: 0.1 mm. All after Archangelsky & Durand (1992b) ...... 237

Figure 29 Derallus angustus; pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. Scale bars: 1 mm. All after Archangelsky & Durand (1992b) ...... 239

Figure 30 Chaetarthria sp; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 0.5 mm; B and C = 0.1 m m ...... 241

Figure 31 Chaetarthria sp.; third instar larva. (A) Left antenna, dorsal view. (B) Labroclypeus, dorsal view. (C) Labium, dorsal view. (D) Right maxilla, dorsal view. (E) Left mandible, dorsal view. Scale bars: A and C = 0.025 mm; B, D and E = 0.05 m m ...... 243

Figure 32 Guyanobius adocetus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Head capsule, ventral view. Scale bars: A = 1 mm; B and C = 0.5 mm. All after Spangler (1986) ...... 245

XV Figure 33 Guyanobius adocetus; third instar larva. (A) Left antenna, dorsal view. (B) Labroclypeus, dorsal view. (C) Right mandible, dorsal view. (D) Labium, dorsal view. (E) Right maxilla, dorsal view. All after Spangler (1986) ...... 247

Figure 34 subcupreus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and C = 0.2 m m ...... 249

Figure 35 Paracymus subcupreus; third instar larva. (A) Labro­ clypeus, dorsal view. (B) Left antenna, dorsal view. (C) Right mandible, dorsal view. (D) Labium, dorsal view. (E) Left maxilla, dorsal view. Scale bars: A, B, D and E = 0,05 mm; C = 0.1 m m ...... 251

Figure 36 Paracymus subcupreus; pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. Scale bars: 1 m m ...... 253

Figure 37 Crenitis sp; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and C = 0.2 m m ...... 255

Figure 38 Crenitis sp; third instar larva. (A) Right antenna, dorsal view. (B) Labroclypeus, dorsal view. (C) Right mandible, dorsal view. (D) Right maxilla, dorsal view. (E) Labium, dorsal view. Scale bars: 0.1 mm ...... 257

Figure 39 Crenitis punctatostriata; pupa. (A) Ventral view. (B) Dorsal view. (C) Distribution of styli on pronotum and head, dorsal view. (D) Styli. Scale bar: 1 mm. All after Matthey (1977) ...... 259

Figure 40 Anacaena infuscata; third and first instar larvae. (A) Habitus, third instar larva. (B) Right mandible, dorsal view. (C) Right antenna, dorsal view. Scale bar: 1 mm. All after Richmond (1920) ...... 261

Figure 41 Anacaena infuscata; first instar larva and egg case. (A) Labroclypeus, dorsal view. (B) Egg case. (C) Labium, dorsal view. (D) Right maxilla, dorsal view. All after Richmond (1920) ...... 263

xvi Figure 42 Notionotus liparus; first instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Labroclypeus, dorsal view. (D) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 0.2 mm; B = 0.1 mm; C and D = 0.05 m m ...... 265

Figure 43 Notionotus liparus; first instar larva. (A) Left mandible, dorsal view. (B) Left antenna, dorsal view. (C) Right mandible, dorsal view. (D) Left maxilla, dorsal view. (E) Labium, dorsal view. Scale bars: 0.05 mm ...... 267

Figure 44 Laccobius minutoides; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and C = 0.2 m m ...... 269

Figure 45 Laccobius minutoides; third instar larva. (A) Labroclypeus, dorsal view. (B) Right mandible, dorsal view. (C) Right maxilla, dorsal view. (D) Left antenna, dorsal view. (E) Left mandible, dorsal view. Scale bars: 0.1 mm ...... 271

Figure 46 Laccobius minutoides; third instar larva, pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. (D) Larva, labium. Scale bars: A-C = 1 mm; D = 0.025 m m ...... 273

Figure 47 Oocyclus sp; first instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 0.5mm; B = 0.2 mm; C = 0.1 m m ...... 275

Figure 48 Oocyclus sp; first instar larva. (A) Right maxilla, dorsal view. (B) Labium, dorsal view. (C) Left mandible, dorsal view. (D) Right mandible, dorsal view. Scale bars: 0.05 m m ...... 277

Figure 49 Oocyclus sp; first instar larva and egg case. (A) Labro­ clypeus, dorsal view. (B) Right antenna, dorsal view. (C) Egg case. Scale bars: A and B = 0.05 mm; C = 1 mm...... 279

xvii Figure 50 Helochares maculicollis; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B = 0.5 mm; C = 0.2 m m ...... 281

Figure 51 Helochares maculicollis', third instar larva. (A) Labro­ clypeus, dorsal view. (B) Left mandible, dorsal view. (C) Right mandible, dorsal view. (D) Right antenna, dorsal view. (E) Left maxilla, dorsal view. Scale bars: A-C and E = 0.2 mm; D = 0.1 m m ...... 283

Figure 52 Helochares maculicollis; third instar larva, pupa, and egg case. (A) Pupa, ventral * low. (B) Pupa, dorsal view. (C) Distribution of styli on pronotum, dorsal view. (D) Larva, labium, dorsal view. (E) Egg case, ventral view. Scale bars: A, B = 2 mm; D = 0.1 mm; E = 1 mm ...... 285

Figure 53 Helobata larvalis (= H. striata ); first instar larva and egg case. (A) Habitus. (B) Head capsule, dorsal view. (C) Egg case, dorsal view. (D) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 0.5 mm; C = 1 mm. All after Spangler (1972) ...... 287

Figure 54 Helobata larvalis (= H. striata ); first instar larva. (A) Labroclypeus, dorsal view. (B) Left maxilla, dorsal view. (C) Labium, dorsal view. (D) Left antenna, dorsal view. (E) Left mandible, dorsal view. All after Spangler (1972) 289

Figure 55 ochraceus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B and C = 0.2 m m ...... 291

Figure 56 Enochrus ochraceus; third instar larva. (A) Labroclypeus, dorsal view. (B) Right maxilla, dorsal view. (C) Right mandible, dorsal view. (D) Left antenna, dorsal view. (E) Left mandible, dorsal view. Scale bars: 0.1 mm ...... 293

Figure 57 Enochrus ochraceus; third instar larva, pupa, and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Larva, labium, dorsal view. (D) Egg case. Scale bars: A and B = 1 mm; C = 0.1 mm; D = 2 m m ...... 295

xviii Figure 58 Helocombus bifidus; first instar larva. (A) Habitus. (B) Labium, dorsal view. (C) Head capsule, dorsal view. . (D) Labroclypeus, dorsal view. Scale bar: 1 mm. All after Perkins & Spangler (1981) ...... 297

Figure 59 Cymbiodyta vindicata; third and second instar larvae. (A) Habitus, third instar. (B) Head capsule, dorsal view, second instar. (C) Labroclypeus, dorsal view, second instar (D) Abdominal segments 8 and 9, dorsal view, second instar. Scale bars: A = 2 mm; B and D = 0.2 mm, C = 0.1 mm ...... 299

Figure 60 Cymbiodyta vindicata; second instar larva. (A) Right maxilla, dorsal view. (B) Right antenna, dorsal view. (C) Labium, dorsal view. (D) Left mandible, dorsal view. (E) Right mandible, dorsal view. Scale bars: 0.1 mm ...... 301

Figure 61 Chasmogenus nitescens; third instar larva. (A) Habitus. (B) Mandibles and labroclypeus, dorsal view. (C) Left maxilla, dorsal view (D) Labium, dorsal view. Scale bars: A = 1 mm; B-D = 0.1 mm. All after Anderson (1976) ...... 303

Figure 62 Chasmogenus nitescens; pupa and egg case. (A) Pupa, ventral view. (B) Pupa, lateral view. (C) Egg case. Scale bars: 1 mm. All after Anderson (1976) ...... 305

Figure 63 melaenus', third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B and C = 0.5 m m ...... 307

Figure 64 Hydrobius melaenus; third instar larva. (A) Labroclypeus, dorsal view. (B) Left antenna, dorsal view. (C) Right mandible, dorsal view. (D) Right maxilla, dorsal view. (E) Detail of pubescence and asperities of abdominal segment 8. Scale bars: 0.2 mm ...... 309

Figure 65 Hydrobius melaenus; third instar larva, pupa, and egg case. (A) Larva, labium, dorsal view. (B) Egg case. (C) Pupa, ventral view. (D) Pupa, dorsal view. Scale bars: A = 0.2 mm; B-D = 2 m m ...... 311

xix Figure 66 Hydramara argentina; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bar: 5 mm. All after Spangler (1979)...... 313

Figure 67 Hydramara argentina; third instar larva. (A) Labroclypeus, dorsal view. (B) Right antenna, dorsal view. (C) Right mandible, dorsal view. (D) Left maxilla, dorsal view. (E) Labium, dorsal view. All after Spangler (1979) ...... 315

Figure 68 Tropisternus spp; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 3 mm; B = 1 mm; C = 0.5 m m ...... 317

Figure 69 Tropisternus sp.; third instar larva. (A) Labroclypeus, dorsal view. (B) Right maxilla, dorsal view. (C) Left mandible, dorsal view. (D) Right mandible, dorsal view. (E) Left antenna, dorsal view. (F) Labium, dorsal view. Scale bars: 0.5 m m ...... 319

Figure 70 Tropisternus sp.; third instar larva, pupa, and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. Scale bars: 2 mm. A and B after Fortich (1979) (T. setiger)...... 321

Figure 71 Hydrobiomorpha casta; third instar larva. (A) Habitus. (B) Left mandible, dorsal view. (C) Labium, dorsal view. Scale bars: A = 5 mm; B and C = 0.5 mm. All after Spangler (1973) 323

Figure 72 Hydrobiomorpha casta; third instar larva. (A) Abdominal segments 8 and 9, dorsal view. (B) Left maxilla, dorsal view. (C) Right antenna, dorsal view. Scale bars: 0.5 mm. All after Spangler (1973) ...... 325

Figure 73 Hydrochara caraboides and H. soror; third instar larvae. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B = 1 mm; C = 0.5 mm. B after Matta, 1982 (H. soror)...... 327

XX Figure 74 Hydrochara caraboides; third instar larva. (A) Labro­ clypeus, dorsal view. (B) Left mandible, dorsal view. (C) Right maxilla, dorsal view. (D) Left antenna, dorsal view. (E) Right mandible, dorsal view. Scale bars: 0.5 m m ...... 329

Figure 75 Hydrochara caraboides; third instar larva. (A) Labium, dorsal view. (B) Egg case. Scale bars: A = 0.5 mm; B = 5 mm. B after Richmond (1920) ...... 331

Figure 76 Dibolocelus ovatus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Detail of cuticular asperities. (D) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 10 mm; B = 2 mm; C = 0.5 mm. A-C after Archangelsky & Durand (1992a) ...... 333

Figure 77 Dibolocelus ovatus; third instar larva. (A) Labroclypeus, dorsal view. (B) Left mandible, dorsal view. (C) Right mandible, dorsal view. (D) Left maxilla, dorsal view. (E) Labium, dorsal view. (F) Left antenna, dorsal view. Scale bars: 1 mm. All after Archangelsky & Durand (1992a)...... 335

Figure 78 Dibolocelus ovatus; pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case, lateral view. (D) Egg case, anterior view. Scale bars: 10 mm. All after Archangelsky & Durand (1992a) ...... 337

Figure 79 triangularis; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 10 mm; B = 2.5 mm; C = 1 m m ...... 339

Figure 80 Hydrophilus triangularis; third instar larva. (A) Labro­ clypeus, dorsal view. (B) Left antenna, dorsal view. (C) Right mandible, dorsal view. (D) Left maxilla, dorsal view. (E) Left mandible, dorsal view. Scale bars: 1 mm ...... 341

Figure 81 Hydrophilus triangularis; third instar larva, pupa, and egg case. (A) Pupa, ventral view. (B) Larva, labium, dorsal view. (C) Egg case, lateral view. (D) Pupa, dorsal view. Scale bars: A, C and D = 10 mm; B = 1 mm. A after Wilson (1923a)...... 343

xxi Figure 82 Cylorygmus lineatopunctatus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Labro­ clypeus, dorsal view. (D) Abdominal segments 8 and 9, dorsal view. Scale bar: 1 mm. All after Spangler (1979)...... 345

Figure 83 Cylorygmus lineatopunctatus; third instar larva. (A) Left maxilla, dorsal view. (B) Right mandible, dorsal view. (C) Right antenna, dorsal view. (D) Detail of lateral and spiracular tubercles. (E) Labium, dorsal view. All after Spangler (1979) ...... 347

Figure 84 Cylorygmus lineatopunctatus; pupa. (A) Ventral view. (B) Dorsal view. Both after Spangler (1979) ...... 349

Figure 85 Phaenonotum exstriatum', third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and C = 0.2 mm. All after Archangelsky & Durand (1992c) ...... 351

Figure 86 Phaenonotum exstriatum; third instar larva. (A) Labro­ clypeus, dorsal view. (B) Right mandible, dorsal view. (C) Right antenna, dorsal view. (D) Right maxilla, dorsal view. (E) Labium, dorsal view. Scale bars: A = 0.05 mm; D-E = 0.1 mm. B after Archangelsky & Durand (1992c)...... 353

Figure 87 Phaenonotum exstriatum; pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. Scale bars: 1 mm. All after Archangelsky & Durand (1992c) ...... 355

Figure 88 Dactylosternum cacti', third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B = 0.5 mm; C = 0.4 mm. All after Archangelsky (1994a)...... 357

Figure 89 Dactylosternum cacti; third instar larva. (A) Right maxilla, dorsal view. (B) Labroclypeus, dorsal view. (C) Left antenna, dorsal view. (D) Hypopharyngeal lobe, dorsal view. (E) Labium, dorsal view. Scale bars: A-C = 0.2 mm; D and E = 0.1 mm. All after Archangelsky (1994a)...... 359

xxii Figure 90 Dactylosternum cacti; third instar larva, pupa, and egg case. (A) Larva, left mandible, dorsal view. (B) Larva, right mandible, dorsal view. (C) Egg case. (D) Pupa, ventral view. (E) Pupa, dorsal view. Scale bars: A and B = 0.2 mm; C-E = 2 mm. All after Archangelsky (1994a)...... 361

Figure 91 Dactylosternum sp; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B = 0.5 mm; C = 0.25 m m ...... 363

Figure 92 Dactylosternum sp; third instar larva. (A) Labroclypeus, dorsal view. (B) Right mandible, dorsal view. (C) Left antenna, dorsal view. (D) Right maxilla, dorsal view. (E) Left mandible, dorsal view. Scale bars: 0.1 mm ...... 365

Figure 93 Dactylosternum sp.; third instar larva and egg case. (A) Larva, labium and hypopharyngeal lobe, dorsal view. (B) Egg case. Scale bars: A = 0.1 mm; B = 1 mm ...... 367

Figure 94 Cercyon praetextatus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B = 0.2 mm; C = 0.5 m m ...... 369

Figure 95 Cercyon praetextatus; third instar larva. (A) Labro­ clypeus, dorsal view. (B) Right mandible, dorsal view. (C) Left antenna, dorsal view. (D) Left mandible, dorsal view. (E) Labium, ventral view. (F) Left maxilla, dorsal view. Scale bars: A, B, D, and F = 0.1 mm; C and E = 0.05 m m ...... 371

Figure 96 Cercyon praetextatus; third instar larva, pupa, and egg case. (A) Pupa, ventral view. (B) Larva, prothoracic leg. (C) Pupa, dorsal view. (D) Egg case. Scale bars: 1 mm ...... 373

Figure 97 Pelosoma sp; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and C = 0.2 mm ...... 375

xxiii Figure 98 Pelosoma sp; third instar larva. (A) Labroclypeus, dorsal view. (B) Left maxilla, dorsal view. (C) Right mandible, dorsal view. (D) Left antenna, dorsal view. (E) Left mandible, dorsal view. Scale bars: A= 0.1 mm; B-E = 0.05 m m ...... 377

Figure 99 Pelosoma sp; third instar larva, pupa, and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. (D) Labium and hypopharyngeal lobe, ventral view. Scale bars: A and B = 1 mm; C = 2 mm; D = 0.05 m m ...... 379

Figure 100 ; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and C = 0.2 m m ...... 381

Figure 101 Cryptopleurum minutum; third instar larva. (A) Left antenna, dorsal view. (B) Labroclypeus, dorsal view. (C) Right mandible, dorsal view. (D) Left maxilla, dorsal view. (E) Left mandible, dorsal view. Scale bars: 0.05 m m ...... 383

Figure 102 Cryptopleurum minutum; third instar larva, pupa, and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. (D) Labium and hypopharyngeal lobe, ventral view. Scale bars: A-C = 1 mm; D = 0.025 m m ...... 385

Figure 103 Pemelus costatus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B = 0.2 mm; C = 0.25 m m ...... 387

Figure 104 Pemelus costatus; third instar larva. (A) Labroclypeus, dorsal view. (B) Left mandible, dorsal view. (C) Left antenna, dorsal view. (D) Right maxilla, dorsal view. (E) Right mandible, dorsal view. Scale bars: A, C, and D = 0.05 mm; B and E = 0.1 m m ...... 389

Figure 105 Pemelus costatus; third instar larva, pupa, and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Labium and hypopharyngeal lobe, ventral view. (D) Egg case. Scale bars: A, B, and D = 1 mm; C = 0.05 m m ...... 391

xxiv Figure 106 obscurum; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Labroclypeus, dorsal view. (D) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and D = 0.2 mm; C = 0.05 mm. All after Quennedey (1965) ...... 393

Figure 107 Megasternum obscurum; third instar larva. (A) Labium and hypopharyngeal lobe, ventral view. (B) Left maxilla, ventral view. (C) Right antenna, dorsal view. (D) Left mandible, dorsal view. (E) Right mandible, dorsal view. Scale bars: A-C = 0.05 mm; D and E = 0.1 mm. All after Quennedey (1965) ...... 395

Figure 108 Sphaeridium scarabaeoides; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Detail of asperities on projections of abdominal segment 8. (D) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B and D = 0.5 m m ...... 397

Figure 109 Sphaeridium scarabaeoides; third instar larva. (A) Labium, dorsal view. (B) Labium and hypopharyngeal lobe, ventral view. (C) Right prothoracic leg. Scale bar: 0.1 mm. B after Quennedey (1965) ...... 399

Figure 110 Sphaeridium scarabaeoides; third instar larva. (A) Labroclypeus, dorsal view. (B) Right maxilla, dorsal view. (C) Right antenna. (D) Right mandible, dorsal view. (E) Left mandible, dorsal view. Scale bars: 0.1 m m ...... 401

Figure 111 Sphaeridium scarabaeoides; pupa. (A) Ventral view. (B) Dorsal view. Scale bar: 2 mm ...... 403

Figure 112 Cladograms obtained by Hansen (1991). (A) 534-step cladogram, obtained for 33 taxa and 176 characters (Cl = 0.34), only the hydrophiloid families are represented. (B) 535-step cladogram, obtained for 33 taxa and 176 characters (Cl = ? )...... 405

Figure 113 Representation of Hansen's cladograms as unrooted trees. (A) 534-step cladogram. (B) 535-step cladogram ...... 407

XXV Figure 114 Cladogram obtained by Beutel (1994). (A) Cladogram including Hydraenidae, obtained for 11 taxa and 39 characters (number of steps and Cl are not provided by he author. (B) Same cladogram represented as an un­ rooted tree ...... 409

Figure 115 Equally parsimonious cladograms obtained with characters from immature stages. Both cladograms obtained for 11 taxa and 44 characters (Cl = 0.68, excluding uninformative characters, RI = 0.737) ...... 411

Figure 116 Representation of cladograms obtained with characters from immature stages as unrooted trees ...... 413

Figure 117 Cladogram obtained by combining characters from adult and preimaginal stages. (A) 236-step cladogram, obtained for 9 taxa and 132 characters (Cl = 0.61, excluding uninformative characters, RI = 0.48). (B) Same represented as an unrooted tree (Hydraenidae has been excluded) ...... 415

xxvi CHAPTER 1

INTRODUCTION

State of knowledge of the immature Hydrophiloidea

The superfamily Hydrophiloidea contains around 145 genera and over 2,600 described species worldwide. It is included within the suborder and, following Hansen’s classification (1991), it is divided into six families: Helophoridae, Epimetopidae, Georissidae, Hydrochidae, Spercheidae, and Hydrophilidae. Although the adults are fairly well studied in Europe, North America, and parts of South America; the knowledge is still poor in other regions, especially in the tropics. As an example I can mention that over 20 genera (almost 15% of the known genera within the superfamily) have been described in the last 20 to 25 years, and there are still some awaiting description (Hansen 1990, 1991). In the New World, the Hydrophiloidea are represented by the six families mentioned above. There are 61 genera (Table 1) of which, prior to this study, only 32 had described larvae; the number of genera with described pupae was much lower, only 19. With the studies conducted for this dissertation, the number of genera with t described larvae and pupae has been increased to 39 (or 40 if the genus Dactylosternum is broken down) and 25 respectively (Table 2).

1 TABLE 1. New World Hydrophiloidea; classification down to generic level, modified from Hansen (1991).

Family Subfamily Tribe Genus

Helophoridae Helophorus Epimetopidae Epimetopus Georissidae Georissus Hydrochidae Hydrochus Spercheidae Spercheus Hydrophilidae Hydrophilinae Sperchopsini Sperchopsis Ametor Anticura Berosus Derallus Hemiosus Chaetarthriini Chaetarthria Guyanobius Anacaenini Paracymus Crenitis Anacaena Notionotus Oocyclini Laccobius Beralitra Oocyclus Acidocerina Troglochares Helochares Helobata Dieroxenus Enochrus Helocombus Cymbiodyta Chasmogenus Hydrophilini Hydrobiina Hydrobius Hydramara Hydrophilini Hydrophilina Tropistemus Hydrobiomorpha Hydrochara Dibolocelus Hydrophilus

2 TABLE 1 (Cont.). New World Hydrophiloidea; classification down to generic level, modified from Hansen (1991).

Family Subfamily Tribe Genus

Sphaeridiinae Rygmondini Cylorygmus Andotypini Andotypus Coelostomatini Cyclotypus Phaenonotum Dactylosternum Phaenostoma Lachnodactum Galapodactum Omicrini Omicrus Heteryon Aculomicrus Megastemini Cercyon Agna Tectostemum Deltostethus Pelosoma Oostemum Cryptopleurum Megasternum Motonerus Sacostemum Pemelus Nitidulodes Moraphilus Cyrcrillum Sphaeridiini Sphaeridium

3 In general immature stages of most insects are poorly known, and beetles are no exception. According to Newton (1990) the larvae of only 31% of the world genera of Hydrophiloidea (sensu Hansen) had been described at that time, and the larvae of only 6% of the species are known. Knowledge of pupal stage is even poorer. While most of the North American genera of hydrophiloids are known in their larval stages, with the exception of the subfamily Sphaeridiinae, the knowledge is still very incomplete for South and Central America. The inadequate knowledge of life cycles poses a major problem for many other areas of biological research that involve immature stages of beetles such as ecology, studies on species diversity, medical entomology or physiology.; the problems in many cases are due to the inability to identify larvae or pupae collected in the field. Most classifications and phylogenies are based on adults (Hansen 1991; Newton & Thayer 1992), mainly because of the small number of larvae that are known. With classical knowledge such as adult morphology, it is difficult to resolve some problems when reconstructing phylogenies. To overcome this, there are alternative approaches such as the study of immature stages. This option has been used successfully in other beetle taxa such as Elateridae and Hydradephaga, in which adults alone could not resolve relationships among subfamilies and genera (Johnson 1992, Beutel 1993, 1994). If we consider that the life cycle of a beetle has four stages: egg, larva, pupa and adult, then we can see that adults represent only one fourth of the life cycle of a beetle, and that by ignoring the immatures we are missing the rest of the information that could be used for classifications and phylogenetic reconstructions. Also, the role of the other stages in the ecosystem remains unclear; the main activity of adult hydrophiloids is usually reproduction, so their impact in the ecosystem is very small.

4 TABLE 2. New World Hydrophiloidea and state of knowledge of their immature stages (* immature stages described for the first time as part of this research).

Family Subfamily Genus Larva Pupa

Helophoridae Helophorus Known Known Epimetopidae Epimetopus Known Unknown Georissidae Georissus Known Unknown Hydrochidae Hydrochus Known Unknown Spercheidae Spercheus Known Known Hydrophilidae Hydrophilinae Sperchopsis Known Known Ametor Known Known Anticura Known Known Berosus Known Known Derallus Known Known* Hemiosus Unknown Unknown Chaetarthria Known Unknown Guayanobius Known Unknown Paracymus Known Known Crenitis Known Known Anacaena Known Unknown Notionotus Known* Unknown Laccobius Known Known Beralitra Unknown Unknown Oocyclus Known* Unknown Troglochares Unknown Unknown Helochares Known Known Helobata Known Unknown Dieroxenus Unknown Unknown Enochrus Known Known Helocombus Known Unknown Cymbiodyta Known Unknown Chasmogenus Known Known Hydrobius Known Known Hydramara Known Unknown Tropistemus Known Known Hydrobiomorpha Known Unknown Hydrochara Known Known Dibolocelus Known* Known* Hydrophilus Known Known

5 TABLE 2 (Cont.). New World Hydrophiloidea and state of knowledge of their immature stages (* immature stages described for the first time as part of this research).

Family Subfamily Genus Larva Pupa

Sphaeridiinae Cylorygmus Known Known Andotypus Unknown Unknown Cyclotypus Unknown Unknown Phaenonotum Known* Known* Dactylosternum Known* Known* Phaenostoma Unknown Unknown Lachnodactum Unknown Unknown Galapodactum Unknown Unknown Omicrus Unknown Unknown Heteryon Unknown Unknown Aculomicrus Unknown Unknown Cercyon Known Known Agna Unknown Unknown Tectostemum Unknown Unknown Deltostethus Unknown Unknown Pelosoma Known* Known* Oostemum Unknown Unknown Cryptopleurum Known* Known* Megastemum Known Unknown Motonerus Unknown Unknown Sacostemum Unknown Unknown Pemelus Known* Known* Nitidulodes Unknown Unknown Moraphilus Unknown Unknown Cyrcrillum Unknown Unknown Sphaeridium Known Known

6 One of the reasons that hydrophiloids are a very interesting and diverse group of beetles is that its members are adapted to both aquatic and terrestrial habitats. About half of its members are considered aquatic or semiaquatic (hygrophilous), living in different aquatic habitats, near water or in extremely moist situations. The aquatic members are found in a variety of situations such as lotic and lentic environments, or even in phytotelmata (small bodies of water formed by plants, such as bromeliads, Heliconia flowers, or treeholes that gather rain water). Some of the species found in aquatic habitats are very good swimmers ( Hydrophilus, Tropisternus, Berosus, Laccobius, etc.). Others do not swim at all, but still retain morphological and behavioral adaptations for breathing and eating, and they also can float in the event that they are removed from the substrate on which they are found. The other part of the family, which is most of the Sphaeridiinae, is terrestrial and can be found in a variety of habitats such as dung, decomposing plant matter, treeholes, or rotting fungi, but all of these habitats are usually fairly moist. The Sphaeridiinae have many species that are associated with dung, and as may be expected, several of the species associated with cattle and other domestic are not native to the New World, but have been introduced from the Old World. One character that both aquatic and terrestrial hydrophilids have in common is that their larvae are always predaceous (the feeding habits of Hydrochus are still unresolved), and the adults are mainly scavengers, only some species have been reported to have adults that are also predators.

There have not been many attempts to summarize the knowledge of the hydrophiloid beetles from the point of view of their immature stages. One of the most complete papers is that of B0ving & Henriksen (1938), which covers the Danish hydrophiloids as well as hydraenids, which are now included within the staphylinoids.

7 Bertrand (1972) summarizes the knowledge at the generic level in a worldwide spectrum, but his treatment of each genus is brief. For the North American fauna there are two important papers that cover immature stages and biology of some these beetles: Richmond (1920), and Wilson (1923b), but as that of Bpving & Henriksen (1938), they are outdated and several new genera and species have been described since then. For the Neotropical region, there are no papers summing up information on the preimaginal stages and biology of hydrophiloids. Leech & Chandler (1956), Pennak (1978), Brigham & Brigham (1982), and Merrit & Cummins (1984, 1996) published keys to the larvae and adults of aquatic and semiaquatic genera of North American hydrophiloids.

Objectives

This dissertation is a taxonomic and bionomical study of the immature stages of the hydrophiloids, and makes important contributions in several areas: knowledge of the larval and pupal stages; their role in the ecosystem; identification of immatures for ecological studies; rearing techniques; the potential use of immatures in biological control of pest species and bioindicators; and fundamental phylogenies and classifications based on characters of both adults and immatures.

Systematic Position of the Hydrophiloidea

Hydrophiloids are within the suborder Polyphaga. There is general consensus that the Hydrophiloidea are included within the beetle series Staphyliniformia

8 (Lawrence and Newton 1982; Hansen 1991, 1995; Newton and Thayer 1992, Beutel 1994), but there is disagreement regarding which families should be included within the Hydrophiloidea. Some authors, in a wider sense, include the family Histeridae within the hydrophiloids (Lawrence and Newton 1982; Newton and Thayer 1992). Other authors (Crowson 1955, 1967; Hansen 1991) do not include the histerids within the hydrophiloids. The scope of this dissertation is not to resolve the problems of higher classification within the series Staphyliniformia, and the classification followed here, for taxa of tribal or higher levels, is that of Hansen (1991).

Polyphaga is the most diverse group of Coleoptera, containing over 90% of the beetle species (Lawrence & Newton 1982; Lawrence & Britton 1992). Characters defining the adult Polyphaga are several: 1- propleuron fused with the trochantin and concealed (there is no external propleuron, and therefore no notopleural sutures); 2- hindwing without an oblong cell and with transverse fold never crossing MP; 3- cervical sclerites present; 4- ovarioles of the telotrophic type; 5- hind coxae motile and not dividing the first abdominal stemite. Larval characters are more variable, but the following can be mentioned: 1- legs 5-segmented (opposed to 6-segmented as in Archeostemataand ), a character shared with ; 2- typically 3-segmented antennae; 3- short epicranial suture; 4- typically six stemmata on each side of the head; 5- typically mandibles with mola, prostheca, and ventral process; 6- galea separated but not articulated; 7- typically with annular-biforous spiracles which have a closing apparatus; 8- typically with abdominal segment 10 well developed and terminal. Many of these characters are modified in at least some of the hydrophiloids, some of these modifications are correlated with their aquatic and predatory habits, these modified characters include mandibles without prostheca, and in most cases with reduced mola; most spiracles non-functional, and

9 those functional contained within a respiratory atrium, which provides a secondary closing apparatus.

More narrowly, Staphyliniformia members are separated from the other Polyphaga by the presence of segmented urogomphi in the larvae (with a few exceptions), and a folding wing mechanism that has no spring present, and abdominal movements help to fold the wings (Lawrence & Newton 1982). As I mentioned above, the Staphyliniformia can be divided into two (Hydrophiloidea + Staphylinoidea) or three (Hydrophiloidea + Histeroidea + Staphylinoidea) superfamilies.

There are basically three different interpretations of the families that are included within the Hydrophiloidea. The first one is that of Lawrence and Newton (1982) and Newton and Thayer (1992), in which Histeridae and Hydrophilidae (including Helophoridae, Epimetopidae, Georissidae, Hydrochidae, and Spercheidae as subfamilies) are the only two families within the Hydrophiloidea. The second interpretation, and the one followed here, is that of Hansen (1991, 1995), in which Hydrophiloidea is treated in a narrower sense, placing Histeridae (together with Sphaerididae and Synteliidae) in its own superfamily. Finally, a third interpretation has Hydraenidae (considered within the Staphylinoidea by the above authors) as forming part of the Hydrophiloidea. This point of view is defended by Crowson (1967, 1981) and more recently by Beutel (1994). The first two points of view are not conflicting, and merely a matter of inclusiveness. On the other hand, the third point of view is conflicting with the first two, and is supported by several characters that may represent convergent adaptations to an aquatic environment. This will be discussed in more detail in Chapter 6, during the analysis of the phylogenetic relationships of these beetles.

1 0 CHAPTER 2

MATERIALS AND METHODS

Collecting Techniques

The material studied in this dissertation came from: Argentina, Venezuela, Guatemala, different parts of the USA, and in a few cases from Europe ( Spercheus emarginatus, Hydrochara caraboides, and ). Due to the variety of habitats in which hydrophiloid beetles are found, different techniques were necessary to find and collect specimens of as many genera as possible. Aquatic species were collected using aquatic nets or also by carefully inspecting logs, rocks, and leaf litter laying in the water or close to the margins; a few genera were also found on floating vegetation ( Derallus, Phaenonotum, and Hydrochus), so in these cases the plants were placed on white pans with water and inspected carefully. Semiaquatic species were successfully collected from plant debris or algae accumulated on the margins of creeks, ponds, or other bodies of water; the material was placed in white pans, from which the specimens were picked; adults were easily seen because their plastrons make them float. Another method to find these beetles (including larvae) is by the use of an ordinary Berlese funnel; the plant debris was placed on a wire mesh, and the insects fell in ajar containing wet paper towel which keept them alive.

11 Terrestrial specimens were more difficult to locate; they can be found in many different habitats such as treeholes, decomposing plant material, under bark, in dung, and also in phytotelmata. Samples were usually collected in bags and carried back to the laboratory where they were processed using Berlese funnels. Hydrophiloids living under bark were collected by peeling trees that have bark in an advanced state of decomposition. Another good source for these beetles was rotting cacti or fruits such as cacao. Hydrophilids living in phytotelmata were less common, but some of the most interesting; these were collected from bromeliads or flowers such as those of Heliconia plants in the tropics; the adults go there to lay eggs in the axis of leaves or at the base of flowers; the larvae, after hatching, feed on dipteran larvae, which are common in these habitats. Another good collecting technique for terrestrial species was the use of pitfall traps with different baits. To keep the beetles alive, the containers had a fine mesh at the bottom (to avoid flooding in case it rains), and some plant debris so that the small hydrophilids could hide from other predatory that could fall in these traps; the top of the container also had an inverted funnel to prevent the insects from escaping. The screen or hardware cloth used on top of the trap can be of different sizes (usually half to a quarter inch in diameter); this helped to exclude larger arthropods from falling in the trap (large spiders, opilionids, dung beetles, etc.) and also prevented small mammals from digging out the traps, and eating the insects in it. Light traps attracted all kinds of insects, including both aquatic and terrestrial hydrophiloids; the only drawback was that one does not know the habitat where the beetles were coming from. Finally, the specimens collected had to be kept alive. To do this, the adults of each species were kept in plastic containers with a tight lid, and a fine mesh on the cover that allowed gas exchange. Inside the container was usually a wet paper towel or moss, to keep a high level of humidity and also to provide a substrate for the beetles. This set up worked well for both aquatic and terrestrial species, but only for a few days.

1 2 During longer trips, the specimens were kept in larger plastic containers, with some of the natural substrate collected at the same site where the beetles were found. It also helped to keep them in a cooler with some ice during warm days (5 to 10°C is a good temperature), because the temperature in these small and closed containers increased very rapidly during hot summer days, and this could kill the specimens.

Rearing Techniques

The methods for rearing hydrophilids in the laboratory were quite varied and fell into several categories. Adults had different requirements than larvae or pupae, and also each genus had it own requirements, but within the genera, the methods were constant. To simplify descriptions, adult habitats were subdivided into three categories, and larval habitats into two (in this section the word habitat refers to an artificial or “laboratory habitat”). Adults of aquatic species were kept in aquaria of different sizes, according to the size of the species. In the case of large hydrophilids such as Dibolocelus and Hydrophilus, aquaria of 30 or 60 liters were needed (these species reach lengths of up to 50 or 60 mm). Smaller genera such as Tropistemus or Berosus were kept in smaller containers, usually 1 to 3 liters. Regardless of the size of the aquarium, there had to be plenty of vegetation, which the adults used for support, food, and oviposition; some aeration was also necessary to keep the water circulating and clean. Food for the aquatic species depends on the genera; some fed mainly on algae or detritus from the bottom, others prefered plant material, and some others would feed on almost anything. A good food source was fish food in flakes. It was readily consumed by most of the species reared during these studies, and is well balanced regarding the protein, fat, and fiber

13 contents. Young (1958) suggested the use of dog food, but it has to be broken into small pieces, and also fouls the water very quickly. Genera reared using this kind of set up were: Hydrophilus, Dibolocelus, Tropistemus, Berosus, and Derallus. Hygrophilous or semiaquatic genera had quite different requirements. They required a habitat that offered both water and a dry substrate. To do this, plastic containers (such as Tupperware) were transformed into a “littoral habitat” by placing soil or sand on one half of the container, and water on the other half; the container was slightly inclined to prevent the soil from absorbing all the water and becoming too wet. Once the container was ready, leaf litter and pieces of wood and algae were placed inside; the leaf litter and wood served as hiding places for the adults, and the algae in the water kept it clean and also served as food for the beetles; the water level was kept constant by adding water every once in a while. As with aquatic species, fish food was provided regularly as the main source of food. To keep the container properly aerated, a piece of the lid was cut off and replaced with a fine mesh, which allowed air to circulate, but prevented the beetles from escaping. Egg laying among these genera usually varies, some constructing their egg cases on or under the leaf debris, and others laying their eggs in the substrate (either sand or soil). Genera reared using this kind of set up were: Helophorus, Hydrochus, Paracymus, Laccobius, Helochares, Enochrus, Cymbiodyta, Hydrobius, Phaenonotum. The terrestrial species did not require water in the containers where they were being kept, but high levels of humidity were necessary to prevent dehydration. For these genera, the important point for success was to rear them in the same kind of substrate where they were found. This varied with each species, so some needed to be kept in dung, some in soil, or on substrates of different kind. The best way to do this was by collecting some of the substrate on which the adults were collected in the field. For example, I have reared different species of the genus Dactylosternum that were

14 collected on different substrates: rotting cactus, rotting bark, and decaying tissue of Araceae plants; these substrates were brought back to the laboratory with the adults, and egg laying in all three cases was successful. Again, fish food was used to feed the adults, but also fly eggs and small maggots were added in order to make the habitat look more “natural” and stimulate the adults to lay eggs (hydrophilid larvae of these genera feed mainly on fly eggs and maggots). Genera reared using this kind of set up were: Dactylosternum, Cercyon, Cryptopleurum, and Sphaeridium. Finally, some genera did not fall in any of the previous categories and had to be reared under special conditions. Three examples are Oocyclus, Notionotus, and Pelosoma. The adults of the first two genera were collected in hygropetric habitats, living in the moss and leaf debris collected on steep walls on the sides of small montane creeks in Venezuela. To recreate the habitat as closely as possible, pieces of rock and moss from the collection sites were carried to the lab and placed in plastic containers, with some water to keep the container humid. In the case of Pelosoma, they were collected in phytotelmata, more precisely in Heliconia flowers. The adults live in these flowers, which collect rain-water and serve as breeding sites for several species of Diptera (such as Culicidae); they lay eggs at the base of these flowers, and when the larvae hatch, they crawl into the flowers looking for prey. In the case of Pelosoma, flowers had to be collected and kept in plastic containers; the water level was kept constant within the flowers, to prevent them from getting dry. Some other hydrophilid species have been reported to live in phytotelmata (d’Orchymont 1937, Frank 1983).

Once egg cases are laid, the second part of the rearing process starts. The egg cases had to be collected and transferred to smaller containers. For aquatic genera, the egg cases were placed in small cups or tissue culture cells (plates with six or 12 cells were used, with the size of the cells ranging between one to one and a half inches) with

15 water and some fine sticks or blades of grass to provide support for the larvae when they hatch. Egg cases of larger genera such as Hydrophilus (which have over 100 eggs) were placed in shallow pans with 2 to 3 cm of water and plenty of Elodea plants. Terrestrial and hygrophilous species were treated in a different way, but both were similar in their requirements. For all of them, the egg cases were collected and placed in tissue culture cells with damp filter paper.

After the eggs hatch, the larvae had to be transferred to clean cells. Tissue culture cells were the easiest to use, except for larger species for which small cups had to be used. To prevent cannibalism, only one larva was placed in each cell or cup. Aquatic species were kept throughout their larval cycle in containers with water and sticks or grass as support. The water had to be changed every other day to keep it clean, and food was usually supplied twice a day. Food for aquatic larvae can be: Artemia salina for very small first instar larvae (e.g. Derallus), Chironomidae larvae, maggots (from Sarcophaga spp. or Musca domestica), and Tubifex. Live prey were preferred to dead ones because they do not foul the water; in the case of maggots, they had to be removed after they drown or they would start to decompose. In one case, Dibolocelus, the only food they would take were aquatic snails (of the genera: Physa, Goniobasis, and Gyraulus). Semiaquatic (e.g. Helophorus, Enochrus, etc.) and terrestrial larvae (e.g. Cercyon, Dactylosternum, etc.) were easily reared in containers with damp filter paper as the substrate. Four or five layers of paper were placed in the bottom of the cell where the larvae were kept, water drops were added until the paper became saturated, and finally the larvae and their food could be placed inside. They were transferred to a clean cell every two or three days, or when the paper became dirty and before mold started to develop in the container or on the food.

16 All larvae (aquatic, semiaquatic, or terrestrial) were fed at least once a day, in the case of large larvae such as those of Hydrophilus and Dibolocelus even twice a day. The prey offered were larger as the larvae grew and develop through the different instars. It was important to keep the containers tightly closed throughout the developmental cycle; larvae (especially the small first instars) can escape easily through very narrow cracks or apertures between the lid and the containers, and they desiccate very quickly.

At some point during the third instar, larvae stop feeding, and became more active. Their body contents also became whitish and the internal organs were difficult to recognize through the cuticle (this was probably the result of an increase in the concentration uric acid). This was the prepupal stage and attention had to be paid at this point in the development of the larvae. When they reached this stage, they had to be transferred to new containers for pupation. In some species they were transferred to containers with damp soil or sand; prepupae usually wandered for a couple of days and then buried themselves, and constructed a pupal cell where they finally pupated. In some other species, they built the pupal cell with the filter paper (Archangelsky 1994); larvae chew the filter paper and constructed a paper wall that surrounds them. In only one case, Derallus (Archangelsky & Durand 1992), the prepupae moulted into pupae completely exposed. The length of the prepupal stage varied among different species. It usually lasted two to five days, but sometimes it took 10 or more days. I have not been able to establish if these differences were natural among different species, or if they had something to do with the rearing conditions. In some cases I have not been able to obtain pupae, because the prepupae kept wandering and died before pupation.

17 Pupation did not take place immediately after the prepupa had built the pupal cell. It took a couple of days, and sometimes even one or two weeks. It was important to keep the level of humidity of the soil constant and avoid dehydration of the prepupae, or pupae, because they were very susceptible at this point. To keep track of the time spent until pupation, it is a good idea to dig through the soil or sand of the container until the pupal cell is reached, then it can be covered with a few pieces of filter paper. In this way the paper can be lifted at any time to check on the prepupa or the pupa, without having to dig every time and distress the beetles. It also helps to maintain the humidity level more accurately, because if the filter paper on the top starts drying, this means that the soil underneath is also becoming too dry. With prepupae that constructed the cell by chewing paper, I made a small hole on the side of the cell, large enough to see the specimen, and it was covered with another piece of clean filter paper.

The two most critical periods while rearing these beetles were the first larval instars, and the prepupal stage. In the case of the first instar larvae, the difficulty was to find the proper food. Many of these species were very small, and it was difficult to obtain prey small enough to feed them. This is the reason for which several of the genera I have tried to rear never went past the first larval instar (Notionotus, Hydrochus). With the prepupal stage, the problem was to find the appropriate substrate for them to build the pupal chamber, and pupate. This problem in some cases could be solved by collecting the substrate where the adults were collected, but even this may fail (i.e. Pelosoma).

More detailed descriptions of the techniques used to rear hydrophilids can be obtained from Angus (1973), Hosseinie (1976a-c), Archangelsky & Durand (1992a-c), and Archangelsky 1994a-b).

18 Study of Larval and Pupal Morphology

Larvae and pupae were fixed with boiling water. First, water in a beaker was brought to a boil, the beaker was removed from the hot plate, and then the specimens were placed in the hot water. According to their size, the larvae or pupae were left in the water somewhere between 30 and 60 seconds. After this the specimens were transferred to vials with 75% alcohol, and after two or three days they were transferred again to new vials with 75% alcohol and 3% glycerine. The glycerine prevents drying of the specimens in case the alcohol evaporates. Larvae were usually fixed 12 to 24 hours after they emerged or moulted; this allowed enough time for the cuticle to harden. Pupae were usually fixed when the eyes of the pharate adult turn red. One easy procedure that helps the pupae to retain their shape is to puncture them in a couple of places (usually underneath the wing-pads, on each side) right after fixation; this was done with a minuten, or a # 000 entomological pin. If this is not done, pupae tend to swell and their wing-pads and appendages become extended. The fixing procedure was also easily performed in the field, but only with small or medium size larvae (up to 15 or 20 mm). To do this I used glass test tubes with a little water, enough to cover the larvae. Then I boiled the specimens using a small flame such as that from a cigarette lighter. I usually carried two or three test tubes of different sizes tucked one inside the other, and this allowed me to fix almost any larva in only a couple of minutes.

19 Once the specimens were fixed, they had to be prepared for morphological studies. Pupae were studied without having to clear or dissect them, they are fairly large, and only the external morphology was studied. Larvae on the other hand had to be dissected and cleared in order to see the mouthparts and fine details of their morphology, such as structure of the spiracular atrium or chaetotaxia. The easiest way to clear the specimens was by the use of lactic acid. Lactic acid is a very gentle clearing agent, and can be used cold or on a warming tray, depending on the size of the larvae and on how fast we want to clear the larvae. It was used pure, and the larvae were placed in the clearing container with some alcohol; the alcohol slowly evaporated, and the interiors of the specimens were replaced with lactic acid, and gently cleared. This process may take from two days to more than week with very large larvae. In the case of larvae with a dark cuticle ( Dibolocelus, Spercheus), the lactic acid dissolved the internal contents, but after this they were treated with hydroxy peroxide for a few hours, up to a day. The peroxide turned the cuticle to a much lighter color; in this way the larvae could be studied with a compound microscope. Cleared larvae are mounted on slides for observation and description. The medium used for this purpose is Hoyer’s. Larvae can be mounted whole, but this usually makes it very difficult to study the mouthparts, appendages, and chaetotaxia of the sides and underside of the specimens. Usually the head and mouthparts and legs were dissected and mounted on separate slides; in this way they were easily seen, and drawings could be made with the aid of a camera lucida. Parts of the thorax and abdomen were also mounted in this way. Species for which only one or two larvae were obtained were studied in fresh Hoyer’s medium, and then returned to alcohol vials; this allowed the manipulation of the larva into different positions for study and to make drawings.

2 0 After mounting the different parts of the larvae, the slides had to be placed on a warming tray for a day or two, and then within a drying oven for three or four weeks (depending on the room humidity). This gave plenty of time for the Hoyer’s to dry and avoided accidents in which the cover slips move to the sides, especially when immersion oil was used. The drawings were done using a dissecting scope Wild M5 with a camera lucida, and a compound scope Wild M20 also with a camera lucida.

2 1 CHAPTER 3

GENERAL MORPHOLOGY OF THE HYDROPHILOIDEA

The following description is an account of the general morphological features of the hydrophiloid egg cases, larvae and pupae. There is substantial variation among different families and also among genera; more detailed descriptions are provided in the taxonomic section. In order to be consistent with the morphological nomenclature used for larvae, I am following, with a few modifications, Stehr (1989,1991), especially the chapter on Coleoptera coordinated by J. E Lawrence.

Egg cases Most hydrophiloids lay their eggs within silk cases. Usually these egg cases are fairly elaborate, having a characteristic form for each genus, and sometimes also for each species (Figures 3C, 16C, 19C, 49C). Only a few Sphaeridiinae lay their eggs in loose silk-webs (just a single layer of silk surrounding or covering the eggs). Most species build two-layered egg cases, the first one applied over the substrate on which the eggs are laid, and the second layer covering the eggs. The silk is produced by the accessory glands of the females (colleterial glands), and is worked by a pair of spinnerets (modified female genitalia). Eggs can be laid singly or in groups of two or more, up to over a hundred in one case ( Hydrophilus). The number of eggs in each case can be more or less constant for some species ( Berosus, Phaenonotum, Derallus,

2 2 etc.) or it may vary in others ( Tropistemus, Dibolocelus, etc.). Up to now there are four known genera in which the females carry the egg case under their abdomen: Epimetopus, Spercheus, Helochares, and Helobata (Figures 11C and D, 52E). In most cases the egg cases are attached to the substrate (aquatic plants, dung, decaying plant material, etc.), except for some of the large species such as in Hydrophilus, Dibolocelus and Hydrochara in which the egg cases float freely (Figure 78C and D). Many of the aquatic and hygrophilous genera have a mast or ribbon-like structure which sticks up, out of the water surface; the purpose of this mast is still a subject of discussion and could have more than one function, but its presence is variable even within the same genus.

Larvae Body form: Campodeiform except for those genera with reduced legs. Variously shaped but usually elongated and semi-cylindrical (somewhat flattened in cross section). Cuticle soft and in most cases lightly colored, except for the sclerotized regions (head, and parts of the thorax and abdomen). Tubercles, asperities, pubescence, gills and protuberances present in some taxa.

Head capsule: Always strongly sclerotized, prognathous; somewhat flattened dorso- ventrally. Epicranial sulcus (ecdysal line) well developed in first and second instars, sometimes difficult to see in third instar larvae (i.e. Berosus and many Sphaeridiinae). Epicranial sulci variously shaped, basically composed of three elements: two frontal arms or sulci, and a coronal sulcus or epicranial stem. Frontal sulci, extend from base of the antennae to back of the head, fusing before reaching occipital foramen, adopting basically four different shapes (Figures 14B, 50B, 79B, 82B): Y-, U-, liriform, and inverted bell-shape. Coronal sulcus typically very short, in many cases lost. Epicranial

23 sulcus subdivides the head into three plates: the frons in front and/or between the two frontal sulci, and two epicranial plates to the sides of the frontal sulci. These epicranial plates may or may not meet underneath the head; separated by the labium and the gula in Spercheidae and Hydrochidae; but meeting along the gular suture in remaining families of Hydrophiloidea. Clypeus and labrum fused, forming what is called labroclypeus, formed by the nasale, or median projection, and lateral lobes of the epistome; labroclypeus can be symmetrical (Figure 2B) or asymmetrical (Figures 18A and 24A). Nasale usually as a more or less developed projection that can carry one or more teeth, in a few cases is poorly developed and flat (Figures 77A and 80A); lateral lobes of the epistome extend forward from base of antennae, covering base of mandibles, usually rounded or more or less pointed in some cases (Figures 18A and 59C); relative size of nasale and lateral lobes of epistome are important for generic and sometimes specific identification. Stemmata number 6 or less, in some species fused together in one or two ocular areas, and difficult to tell apart (especially in third instar larvae, i.e. Phaenonotum, Sphaeridium). Occipital foramen wide, connecting with thorax; in most genera a pair of small cervical sclerites is present along dorsal margin of foramen, providing flexibility to bend the head upwards in order to facilitate food ingestion (Figures 17A and B, 14A and B).

Antennae: Inserted on antero-lateral margins of the head, arising from antennal fossae (cavities). Usually three-segmented (Figure 2A), basal segment (scape), middle (pedicel), and distal (flagellum), but in some cases four segmented (Figures 77F and 80E) ( Hydrophilus, Dibolocelus). Segment length varies among genera, but in aquatic taxa basal segment length usually longer than in terrestrial or semiaquatic hydrophiloids. Penultimate segment with sensory appendage (sensorium), sometimes as long as last antennal segment, but may be reduced and difficult to see (subtribe

24 Hydrophilina, Spercheus). Helophorus and Georissus with two sensoria. The function of this sensorium seems to be chemosensory (Zacharuk 1971), and probably olfactory (Schneider & Steinbretch 1968; Corbiere 1969). Studies by Scott & Zacharuk (1971) on elaterid larvae describe it as a compound sensillum basiconicum formed by the union of about 12 individual sensilla.

Mandibles: Well developed and strongly sclerotized, always pointing forward (prognathous), and sickle shaped. Mandible movement horizontal; acetabulum dorsal, condyle ventral. Mandible shape symmetrical (Figure 2D) to strongly asymmetrical (Figures 24E and F, 90A and B). Inner teeth vary from one to three, absent in only a few cases (some Sphaeridiinae). Inner margin partly serrated in some genera. Prostheca absent. Hydrochus with small molar area at base of mandibles (Figure 10E); larvae of Helophorus and Georissus with penicillus formed by several setae (Figures 2D and IE).

Maxillae: Large and conspicuous (usually larger than antennae), five-segmented (Figure 2E), with a very small cardo appearing as a small basal sclerite, subdivided in many cases, sometimes difficult to see. My interpretation of the maxilla differs from that of Lawrence (1991). Basal segment (stipes), very large, flattened dorso-ventrally, in many cases as long or longer than the rest of the maxillar segments combined (Figure 74C); next segment (palpifer), carries maxillary palp and an apical inner process (galea); palps three-segmented. Lawrence (1991) considers the palpifer as the first palpal segment, according to this interpretation hydrophiloid larvae would have four-segmented palpi, the first of them carrying the galea; since the galea is derived from the stipes (the palpifer is a subdivision of the stipes), it seems logical to consider hydrophiloids as having three-

25 segmented palpi. The stipes of Spercheus (Figure 13C) has a well developed lacinia, and a smaller one can be seen in Hydrochus (Figure 10B), the lacinia is missing in the rest of the known hydrophiloids.

Labium: Submentum (basal), mentum (median) and a prementum (distal). Submentum large, attached to head capsule, usually subtriangularor subpentagonal in shape (Figures 32C and 107A). Mentum well developed and usually quadrangular in shape, with free movement; dorsal surface can be smooth or covered by spines or hairs (Figures 15E and 109A). Prementum with a pair of two-segmented palpi and median appendage (ligula), that can be reduced or missing in several families and genera, i.e. Helophoridae, Hydrochidae, and several Hydrophilidae such as Berosus (Figure 24C), some Dactylosternum spp., etc. Dorsal or ental surface of the labium (mentum) forming hypopharynx. Hypopharynx smooth, or covered by a dense pubescence of cuticular spines. A few Sphaeridiinae genera have an asymmetrical hypopharingeal lobe, developed on left side (in dorsal view), which appears as a hairy subtriangular tongue (Figures 93A and 99D).

Thorax and Legs: Thorax three-segmented. Prothoracic tergum usually well developed, with a median sagittal or ecdysal line. Meso- and metathoracic terga smaller, usually oval or subtriangular in shape. Prosternite usually subrectangular or subtrapezoidal, in front of forelegs, with an acute projection articulating with coxa. Spiracles on mesothorax one pair, non-functional except for Helophorus, Georissus, and Epimetopus. Some genera with projections or lobes protruding from meso- and metathorax (Derallus, Crenitis). Legs typically 5-segmented, but in Georissus, Chaetarthria, Cercyort, Pelosoma, Cryptopleurum, and other Sphaeridiinae reduced or even absent (Figures 8 A

26 and 96B). There are two interpretations regarding the organization of the leg segments. The basal three are the coxa, trochanter, and femur; the disagreement involves the last two segments. These two segments are the tibiotarsus (tibia fused with the tarsus) and the claw or pretarsus (Boving & Henriksen 1938, Van Emden 1942). Alternatively they are the tibia and the tarsungulus (tarsus fused with the claw) (Crowson 1955, Lawrence 1991). There is evidence supporting both hypotheses (Crowson 1981).

Abdomen: Less sclerotized than thorax, ten-segmented, usually with first seven or eight segments similar in size and shape, with only a few small dorsal plates; segments nine and ten variously reduced or modified. First seven or eight segments commonly with two or three transverse folds or plicae. Urogomphi usually short and one- segmented; Helophorus with larger, three-segmented urogomphi (Figure 1C). Almost all known genera with spiracular atrium formed by the segments eight and nine well developed (Figures 14C and 17C), lacking in Helophorus, Georissus, Epimetopus, and Berosus. Ventral “prolegs” (without crochets of the Lepidoptera larvae) and rows of setae characteristic of some genera (Enochrus, Dactylostemum). Spiracles present in segments one to eight, usually those of first seven segments non-functional, those of segment eight enlarged and protected within spiracular atrium. Several genera such as Derallus or Hydrochara, with projections or lobes projecting from the abdominal segments (Figures 27A and 73 A). Tracheal gills known only in Berosus (Figure 23A), number and distribution variable among different species (Bertrand 1972, Archangelsky 1994).

Pupa Exarate and adectic (Hinton 1946), modified from Linnaeus (1758); appendages (antennae, mouthparts, wings and legs) free, mandibles non-functional. Color usually

27 white (sometimes light green, i.e. Derallus), with red or brownish eyes in mature specimens. Head, thorax, and abdomen with cuticular projections (styli), ending in one seta of variable length. The number, distribution, and size of these styli usually characteristic for each genus, although there may be variation within some genera i.e. Berosus (Archangelsky 1994).

Head: Supraorbital styli, one or two pairs (Figure 26C), sometimes absent (Figure 26A). Maxillary palps and mandibles well developed and visible, extending backwards; antennae partially covered by sides of head and pronotum.

Thorax: Pronotum well developed; number of styli variable, usually nine or ten pairs on margins, and one or two pairs on pronotal disc (Figures 26B and D). Mesonotum always with one stylus on each side of scutellum. Metanotum usually with one pair of styli more or less close to midline. Pterothecae well developed, those of elytra cover in part metastemal ones (Figures 25D and E). Legs visible ventrally as three pairs, though sometimes covered partly by pterothecae; meso-metastemal carina of some genera, characteristically long and pointed (some Hydrophilina), easily noted in ventral view.

Abdomen: Nine segmented; first seven segments always with several pairs of styli arranged in a transverse line, variable in number, but usually with two or three pairs; lateral pair close to spiracles (dorsal in view). Pleural styli on segments two to seven, one pair each. Segment eight with or without styli; segment nine without styli, but with one pair of cerci, somewhat varying in shape and length (Figures 80A, 90C, and 99A).

28 CHAPTER 4

GENERAL BIOLOGY OF HYDROPHILOIDEA

Hydrophilids are among the most common and largest of aquatic beetles, they are strong fliers and appear at lights far from the water atracting the attention of people. The common name given to hydrophilids in English speaking countries is “water scavenger beetles”, and the name hydrophilid means “water-loving”. These names are sometimes misleading if we keep in mind that about half of the family (most Sphaeridiinae) are terrestrial, and that almost all known larvae are predators. Also the habitats of many species and even genera are still unknown because they are usually collected at lights or with traps. This shows how little our beetle fauna has been studied from the bionomical or ecological point of view. The reason for this is that most studies are conducted with preserved museum specimens, leaving the biology of these beetles completely unstudied. There are only a few papers summarizing the biology of these beetles, and for many genera the information is scattered throughout the literature. A few references, old but still useful for the New World, are: Richmond (1920) and Wilson (1923a, 1923b), which cover several genera of hydrophiloids in detail; Balduf( 1935) and Miller (1963) give a general account of the family.

Adult hydrophiloids feed mainly on plant material and a variety of decaying organic matter. Many of the aquatic and semiaquatic species have a diet that includes

29 algae and leaves of aquatic plants or grasses in flooded habitats; some of these species also seem to complement their herbivorous diets by preying on snails ( , Hydrophilus spp.) and fish or tadpoles {Hydrophilus spp.) (Balfour-Browne 1910, Balduf 1935). Several species also seem to need a regular intake of animal protein in order to survive and reproduce. These proteins usually come from ingestion of dead animal tissues. Young (1958) found that several species of Tropistemus died after a few days if fed only with plant material, but if their diet was supplemented with dog food, they lived much longer, and reproduced on a regular base.

Eggs are laid in silk cases which have different shapes and degrees of complexity. In the most simple case, females build just a silk web surrounding the eggs (many of the terrestrial genera such as Cercyon, Sphaeridium, etc.). In most of the aquatic and semiaquatic genera females build a two layer egg case; females that make these more complex egg cases apply first a silk layer on the substrate (this layer sometimes can be sac-shaped as in Tropisternus), lay their eggs on this silk layer, and then cover the eggs with a second layer. In those taxa where a ribbon is present, this is attached as the final step of the construction. There are a few genera in which the egg cases are carried by the females. In all these taxa, the egg cases are placed on the ventral side of the abdomen, behind the metathorax; the egg case may be retained in place by the hind legs as in Epimetopus and Spercheus (Bpving & Henriksen 1938, Rocha 1967, and personal observations) or attached to the hind femora by a few silk strands as in Helochares, and Helobata (Bpving and Henriksen 1938, Spangler and Cross 1972, Anderson 1976, Femdndez 1983, and personal observations). The two genera of largest hydrophilids {Dibolocelus and Hydrophilus) construct floating egg cases, using pieces of floating leaves as a support (Wilson 1923a, Archangelsky & Durand 1992a).

30 The time used to construct a case may vary from half hour to about two hours in larger species such as Hydrophilus and Dibolocelus. For some European species times of up to 3 to 5 hours have been recorded (Miger & Lancret 1804, Lyonet 1832).

How often females can lay eggs has not been studied. Tropistemus females mate and lay eggs every two weeks (personal observations); Phaenonotum females are able to lay one or two egg cases every week for a period of several weeks (Archangelsky & Durand, 1992c). The developmental time of the eggs is quite varied. It may be as short as two or three days as in some Cercyon, or up to two weeks in some Tropistemus species. Most hydrophiloid eggsusually hatch in five to ten days.

First instar larvae are usually very active, and in most cases they disperse away from the egg case right after hatching, and before they start feeding. This may be an adaptation to avoid competition and also minimize the risks of cannibalism. Of all the species reared in laboratory, only two did not show cannibalism: Dibolocelus ovatus (which feeds only on snails) and Berosus pugnax (Archangelsky & Durand 1992a, Archangelsky 1994b). There are other reports in the literature about species that do not show tendency to cannibalism (Balduf, 1935), but most observations agree that cannibalism is a very common phenomenon among hydrophiloids. Most larvae are predatory; reports that mention larvae of Sphaeridium (Hafez 1939c) as feeding on dung, but these are mistakes. The larvae I have reared of Sphaeridium fed on fly eggs and maggots. In general, larvae do not seem to be very selective with their diet, feeding on almost anything they can catch; the only exception I have encountered is Dibolocelus ovatus which feeds on snails (Archangelsky & Durand, 1992a), and Hydrochus which until now I have not been able to rear

31 successfully past the first instar. Crustaceans, snails, adults and larvae of other insects (especially dipterans), annelids, small fish and tadpoles have been reported throughout the literature as prey of hydrophiloid larvae (Wilson 1923a, 1923b; Balduf 1935). Angus (1992) reports a couple of species of Helophorus that feed on plant material, but this seems to be the exception with this genus, and the only species I have reared of Helophorus was predatory. Hydrophilids carry on a partial external digestion of the prey. It is common behavior of several species to raise their heads into a vertical position while they eat, and keep the prey within their mouthparts while secreting some digestive fluids. They turn the prey around with their mandibles and maxillae until it is reduced to a soft pulp. During this process they ingest the predigested prey. Wilson (1923a) and Balduf (1935) mention that some species are capable of ingesting solid particles ( Hydrophilus, Hydrochara, Tropistemus). Large species belonging to the genera Hydrophilus and Dibolocelus can feed on snails (Wilson 1923a, Archangelsky & Durand 1992a), but first they have to break the shell. To do this, they first grab the prey within their mandibles, and then the head is thrown backwards until the prey is in contact with the dorsal surface of the abdomen, then the shell is crushed and the soft parts are eaten. Larvae of hydrophilids of the subtribe Hydrophilina are very active swimmers. To achieve this, they use their legs, which have long hairs on the inner margins of the femur and tibiotarsus, which increase their surface. They also produce strong vertical undulating movements of the abdomen while they swim. The larvae of other aquatic hydrophilids usually do not swim, instead they walk on the substrate. Sometime larvae of Berosus avoid predators by producing undulating or twisting movements with their bodies when they are disturbed. Semiaquatic and terrestrial larvae wander or crawl looking for their prey. In the case of some Spaheridiinae, they can easily penetrate

32 within dung or decaying plant tissues using their legs or rows of transversal spines on their abdomens (Archangelsky 1994a). Species of the genus Enochrus have “prolegs” in the abdominal segments 3 to 7, provided with hooks on the anterior end (Bpving and Henriksen 1938, personal observations). Hydrophiloids undergo three larval instars. Only a few Helophorus have been reported to have only two larval instars (Angus 1992). Before pupation, third instar larvae undergo a very distinct period that has been named “prepupal stage”. During this stage, larvae wander around looking for a place to pupate. Larvae in this stage are very active, and refuse to eat. The way in which their bodies turn whitish is characteristic, and the gut and tracheal system, which until then could be seen through the cuticle, become indistinct. The duration of this stage is variable, and it may depend on how long it takes the larvae to find a suitable place for pupation. In the laboratory some species have prepupal stages of only one or two days, but in others it goes on for many days, even a few weeks (this may be due to the laboratory conditions, which can be different from the natural environment). Pupation usually takes place in moist soil. Most of the species reared look for a place with soft soil or sand, and dig a tunnel using their mouthparts and head as a shovel. Once this tunnel is deep enough, they start widening the interior, constructing a pupal chamber. Once this chamber is completed, the prepupae close the entrance. These pupal chambers are not very deep, usually 1 or 2 cm from the surface. Some species instead of digging a pupal chamber in the soil, build one by chewing plant tissues (Dactylostemum, Archangelsky 1994a). They chew cactus and slowly build a chamber that surrounds and protects them from possible predators. Wesenberg-Lund (1913a), Richmond (1920) and Leech & Chandler (1956) report that some species of Enochrus can pupate in water, within a case made by tying algae together.

33 The only known species that pupates in the open is Derallus angustus. Their prepupae wander on Salvinia leaves, preparing a smooth area by cutting a few hairs of the leaf surface. The only protection for these pupae are their cryptic coloration (green), and the short duration of the pupal stage (only two days).

Buhk (1910) and Balduf (1935) describe the way in which prepupae of Spercheus emarginatus pupate, which is very different from other hydrophiloids. According to their descriptions, the prepupa picks up particles of soil with its mandibles and attaches them to its back; the prepupa then climbs up a stem, fastens itself to it and curls up under this cover of soil. Once in the pupal chamber the prepupae can pupate almost immediately, or they can wait a few days before pupation. Once the adults are completely formed, they usually stay a day or two in the pupal chamber before emerging; this allows them to harden their exoskeleton before leaving the pupal chamber.

34 CHAPTER 5

SYSTEMATIC SECTION: A REVISION OF THE IMMATURE STAGES OF THE NEW WORLD HYDROPHILOIDEA

Key to the New World larvae of Hydrophiloidea

Preparing a key for larval stages of Hydrophiloidea found in a large and diverse geographical region such as the New World is not an easy task, and several of the problems faced during its construction are mentioned below. This is the first key for the New World that includes aquatic, semiaquatic, and terrestrial genera; the most recent keys for North America usually include only the aquatic and semiaquatic members of this superfamily (Pennak 1978, Brigham & Brigham 1982, Merritt & Cummins 1984, 1996). I have not been able to see larvae of all the genera included in the key, so some of the information used to build it comes from the original drawings and descriptions, which in a few cases are not as detailed as one would like, and sometimes incomplete. Some of these original descriptions are based on only one of the larval instars (either first or third), and this can lead to misidentifications because it is common for some characters, such as size or shapes of structures, to vary among different instars. For those larvae of which I have seen the different larval stages, comparative notes among

35 TABLE 3. New World Hydrophiloidea. Genera studied for this Dissertation (* = genera whose immatures were studied; ** = genera in which the information has been obtained from the literature).

Family Genus

Helophoridae * Helophorus orientalis Motschulsky Epimetopidae * Epimetopus trogoides (Sharp) Georissidae * Georissus sp. Hydrochidae * Hydrochus rufipes Melsheimer Spercheidae * Spercheus emarginatus (Schaller) Hydrophilidae * Sperchopsis tessellata (Ziegler) * Ametor scabrosus (Horn) ** Anticura flinti Spangler * Berosus corrini Wooldridge * B. hoplites Sharp * B. pugnax LeConte * Derallus angustus Sharp * Chaetarthria sp. ** Guyanobius adocetus Spangler * Paracymus subcupreus (Say) * Crenitis sp. ** Anacaena infuscata (Motschulsky) * Notionotus liparus Spangler * Laccobius minutoides d’ Orchymont * Oocyclus sp. * Helochares maculicollis Mulsant ** Helobata larvalis (Horn) * Enochrus ochraceus (Melsheimer) * E. cinctus (Say) * E. hamiltoni (Horn) ** Helocombus bifidus (LeConte) * Cymbiodyta vindicata Fall ** Chasmogenus nitescens (Fauvel)

36 TABLE 3 (Cont.). New World Hydrophiloidea. Genera studied for this Dissertation (* = genera whose immatures were studied; ** = genera in which the information has been obtained from the literature).

Family Genus

* Hydrobius melaenus (Germar) ** Hydramara argentina (Knisch) * Tropistemus lateralis (Fabricius) * T. spp. ** Hydrobiomorpha casta (Say) * Hydrochara caraboides (Linnaeus) * Dibolocelus ovatus (Gemminger & Harold) * Hydrophilus triangularis Say * H. piceus (Linnaeus) * H. sp. ** Cyclorygmus lineatopunctatus d’Orchymont * Phaenonotum exstriatum (Say) * Ph. puncticolle Bruch * Dactylostemum cacti (LeConte) * D. spp. * Cercyon praetextatus (Say) * Pelosoma sp. * Cryptopleurum minutum (Fabricius) * Pemelus costatus (LeConte ** Megastemum obscurum (Marsham) * Sphaeridium scarabaeoides (Linnaeus) * S. bipustulatum (Fabricius)

37 them are provided in the section with taxonomic descriptions. When trying to identify specimens, I recommend consulting the generic diagnosis of the larvae before assigning them a name. In this key I have tried to use characters that do not tend to vary much among the different larval instars. A list of the species examined for the construction of the key, and the generic diagnosis is presented in Table 3. In many cases larvae have been assigned to a certain genus based on associations. This means larvae that were collected in the field associated with adult hydrophiloids. In many cases these associations may be correct, but there is always room for error. This is the reason why it is preferable to rear larvae from adults. Finally, due to poor knowledge of immature stages, most of the information available comes from only one or may be two species within a genus, and sometimes these are species from different biogeographic regions (i.e. Spercheus, from the Palaearctic region or Chasmogenus, from New Zealand). Some of the hydrophiloid genera have more than a hundred described species, so it is possible that we may be underestimating the variation and diversity within these genera (i.e. Berosus, Bertrand 1972, Archangelsky 1994b).

I Stipes of maxilla with a well developed lacinia (Fig. 13C); distal end of mandible bifid (Fig. 12B, C); five stemmata on each side of the head SPERCHEIDAE...... Spercheus V Stipes without or with a strongly reduced lacinia; distal end of mandible single; usually six stemmata on each side of the head (they may look like one in some third instars)...... 2

38 2 Abdomen with 9 complete segments; segment 10 terminal, small but distinct; no spiracular atrium present (Figs. 1 A, 6A ) ...... 3 2’ Abdomen with 8 complete segments, segments 9 and 10 reduced and modified into a spiracular atrium (Figs. 9A, 14A) (except for Berosus with only eight visible abdominal segments and no spiracular atrium, Fig. 23A) ...... 5 3 Legs well developed, 5-segmented ...... 4 3’ Legs reduced, 3-segmented (Fig. 8A ) GEORISSIDAE ...... Georissus 4 Urogomphi small, 1-segmented; stemmata closely aggregated (based on 1st instar larvae); segments eight and nine each with a pair of long, fleshy postero-lateral projections (Figs. 4A, C); abdominal tergites and stemites absent EPIMETOPIDAE ...... Epimetopus 4’ Urogomphi long, 3-segmented (Fig. 1C); 6 stemmata on each side of the head, well separated; no fleshy projections on abdominal segments eight and nine; abdominal tergites and stemites present (Fig. 1 A) HELOPHORIDAE ...... Helophorus 5 Mandibles with a spinose pseudo-molar area at the base, also bearing a seta at the apical end (Fig. 10E); gula well developed and distinct; antennae inserted nearer to antero-lateral angle of the head than the mandibles; lacinia present (Fig. 10B) HYDROCHID AE...... Hydrochus 5’ Mandibles without pseudo-molar area, seta on apical end absent; gula reduced; antennae inserted further from antero-lateral angle of head than mandibles (Fig. 14B); lacinia absent HYDROPHELIDAE ...... 6 6 Spiracular atrium absent; at least some of the abdominal segments with long lateral tracheal gills (Figs. 23A, C ) ...... Berosus 6’ Spiracular atrium present; projections from the thoracic and abdominal segments present or absent, but never functioning as tracheal gills ...... 7

39 7 Hypopharyngeal lobe reduced or absent...... 15 7’ Hypopharyngeal lobe well developed, like a pubescent tongue originating at the base of the labium on the left side (Figs. 89D, 93A) ...... 8 8 Legs small, but 5-segmented (Fig. 109C) ...... 9 8’ Legs reduced or absent, at most 3-segmented (Fig. 96B) ...... 10 9 Ligula absent (Fig. 89E) ...... Dactylostemum A 9’ Ligula may be small but always distinct (Fig. 93A, 109A) ...... 10 10 Hypopharyngeal lobe large, as long or longer than labial palpi (Fig. 109B); eighth abdominal segment with two pairs of fleshy lateral projections (Fig. 108D); mandibles asymmetrical, without inner teeth (Figs. 110D, E ) Sphaeridium 10’ Hypopharyngeal lobe shorter, not reaching base of labial palps (Fig. 93A); eighth abdominal segment without fleshy projections; mandibles asymmetrical, with two inner teeth (Figs. 92B, E) ...... Dactylostemum B 11 Legs extremely reduced, as a small bump or tubercle with a few spines ...... Cryptopleurum 11 ’ Legs reduced, but 3-segmented (the coxa may look membranous), very small but distinct (Fig. 96B) ...... 12 12 Pleural areas of abdomen strongly lobed (Fig. 106A) ...... Megastemum 12’ Pleural areas of abdomen smooth or slightly lobed (Figs. 94A, 103 A) ...... 13 13 Outer margin of stipes with long, flat spines projecting outwards (Fig. 104D); sensory appendage of antenna half the length of third antennal segment (Fig. 1040) (third instar larva)...... Pemelus 13’ Outer margin of stipes may be pubescent (Figs. 95F, 98B), but never with long, flat spines; sensory appendage of antenna longer (Fig. 95C) ...... 14

40 14 Dorsal plate of eighth abdominal segment subquadrate, without apical projections (Fig. 97C) ...... Pelosoma

14’ Dorsal plate of eighth abdominal segment suboval, with one, three or five apical lobes or projections (Fig. 94C) ...... Cercyon

15 Legs reduced, without claw; labium with a large, round ligula (Fig. 31C) ...... Chaetarthria

15’ Legs 5-segmented, with well developed claw; labium with or without ligula, but never round as above ...... 16

16 Meso- and metathorax, and abdominal segments 1 through 7 with several pairs of long setiferous projections (Fig. 27A) ...... Derallus

16’ Without those long setiferous projections ...... 17

17 Mandibles strongly asymmetrical, different in shape or number of inner teeth (Figs. 45B,E; 56C,E) ...... 18

17 ’ Mandibles symmetrical or nearly so, both with similar shape and number of inner teeth...... 23

18 Ligula absent (Fig. 46D); labroclypeus asymmetrical, left epistomal lobe large, considerably exceeding nasale and covering basal third of left mandible (Figs. 44B, 45 A)...... Laccobius

18 ’ Ligula present; labroclypeus symmetrical, if asymmetrical with epistomal lobes at most slightly exceeding nasale ...... 19

19 Labroclypeus asymmetrical (Fig. 56A), with a row of 6 or 7 stout teeth ...... Enochrus

19’ Labroclypeus symmetrical (Figs. 69A, 79B) or slightly asymmetrical (Hydrophilus without teeth)...... 20 20 Head subspherical; frontal sulci U-shaped (Figs. 76B, 79B) ...... 21

20 ’ Head subquadrangular; frontal sulci V-shaped (Fig. 68B) ...... 22

41 21 Left mandible with a small tooth (Fig. 80E); setiferous lateral lobes on abdominal segments very short (Fig. 79A) ...... Hydrophilus 21 ’ Left mandible without teeth (Fig. 77B); abdominal segments 1 through 8 with one pair of long lateral setiferous lobes (Fig. 76A) ...... Dibolocelus 22 Antennae shorter than mandibles (Fig. 61 A); right mandible with two large inner teeth, left with only one (Fig. 6IB); labroclypeus with five large teeth ...... Chasmogenus 22’ Antennae longer than mandibles (Fig. 68B); right mandible with one large and two small inner teeth, left with one large and one or two small ones (Figs. 69C,D); labroclypeus with six or seven small teeth...... Tropistemus 23 Abdominal segments with prominent, fleshy lateral projections ...... 24 23’ Abdominal segments without fleshy projections ...... 25 24 Meso- and metathorax also bearing projections (Fig. 37A) ...... Crenitis 24’ Projections restricted to abdominal segments (Fig. 73A) ...... Hydrochara 25 Mandibles with three distinct inner teeth (Fig. 35C) ...... 26 25’ Mandibles with two distinct inner teeth (Fig. 86B) ...... 32 26 Labroclypeus (nasale) with four teeth (Fig. 35A) ...... 27 26’ Labroclypeus with five teeth (Sperchopsis with middle one very small but distinct) (Figs. 15A, 64A) ...... 29 27 Frontal sulci Y-shaped (Fig. 17B); labroclypeus asymmetrical (Fig. 18A); metathoracic tergites large and subrectangular (Fig. 17A) ...... Ametor 27’ Frontal sulci U-shaped or lyriform (Figs. 34B, 40A); labroclypeus slightly asymmetrical; metathoracic tergites smaller and narrow (Fig. 34A, 40A) ...... 28

42 28 Mentum with numerous cuticular spines widely distributed (Fig. 41C); frontal sulci U-shaped...... Anacaena 28’ Mentum with a few central, large cuticular spines (Fig. 35D); frontal sulci lyriform ...... Paracymus 29 Labroclypeus symmetrical or nearly so, with teeth arranged on a semicircle, median ones projecting farther than lateral ones (Figs. 15A, 33B) ...... 30 29’ Labroclypeus distinctly asymmetrical, right side projecting farther than left side (Figs. 64A, 67A) ...... 31 30 Frontal sulci Y-shaped (Fig. 14B); ligula shorter than labial palpi (Fig. 15E); Eastern Nearctic...... Sperchopsis 30’ Frontal sulci U-shaped (Fig. 32B); ligula longer than labial palpi (Fig. 33D); Neotropical ...... Guyanobius 31 Ligula twice as long as basal segment of labial palp (Fig. 65A); Nearctic ...... Hydrobius 31 ’ Ligula shorter than basal segment of labial palp (Fig. 67E); Neotropical ...... Hydramara 32 Labroclypeus without any teeth or projections (Fig. 54A) ...... Helobata 32’ Labroclypeus with at least one median projection (Fig. 86A) ...... 33 33 Labroclypeus with three or less teeth...... 34 33’ Labroclypeus with more than three teeth (they may be inconspicuous as in Hydrobiomorpha)...... 36 34 Labroclypeus with two teeth (Fig. 21 A); frontal sulci Y-shaped (Fig. 20B), with short coronal sulcus; Austral South America ...... Anticura 34’ With one or three teeth; frontal sulci never Y-shaped ...... 35

43 35 Labroclypeus with one median tooth, which can be trifid (Fig. 86A); frontal sulci U-shaped (Fig. 85B); abdominal segments without swollen pleurae or tubercles Phaenonotum 35’ Labroclypeus with three teeth, lateral ones bifid (Fig. 82C); frontal sulci never U- shaped (Fig. 82B); abdominal segments with swollen pleurae and or conical tubercles (Fig. 82A) ...... Cylorygmus 36 Frontal sulci Y-shaped; legs long, at least twice as long as mandibles (Fig. 71 A); mentum twice as wide as prementum (Fig. 71C) ...... Hydrobiomorpha 36’ Frontal sulci U-shaped; legs short, subequal to mandibles in length; mentum at most slightly wider than prementum ...... 37 37 Labroclypeus wit 5,6, or 7 defined teeth, frontal sulci as in Fig. 60B ...... Helochares 37’ Labroclypeus with more than 7 teeth, lateral ones well defined, but middle ones smaller and less distinct ...... 38 38 Labroclypeus with three or four distinct teeth on the left, and two on the right (Fig. 59C), those on the right projecting farther than left ones ...... Cymbiodyta 38’ Labroclypeus with two distinct teeth on each side (Fig. 58D), right ones not projecting farther than left ones ...... Helocombus

Diagnostic descriptions

This section provides diagnostic descriptions of the egg cases, larvae, and pupae of the genera included in this study; when possible, comparative notes between the different larval instars have been included. Information on the distribution, number of species and bionomics within each genus is included. Also the New World species

44 with known immatures are listed together with the pertinent references, and a list of the species examined for each generic diagnosis has been added.

HELOPHORIDAE

1- Helophorus Fabricius (Figures 1-3)

Egg case: Buried in mud, sand or among algae or plant debris in the littoral zone, near the water. The cases are bag-shaped, with a more or less elongated mast that is usually exposed. The substratum on which they are laid adheres to the egg case. Angus (1973, 1992) recognizes four different kinds of egg cases, according to the length and shape of the mast: tubular, leaflike, trailing thread-like, and tube-threads. There are several eggs in each case.

Larva: Head capsule: Subquadrangular; labroclypeus symmetrical; nasale prominent, triangular; lateral lobes of the epistome large and projecting farther than nasale. Frontal sulci converging towards the occipital foramen, but not fusing, therefore there is no coronal sulcus. Six stemmata on each side. Gular sclerite absent; no cervical sclerites in dorsal view.

Antennae: Three-segmented; basal segment as long as second; third segment about half the length of middle segment. Second segment carrying two distal sensory appendages on the outer margin.

45 Mandibles: Symmetrical, with two inner teeth; distal inner margin of mandible serrated. There is a tuft of a few strong setae at the base of the distal inner tooth. A penicillus-like structure is present at the base of the mesal edge of the mandibles.

Maxillae: Five-segmented. Cardo small, subdivided and subtriangular; stipes long and wider than remaining segments; palpifer almost as long as stipes, carrying an apical galea. Palp three-segmented, second segment slightly longer than the other two.

Labium: Formed by prementum and mentum, with a membranous submentum. Prementum distally cleft in two short branches; mentum with dorsal cuticular spines. Labial palps two-segmented, basal segment shorter than distal one; ligula absent.

Thorax and legs: Pro-, meso-, and metathorax each covered by large dorsal shields which have a sagittal line. Legs five-segmented, long, easily seen in dorsal view.

Abdomen: First nine segments well developed; 10th segment small and placed ventrally. Segments one to eight with a pair of subquadrangular dorsal plates in the middle, and two narrower plates on either side. There are two lateral sclerites (pleurites) on each side. Ventrally there are six to eigth small plates. Urogomphi long, three- segmented; distal segment carrying a very long seta. Segment nine with a large dorsal plate.

Spiracles: Nine pairs of functional spiracles, one mesothoracic and eight abdominal.

46 Pupa: Head: With two supraorbital styli. Thorax: Pronotum with 14 to 16 styli, all on the margins, none on disc. Mesonotum and metanotum each with one pair of styli near midline. Abdomen: Segments one to seven with a transverse row of four styli on tergum; segments two to seven with one stylus on each pleura. Segment eight with two tergal styli on posterior margin, and one stylus on each pleura. Segment nine with one pair of cerci.

Number of species and distribution: 41 species known from the Nearctic Region, absent in the Neotropics. Six of those species are Holarctic. Immature stages of seven Nearctic and Holarctic species have been described: H. (H.) grandis, H. (R.) orientalis, H. (R.) splendidus, H. (R.) oblongus, H.(R■) lacustris, H. (C.) tuberculatus, and H. (G.) sibiricus. Angus (1992) has detailed information on Palaearctic Helophorus, including many larval forms; he also has a larval key to 45 of those species. Richmond (1920) describes the larva and life cycle of H. lacustris and the pupa of H. aquaticus.

Bionomics: Helophorus species typically can be found at the water’s edge, in moss, algae, or among the leaf litter. The egg cases are usually buried in the littoral zone, and larvae can be collected in the same habitats, where they wander looking for prey. Pupation takes place in pupal chambers dug in the soil. Some Old World species have herbivorous larvae (Petherbridge 1928, Rodionov 1928, Petherbridge & Thomas 1936, Angus 1992). These vegetarian iarvae have been reported as pests of turnips, swedes, and wheat. There are typically three larval instars, as in all hydrophiloids, but there are two Palaearctic species that have only two larval instars, which seem to correspond to the first and third instars of the other Helophorus (Angus 1992).

47 Additional comments: Some Mesozoic fossils resemble Helophorus species. Ponomarenko (1977) describes the fossil genus Mesohelophorus from the Lower of Transbaikal. It is also interesting to mention that remains from extant species are common from the British Pleistocene, between 30,000 and 120,000 years old (Angus 1992).

EPIMETOPIDAE:

1- Epimetopus Lacordaire (Figures 4-5)

Egg case: Bag-shaped, yellowish, and opaque. It has no mast, and is carried by the female underneath the abdomen; it is kept in place by the hind legs (femora and tibiae) Rocha (1967) and personal observations. Egg cases of Epimetopus trogoides were dissected by Rocha (1967), and each contained 17 eggs. Schwarz and Barber (1917) also mention females carrying egg cases.

Larva: Head capsule: Subquadrangular; labroclypeus symmetrical, nasale with a bilobed apex. Lateral lobes of epistome well developed, with four large modified setae or projections pointing mediad. Frontal sulcus U-shaped, coronal sulcus very short, difficult to see. One pair of ocular spots, with stemmata closely aggregated (Costa et al 1988, Hansen 1991). Gular sclerite absent. Cervical sclerites absent.

48 Antennae: Three-segmented; basal segment much shorter than second; second segment carrying one sensory appendage on the outer margin, as long as third antennal segment; third segment very short.

Mandibles: Symmetrical, with distal inner margin serrated. Basal half of the mandible forming a groove, with a flat dorsal tooth, and a stout median tooth pointing backwards; basal third of mandible coarsely serrated, with short spines. Base of median tooth with a few large projections, pointing backwards.

Maxillae: Five-segmented; cardo large, subdivided and subtriangular; stipes wider and longer than any of the other segments, poorly sclerotized on dorsal side, with five setae on inner margin, some with several short spicules; palpifer shorter than palp, subquadrate, carrying a small apical galea; palpi three-segmented, distal segment slightly longer than first or second. Dorsal surface of stipes and palpifer with a few small cuticular spines.

Labium: Formed submentum, mentum, and prementum. Submentum large, subtrapezoidal; mentum small, subquadrate, with few small cuticular spines on dorsal surface; prementum shorter, wider than long. Palpi two-segmented, basal segment half the length of second. Ligula absent.

Thorax and legs: Pronotum covered by a large dorsal plate, poorly sclerotized, with sagittal line, more sclerotized than abdominal segments. Mesonotum with two small subtriangular tergites; metanotum with two smaller tergites; plates of meso- and metanotum poorly sclerotized, difficult to see. Legs five-segmented, visible in dorsal view.

49 Abdomen: Scarcely sclerotized, ten-segmented. First nine segments well developed, segments one to seven similar in size and shape, subdivided by a small transverse fold, each with a short spiracular lobe on each side. Posterior margin of eighth segment with two long lateral finger-like projections, and a pair of short spiracular lobes. Segment nine slightly smaller than preceding ones, also with a pair of long finger-like projections on distal end; urogomphi short, one-segmented. Segment ten small, visible only in ventral view. No spiracular atrium present.

Spiracles: Present, one pair mesothoracic; abdomen with eight pairs, all functional, biforous. Spiracles positioned on short lateral lobes.

Pupa: Unknown.

Number of species and distribution: About 20 described species, Neotropical and southern Nearctic in distribution. The only species with described larvae (first instars) is E. trogoides from Brasil (Rocha 1967, 1969; Costa et al 1988). Hansen (1991 has some remarks and corrections to the original descriptions.

Bionomics: Little is known about species of this genus; they seem to be rare and difficult to find. Epimetopus species seem to be aquatic or semiaquatic, living among the vegetation on margins of streams, where they crawl about. E, thermarum has been collected by Schwarz and Barber (1917) at the margins of warm streams (up to 37-38° C) in Arizona, adults seem to be common during early summer, larvae were also collected but these authors, but most of the material was destroyed during a fire.

50 GEORISSIDAE

1- Georissus Latreille (Figures 6-8)

Egg case: Unknown.

Larva: Head capsule: Subquadrangular; labroclypeus symmetrical, nasale prominent, triangular; lateral lobes of epistome well developed, projecting farther than nasale, with strong spines on mesal margin. Frontal sulci originated at the sides of the antennae (apparently not touching the antennal foramen); frontal sulci converging towards the occipital foramen, but not fusing, therefore no coronal sulcus present. Six stemmata on each side.

Antennae: Three segmented; basal segment large and longer than other two together; second segment carrying two distal sensory appendages, inner one almost as long as third segment, outer one much shorter. Antennal foramens placed on the sides of the head, extending further (laterally) than point of articulation of mandibles.

Mandibles: Symmetrical, with two inner teeth; distal inner margin serrated. There is a tuft of strong setae at the base of the basal inner tooth, and a penicillus-like structure at the base of the mesal edge.

Maxillae: Five segmented; cardo small and subdivided in two sclerites. Stipes wide and short; palpifer long, twice the length of stipes, carrying a reduced, membranous apical

51 galea. Palp three segmented, basal two segments of about the same length, distal one slightly longer.

Labium: Formed by submentum, prementum and mentum. Submentum large, subtrapezoidal wider at base; mentum subquadrate, with small cuticular spines; prementum shorter than mentum, distally cleft in two short branches, with short cuticular spines at base. Ligula absent, palpi two-segmented.

Thorax and legs: Pronotum covered by a large tergite, sagittal line present; mesothorax wider, with two pairs of narrow tergites on disc and three small suboval sclerites on each side; metathorax with a transverse row of eight small suboval sclerites.

Abdomen: Ten-segmented; first eight segments similar in shape, tapering towards the distal end; each with three pairs of small oval tergites; segment eight similar in shape, but with only two pairs of tergal sclerites; segment nine smaller, carrying a median plate and a pair of small conical, 1-segmented cerci.; segment ten broad and short, visible in dorsal view, with a small median tergal plate and two smaller apical tergites. Pleural areas of segments one to nine with a pair of small oval plates.

Spiracles: Nine pairs of biforous spiracles; one mesothoracic pair and eight abdominal (segments 1 to 8). No spiracular atrium present on segment eight.

Pupa: Unknown

Number of species and distribution: About 72 species Worldwide (Hansen 1991). In the New World there are two species known from North America, and two from

52 Central and South America. Until now the only species for which the larva had been described was Georissus crenulatus, from Germany (van Emden 1956); the larva described here is from Montana.

Bionomics: Semiaquatic species, living at the margins of streams, among the mud, sand and algae. Both adults and larvae occur in the same habitats. The adults are usually covered by a coating of mud, therefore difficult to see.

Additional comments: Until recently the position of georissids has been a subject of discussion. They have been placed with different groups of Coleoptera, such as , , Lathridiidae, Thoricidae, , and also Hydrophilidae (Erichson 1847, Kolbe 1901, Ganglbauer 1904, Sharp & Muir 1912, Meixner 1935, Blackwelder 1944). Currently they are placed within the Hydrophiloidea, based mainly on detailed studies of the adults and the larvae (Crowson 1950, van Emden 1956, Hansen 1991).

HYDROCHIDAE

1- Hydrochus Leach (Figures 9-10)

Egg case: Small and flat, irregular in shape, with a short flat mast on one end. It carries only one egg. The egg cases are attached to plants, tree roots, or pieces of bark or branches at the waters edge (Richmond 1920, personal observations).

53 Larva: Head capsule: Subquadrangular, slightly wider than longer. Labroclypeus symmetrical, without prominent nasale; lateral lobes of epistome poorly developed. Frontal sulci extending from base of antennae to occipital foramen, without coming in contact; coronal sulcus absent. Stemmata small, six on each side of the head. Gular sclerite present, but small, between the labium and the occipital foramen.

Antennae: Three-segmented, basal segment very large, longer than other two combined. Second segment carries a sensory appendage which is as long as the third segment (at least on first instar larvae); it also carries a large semicircular lobe on inner margin, covered by stout spines.

Mandibles: Very characteristic, symmetrical. Distal part very thin and strongly curved, with inner margin roughly serrated; tip of mandible with a short seta. The two inner teeth are close to the base of the mandible; distal one long and slender, basal one short and acutely pointed. Base of mandible with a spinose lobe, considered a “pseudomolar area” by Bpving and Henriksen (1938).

Maxillae: Five-segmented; cardo large, subdivided and subtriangular. Stipes large, bearing a small inner tubercle carrying by several long setae (reduced lacinia). Palpifer also large, slightly shorter than stipes, carrying a small apical galea; inner and dorsal surface of palpifer and stipes covered by small spines. Palp three-segmented, two basal segments short and broad, distal segment longer and conical in shape.

Labium: Formed by submentum, mentum and prementum. Submentum large, subquadrate; mentum short, subtrapezoidal, closely attached to submentum, with

54 several long spines on distal margin; prementum longer than wide. Palps two- segmented, basal segment short distal one composed of three lobes. Ligula absent.

Thorax and legs: Pronotum covered by a large dorsal plate, sagittal line present; meso- and metathorax similar in size and shape, each with a pair of suboval tergites. Legs well developed, five segmented and visible in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in size and shape, tapering towards the end, lacking dorsal or ventral plates. Segments eight and nine modified, forming a spiracular atrium; segment eight with a large dorsal plate, and two sclerotized lobes on each side; segment nine with five sclerotized lobes, carrying a pair of two-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Unknown

Number of species and distribution: About 90 species described from all biogeographical regions. South America has 12 species excluding the Patagonian Andes (Oliva 1992); there are 50 in North and Central America. Until now the only species for which the first instar larvae and egg case had been described was Hydrochus squamifer LeConte (Richmond 1920, Bpving & Henriksen 1938). The larva described here is that of H. rufipes.

55 Bionomics: Both adults and larvae are aquatic, but not swimmers; they can be found in a variety of situations such as on aquatic plants ( Elodea, Ceratophyllum, Azolla, etc.) or on tree roots or branches on the margins of pools or slow moving water. They are slow in their movements, and the adults usually feign death when disturbed. Larvae and adults crawl among the vegetation, the adults feeding on algae, the larval diet still remains uncertain.

Additional comments: There is one hydrophiloid genus from the Mesozoic, Mesospercheus, that has characters relating it to both Spercheus and Hydrochus (Ponomarenko 1977), although most of the characters point to a closer relationship to Spercheus. The original description of H. squamifer by Richmond (1920), mentions the larva as having the thoracic and abdominal segments covered by complete tergal and sternal plates, something not seen in other hydrophiloids (but present in hydraenids), this was not observed in the larva of H. rufipes, so I consider those plates as a misinterpretation by Richmond.

SPERCHEIDAE

1- Spercheus Kugelann (Figures 11-13)

Egg case: Made of a tough layer of silk, grayish in color. Carried by female on underside of abdomen; as eggs develop it swells beyond the sides of the elytra (Fowley 1882). Kept in place by hind legs (femora and tibiae). Number of eggs between 80 and 100.

56 Larva: Head capsule: Subpentagonal; labroclypeus symmetrical, with a trapezoidal nasale; lateral lobes of epistome not developed. Frontal sulci converging towards the occipital foramen; coronal sulcus absent. Five stemmata on each side of head. Gular sclerite large and subquadrate; no cervical sclerites on dorsal view.

Antennae: Three segmented; basal segment slender, as long as other two combined, inserted more laterally than the mandibles; segments two and three similar in length and also slender; distal sensory appendage of segment two reduced, appearing as a small round projection.

Mandibles: Symmetrical, apex bifid; mesal margin concave in cross section, with a small inner tooth on dorsal side, and a row of long setae on ventral side.

Maxillae: Five-segmented. Cardo large, subdivided and contained in a deep emargination of the head capsule. Stipes short and wide, carrying a large lacinia on inner margin; lacinia with hollow mesal surface surrounded by strong setae and spines. Palpifer as long as stipes, but more slender, carrying a long apical galea. Palpi three- segmented, basal segment the shortest.

Labium: Formed by submentum and a segment made by the fusion of mentum and prementum. Submentum small, trapezoidal; mentum + prementum large, piriform, with a row of long spines on each margin. Ligula short and conical; labial palps two- segmented, basal segment fused to prementum.

57 Thorax and legs: Pronotum strongly sclerotized, with sagittal line. Mesonotum, metanotum, and all thoracic sternites unsclerotized. Meso- and metathorax with a transverse row of setiferous lobes. Legs long, five-segmented, visible in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven with transversal rows of setiferous lobes, similar to those of thorax; segment eight with a small tergal plate, forming the roof of the spiracular atrium; segment nine reduced, also part of the atrium.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous, very small and difficult to see; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Described by Cussac (1852), but the description is vague and does not provide diagnostic characters (Bpving & Henriksen 1938).

Number of species and distribution: This is a small genus, with only 16 species, of which only one occurs in the New World (Argentina, Bolivia, and Brazil), Spercheus fimbricollis Bruch 1915. The only species with described immatures is S. emarginatus from the Palaearctic region, the immatures are described by Cussac (1852), Fowler (1882), and Bpving & Henriksen (1938).

Bionomics: Spercheus species are usually found in stagnant waters, with dense vegetation. Both adults and larvae crawl on the vegetation, and are capable of walking on the underside of the water’s surface. Larvae are predatory, feeding on other small

58 invertebrates, they can be cannibalistic (Fowler 1882), and according to B0ving & Henriksen (1938) they can also feed on drifting organic remains. Females carry the egg cases on the underside of the abdomen, and when disturbed they are able to contract the abdomen and in this way protect the lateral edges of the egg case with the sides of the elytra. Females seem to be able to produce up to four egg cases during the spring (Bpving & Henriksen 1938).

Additional comments: There are some Mesozoic fossils that seem to be related to Spercheus (Ponomarenko 1977); one of them is Mesospercheus, mentioned above (see comments on Hydrochus). Larvae of Spercheus emarginatus have a large proventriculus located in the occipital region, it is strongly musculated and sclerotized; no other hydrophiloid larvae I have dissected have such well developed proventriculus.

HYDROPHILIDAE

Hydrophilinae:

1- Sperchopsis LeConte (Figures 14-16)

Egg case: Bag-shaped, white. Without mast, but a marginal flap surrounds the cap. Method of attachment unknown. From the only known egg case, 17 larvae emerged (Spangler 1961).

59 Larva: Head capsule: Quadrangular, labroclypeus slightly asymmetrical; nasale with five teeth, four large lateral ones, and a small middle one; lateral lobes of epistome large and rounded. Frontal sulci converging and fusing before occipital foramen; coronal sulcus short. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, small, rectangular.

Antennae: Three-segmented; basal segment longer than other two combined; second segment with a row of short spines on inner margin, and one distal sensory appendage, shorter than third antennal segment.

Mandibles: Symmetrical, with three inner teeth at midlength; basal tooth much smaller than distal two.

Maxillae: Five segmented. Cardo small, irregularly shaped, subdivided. Stipes longer and wider than remaining segments, with seven stout setae on inner margin, and a group of spines at the base; palpifer short, incompletely sclerotized, carrying an inner galea. Palp three-segmented, middle segment as long as the other two combined.

Labium: Formed by submentum, mentum, and prementum. Submentum wide and rhomboid; mentum subquadrate, with dorsal surface covered by spines and numerous setae on the anterior margin; prementum also subquadrate, carrying a pair of two- segmented palpi and a very long ligula; basal palpal segment shorter than distal one.

Thorax and legs: Pronotum strongly sclerotized, with sagittal line; mesonotum and metanotum with a pair of small subtriangular sclerites. Prosternal sclerite large,

60 subrectangular, without sagittal line. Legs five-segmented, long, visible in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in shape, with three or four transverse folds and several transverse rows of setose tubercles; epi- and hypopleurites strongly lobed; segment one with a pair of small suboval plates. Segment eight forming the spiracular atrium, with a large oval plate that covers most of the tergum. Segment nine trilobed, with one pair of short one- segmented urogomphi.

Spiracles: Nine pairs, one mesothoracic, and eight abdominal. Mesothoracic and first seven abdominal spiracles biforous but non-functional; last abdominal pair large, annular, within the spiracular atrium.

Pupa: Head: Without supraorbital styli. Thorax: Pronotum with 24 styli, 20 along the margins, and four on disc; mesonotum with one stylus on each side of scutellum; metanotum with one pair of styli close to midline. Abdomen: First abdominal segment with two pairs of styli, one close to midline and one lateral; segments two to seven with six pairs, one pair close to midline and two other pairs lateral; segment eight with two pairs of styli; segment nine lacking styli, but with a pair of long cerci.

Number of species and distribution: Monotypic genus, the only described species, Sperchopsis tessellata (Ziegler 1844), has an eastern Nearctic distribution. The immatures were described by Spangler (1961).

61 Bionomics: Spangler (1961) describes the habitat and behavior of the larvae in detail. This is one of the few hydrophilid species that lives in margins of cold and rapid flowing streams. They seem to like undercut banks with hanging roots and vegetation. Apparently the eggs are laid on the sandy banks (the only known egg case had sand grains adhered on its surface). Larval development is slow for hydrophiloids (over three months). As most other hydrophiloids, larvae are predaceous, and also cannibalistic. Pupation takes place in pupal chambers dug in the sand.

2- Ametor Semenov (Figures 17-19)

Egg case: Unknown

Larva: Head capsule: Subquadrate; labroclypeus asymmetrical; nasale prominent, with four teeth, left one shorter and slightly apart from other three; lateral lobes of epistome rounded, not projecting further than nasale. Frontal sulci converging towards occipital foramen, coming together before reaching it; coronal sulcus short. Six stemmata on each side of head. Gular sclerite absent, cervical sclerites present, suboval.

Antennae: Three segmented, short; basal segment as long as other two combined. Second segment carries a short distal sensory appendage, difficult to see; last segment short.

62 Mandibles: Symmetrical, with three inner teeth at midlength; basal one very small, two distal ones larger.

Maxillae: Five-segmented. Cardo small, subdivided in two subtriangular sclerites. Stipes wide and longer than other segments combined, with a row of six strong setae on mesal margin, and a group of spines at the base. Palpifer short and broad, incompletely sclerotized, carrying an apical galea as long as first segment of palpus. Palpi three-segmented, segment two as long as the other two combined.

Labium: Formed by submentum, mentum, and prementum. Submentum subrhomboidal, wider than other two segments; mentum subtrapezoidal,, covered by cuticular spines, with a group of setae on antero-lateral angles; prementum subquadrate, carrying the palpi and a long ligula. Palpi two-segmented, basal segment very short; ligula as long as second palpal segment.

Thorax and legs: Pronotum strongly sclerotized, with sagittal line; mesothorax and metathorax each with two pairs of small tergites, both with sagittal lines. Prostemal sclerite large, subrectangular, with incomplete sagittal line. Legs five-segmented, visible in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven each with a pair of small oval tergites, and three or four transverse folds, anterior and posterior folds with a transverse row of four setose tubercles; epipleurites and hypopleurites with prominent lobes. Segment eight covered by a large and posteriorly crenulated tergite, forming part of the spiracular atrium. Segment nine trilobed, covered by eighth tergite. Urogomphi small, conical, one-segmented.

63 Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With one pair of supraorbital styli on inner margin of each eye. Thorax: Pronotum with 20 styli along the margins, none on disc; mesonotum with one stylus on each side of scutellum; metanotum with one pair of styli close to midline. Abdomen: First abdominal segment with two pairs of styli, one close to midline and one lateral; segments two to seven with six pairs, one pair close to midline and two other pairs lateral; segment eight with two pairs of styli; segment nine lacking styli, but with a pair of long cerci.

Number of species and distribution: Small genus, only six known species in the Nearctic and Palaearctic Regions. Two species present in western North America, A. scabrosus and A. latus. The immatures (larvae and pupae) of A. scabrosus were described by Spangler (1962), they are also briefly mentioned by Richmond (1920).

Bionomics: Like Sperchopsis, this genus lives in running waters. The specimens described by Spangler (1962) were collected from the debris in a Montana stream; Smetana (1988) also mentions that these beetles can be found in running waters of creeks and small mountain rivers; in moss or plant debris at the margins, and also under rocks or pieces of wood under waterfalls. No details on larval biology are known.

64 3- Anticura Spangler (Figures 20-22)

Egg case: Unknown

Larva: Head capsule: Subquadrangular; labroclypeus slightly asymmetrical; nasale with two prominent teeth, left one shorter; lateral lobes of epistome well developed, shorter than nasale. Frontal sulci converging towards occipital foramen, coming together near base of head; coronal sulcus very short. Six stemmata on each side of head. Gular sclerite absent, cervical sclerites present, rectangular.

Antennae: Three-segmented; basal segment as long as other two combined. Second segment carrying a short apical sensory appendage, third segment small, conical.

Mandibles: Symmetrical, with two inner teeth on basal half, distal one slightly larger.

Maxillae: Five-segmented. Stipes wide, longer than other segments combined, with a row of 13 setae on inner margin. Palpifer short, subquadrate, carrying a short apical galea. Palpi three-segmented, second segment the longest.

Labium: Formed by submentum, mentum, and prementum. Submentum subrhomboidal; mentum large, subquadrate, with strong spines on dorsal surface; prementum narrower than mentum. Palpi two-segmented, basal segment shorter; ligula present, as long as second palpal segment.

65 Thorax and legs: Pronotum covered by a large sclerite, with sagittal line; mesonotum with two pairs of subtriangular sclerites, anterior one very narrow, posterior one larger; metanotum with two narrow pairs of tergites. Prostemal plate large, subrectangular, without sagittal line. Legs five-segmented, visible in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in shape and size, with four transverse folds; folds one and four with a transverse row of four setose tubercles. Epipleurites and hypopleurites prominently lobed. Segment eight forming the spiracular atrium, with two dorsal sclerites. Segment nine reduced, trilobed, carrying pair of small one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With two supraorbital styli, and one or two pairs of short setae near midline of vertex. Thorax: Pronotum with 22 long styli, 20 on margins of pronotum, and two on disc; mesonotum with one stylus on each side of scutellum; metanotum with one stylus on each side of midline. Abdomen: First segment with four styli; segments two to seven with eight styli on posterior margin, six tergal and two pleural; segment eight with only two posterior styli; segment nine with a pair of long cerci.

66 Number of species and distribution: Monotypic genus, the only known species, A. flinty, is southern Neotropical in distribution (Argentina and Chile). The immature stages (larva and pupa) have been described by Spangler (1979).

Bionomics: This is another species that inhabits running waters. The habitat and behavior of adults and larvae of this species are described in detail by Spangler (1979). Most of the specimens collected by Spangler came from logjams at the margins of streams and small rivers. These logjams were formed by logs, sticks, leaves and other kind of compacted debris. The larvae found on these habitats moved slowly, looking for prey; adults seemed to prefer crevices or cracks in the logs, where they are more protected from the current; they do not swim.

Additional comments: Spangler (1979) points out that adults of A. flinti present wing dimorphism. He collected specimens with both normal and reduced wings, making this one of the few hydrophilids that shows this character. The percentage of winged individuals seems to be low, between 10% and 15%, both males and females have wing dimorphism.

4- Berosus Leach (Figures 23-26)

Egg case: Suboval in shape, usually flat, variable regarding presence and size of mast. Laid on a submerged substrate such as plants, sticks, etc. Egg cases with short masts have those attached to the substrate; long masts are free; a few species do not spin masts. Number of eggs varying among species (from one to 25).

67 Larva: Head capsule: Subquadrate to subtrapezoidal; labroclypeus strongly asymmetrical; nasale short, sometimes barely projecting (B. hoplites), with several short teeth. Lateral lobes of epistome also asymmetrical, right one not projecting, almost straight; left one strongly projected anteriorly, covering basal third of mandible, with several strong and short curved spines. Frontal sulci lyriform, never coming together; missing on third instar larvae; no coronal sulcus. Six stemmata on each side of head. Gular sclerite absent; no cervical sclerites.

Antennae: Three-segmented; basal segment as long or longer than other two combined, carrying a stout subapical seta on inner margin. Second segment carrying a distal sensory appendage, slightly shorter than third antennal segment.

Mandibles: Slender, strongly asymmetrical, different in shape and number of inner teeth. Right mandible with one to three inner teeth, depending on the species; distal inner margin may be serrated or not. Left mandible with three basal teeth, distal one trifid or tetrafurcated; above distal tooth a group of stout comb-like setae is present; distal inner margin of mandible serrated or not.

Maxillae: Five-segmented. Cardo small, suboval. Stipes longer than remaining segments combined, with four or five setae on inner margin; palpifer short and wide, carrying an apical galea. Palp three-segmented; basal segment very short; second segment long; third segment short and conical.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subtriangular; mentum narrower, poorly sclerotized; prementum small and narrow,

68 subquadrate. Labial palps long, two-segmented, basal segment shorter than distal; ligula reduced, as a small lobe between palpi.

Thorax and legs: Pronotum strongly sclerotized, with sagittal line. Mesosternum with two pairs of subtriangular sclerites, inner pair very small. Metasternum lacking sclerites. Prosternum with a large subrectangular plate, with sagittal line. Mesothorax and metathorax with a pair of lateral tubercles bearing a log apical seta. Legs five- segmented, long, visible in dorsal view.

Abdomen: Ten-segmented, with segment nine very small, and ten almost not differentiated. Abdominal segments one to seven subdivided by a transverse fold; some of these segments with a pair of lateral tracheal gills (usually seven pairs, but B. pugnax has only four). Segment eight small, with a subcircular tergite; spiracular atrium absent. Urogomphi reduced.

Spiracles: Nine pairs of non-functional spiracles, one mesothoracic and eight abdominal.

Pupa: Head:With or without supraorbital styli, when these are present only two pairs. Thorax: Pronotum with 24 styli, 20 on the margins and four on disc; mesonotum with one stylus on each side of scutellum; metanotum with one stylus on each side of midline. Abdomen: Abdominal segment one with one or three pairs of styli; segments two to seven with two or three pairs; segment eight with one or two pairs; segment nine with a pair of cerci.

69 Number of species and distribution: Berosus is one of the most species-rich and abundant genera within the hydrophilids. It has over 200 species worldwide. In the New World there are about 130 species, with some 80 species in South America alone (Oliva 1989, 1993). The number of species with described immatures is small, and all except one are from North America. Richmond (1920) describes B. peregrinus, and provides notes on B. striatus; Wilson (1923b) describes)?, striatus, B. pantherinus, and B. peregrinus', Archangelsky (1994b) describes all the stages of B. corrini, B. pugnax, and B. hoplites. E. Van Tassell (1966) mentions having reared or associated some 14 species, but those descriptions have not been published. Finally, Spangler (1966) described the larva of an undetermined Berosus from Peru (near Iquitos).

Bionomics: A detailed description of the general biology of Berosus is given by Van Tassell (1966); Richmond (1920), Wilson (1923), Bpving & Henriksen (1938) and Archangelsky (1994) can also be consulted. Berosus species are ubiquitous, and can be found in a variety of situations, both lotic and lentic. Adults are very active swimmers, feeding mainly on algae and other plant materials. The egg cases are laid submerged, the size and shape varying among species; the number of eggs also varies among species, but is more or less constant within each species. Females can lay several egg cases during each mating season. Larvae are benthic, predaceous, feeding on other small invertebrates; most species are also cannibalistic. Berosus larvae are apneustic, and are the only ones within the Hydrophilidae to possess tracheal gill. Pupation occurs in the soil or sand near the waters edge, one to five inches below the surface. Aouad (1988) describes the life cycle of a Moroccan Berosus, pointing out that they are univoltine in temporary habitats, but bivoltine in permanent environments.

70 Additional comments: Regarding the adult stage, Berosus species have been the subject of audiospectographic studies. Van Tassell, (1965) studied 12 North American species, and sympatric species displayed comparatively different chirps, making them easy to distinguish. The greatest variation was in the premating chirps, suggesting an isolating mechanism; on the other hand stress chirps showed less variation. Regarding immature stages of Berosus, there seems to be a lot of variation in larval and pupal morphology, especially the number of styli in the pupae, and the number of tracheal gills in the larvae. Bertrand (1972), based on undetermined larvae, recognized five different genera which he named “Berosini genera 1-5”; the main difference of those larvae was the number of tracheal gills on the abdomen (ranging from two pairs to 16 pairs, even some with odd numbers such as five or nine gills). Among pupae the differences are in the number of cephalic and abdominal styli, something that in other known hydrophilid genera seems to be a stable condition.

5- Derallus Sharp (Figures 27-29)

Egg case: Attached to floating vegetation, always submerged. Round and flat, made of two silk layers; first attached to the substrate, second over the eggs, thicker and light brown in color. Mast absent. Four to six eggs in each case.

Larva: Head capsule: Subquadrangular; labroclypeus symmetrical; nasale short, with several short teeth on anterior border of epistome; lateral lobes of epistome rounded, short, projecting as far as nasale. Frontoantennal sulci reaching occipital foramen, never

71 fusing; coronal sulcus absent. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, subrectangular.

Antennae: Three-segmented; basal segment slender, longer than other two combined, with a subapical inner process carrying a seta. Second segment bearing a long sensory appendage, slightly shorter than third antennal segment.

Mandibles: Symmetrical, long and slender, with two inner teeth on basal half; distal tooth large, basal one small. Preapical inner margin serrated ( D. angustus) or not (D. rudis).

Maxillae: Five segmented. Cardo small, subtriangular; stipes slender and longer than remaining segments combined, with four or five setae on inner margin; palpifer short, carrying an apical galea. Palpi three-segmented, basal segment very short, second segment the longest, third segment also short.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subpentagonal; mentum large, subquadrate, as wide as submentum, dorsal surface with strong spines on the middle; prementum long and narrower than mentum, subrectangular, longer than wide. Palpi two-segmented, basal segment short; ligula present, about three times as long as basal segment of palpus.

Thorax and legs: Prothorax broader than head; pronotum strongly sclerotized, with surface covered by minute spines, with sagittal line and a fringe of long, slender setae around the margins. Mesothorax with two pairs of subtriangular tergites; metathorax with only one pair of irregular tergites. Prosternum large, subrectangular, without

72 sagittal line. Both mesothorax and metathorax with five pairs of setiferous projections. Legs five-segmented, long, visible in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven with five pairs of setiferous projections, three on the sides, and two closer to midline. Eighth segment without projections, covered by a semispherical tergite, covering the spiracular atrium. Segment nine trilobed, with a pair of small unsegmented urogomphi on membrane between segments eight and nine.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With two pairs of supraorbital styli, upper one larger. Thorax: Pronotum with 24 styli, twenty on the margins, and four on disc; mesothorax with one stylus on each side of scutellum; metathorax also with one pair. Abdomen: Segments one to seven with three pairs of styli, outer one short and arising from dorsal surface of flat pleural lobes, inner two pairs long and slender. Eighth abdominal segment also with flat pleural lobes, each with a short stylus; segment nine carrying a pair of short cerci.

Number of species and distribution: Small genus with only 14 describe species (Oliva 1983); Neotropical and southern Nearctic in distribution, most of the species are from South America. Spangler (1966) described the larva of D. rudis, Archangelsky & Durand (1992b) described all the stages of D. angustus.

73 Bionomics: Adults and larvae are found among the aquatic vegetation in ponds, ditches, and slow flowing streams or rivers. Adults are fairly good swimmers, and feed on algae and decaying plant material. Larvae stay on the vegetation, where they crawl looking for prey, they are also cannibalistic. The long setiferous projections that cover their body soon become covered by algae and dirt, making them difficult to find (crypsis). Pupation occurs on the aquatic vegetation, completely exposed. Pupae obtained from specimens reared in natural conditions have a cryptic coloration (green) and also have a short duration (two days). The egg cases are laid submerged and contain four to six eggs.

Additional comments: Derallus has been typically included within the tribe Berosini, due mainly to adult characters, but there has been disagreement by some authors regarding the placement of these beetles. Young (1954), Bertrand (1962, 1972), and Spangler (1966) point out that Derallus should be transferred to its own tribe, together with Regimbartia and Allocotocerus; larval morphology seems to support this point of view, although Hansen (1991) kept them within the Berosini based mainly on adult morphology.

6- Chaetarthria Stephens (Figures 30-31)

Egg case: Unknown.

74 Larva: Head capsule: Subquadrate; labroclypeus symmetrical; nasale projecting, almost triangular, with a long median tooth and two short lateral teeth; lobes of epistome large, rounded, slightly shorter than nasale. Frontoantennal sulci converging towards occipital foramen, without coming together; coronal sulcus absent. Six stemmata on each side of head, closely aggregated. Gular sclerite absent; cervical sclerites small, suboval, narrow, difficult to see.

Antennae: Three-segmented, short; segments one and two of the same length, third segment shorter.. Apical sensory appendage of second segment slightly longer than third segment.

Mandibles: Symmetrical, strongly curved; with two inner teeth at midlength, both teeth similar in size.

Maxillae: Five-segmented, cardo small, irregularly shaped. Stipes wide and longer than remaining segments combined, with several small spines on dorsal surface; palpifer shorter and broad, carrying an apical galea. Palp three-segmented, slightly longer than palpifer; first segment short and broad; second segment about the same length; third segment narrower, slightly longer.

Labium: Formed by submentum, mentum, and prementum. Submentum wide and short; mentum long, narrow in the middle; prementum subtrapezoidal, as long as mentum, closely attached to mentum. Palpi two-segmented, first segment shorter than second; ligula present, as long as palpi, round.

75 Thorax and legs: Prothorax covered by a large dorsal plate, with sagittal line; mesothorax with two pairs of narrow transverse tergites; metathorax with one pair of narrow plates. Prostemum with a subrectangular plate. Legs reduced, without claw; other segments very short; nor visible in dorsal view.

Abdomen: Ten-segmented; segments nine and ten reduced. Segments one to seven similar in size and shape, broad and with two or three transverse folds, each segment with a pair of anterior tergites, becoming smaller towards the posterior end. Abdominal segment eight with a subdivided dorsal shield. Segment nine trilobed, carrying a pair of short one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, small but functional, within the spiracular atrium.

Pupa: Unknown.

Number of species and distribution: Rather small genus, worldwide in distribution, with about 45 described species, of which almost 40 are from the New World. Bpving & Henriksen (1938) and Hrbdcek (1943) describe the larva and biology of the European Ch. seminulum. This is the first description of a New World Chaetarthria.

Bionomics: Not much is known about species of this genus; adult Chaetarthria are semiaquatic, burrowing in sand at the margins of creeks or rivers, usually where the waters are quiet. According to Miller (1974) these beetles seem to be nocturnal, staying in their burrows during the day. As other members of the tribe Chaetarthriini, these

76 beetles have a concavity on each side of the first abdominal stemite, filled with a hyaline substance, a globulin protein (Miller 1974), whose function is unknown. Larvae reared in laboratory did not show any adaptation for swimming, they are quite sluggish in movements, so they do not seem to be aquatic, they rather crawl in the sandy margins, and feed on other small invertebrates; some reports mention adults of the European Ch. seminulum as occurring in the water itself (Miller 1974).

7- Guyanobius Spangler (Figures 32-33)

Egg case: Unknown.

Larva: Head capsule: Subquadrate; labroclypeus symmetrical; nasale prominent, formed by five strong teeth; lateral lobes of epistome slightly shorter than nasale, subtriangular. Frontal sulci converging towards occipital foramen, not fusing; coronal sulcus absent. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites narrow, transverse and subtriangular.

Antennae: Three-segmented, basal segment wide, as long as second segment; second segment carrying a distal sensory appendage as long as third antennal segment.

Mandibles: Symmetrical, with three inner teeth; distal two inner teeth larger than basal one.

77 Maxillae: Five-segmented. Cardo small; stipes longer and wider than remaining segments, with a row of three or four strong setae on inner margin. Palpifer subquadrate, carrying an apical galea. Palpi three-segmented; basal two segments short, subequal in length; third segment slightly longer than other two.

Labium: Formed by submentum, mentum, and prementum. Submentum wide, subpentagonal; mentum subrectangular, longer than wide, with dorsal surface covered by cuticular spines; prementum subquadrate, without spines. Palpi three-segmented, basal segment very short, distal segment as long as mentum; ligula longer than palpi, subtriangular.

Thorax and legs: Prothorax covered by a large dorsal plate, sagittal line present; sternal sclerite large, subrectangular, with sagittal line. Mesothorax with two subrectangular tergites. Metathorax with two pairs of narrow tergites, posterior ones smaller. Legs five-segmented, well developed, visible in dorsal view.

Abdomen: Ten-segmented; segments nine and ten reduced. Segments one to seven similar in shape and size, subdivided by a transverse fold; each segment with a pair of small oval tergites; pleural areas strongly lobed. Segment eight with small lateral lobes, covered by a large dorsal plate; ninth segment smaller, trilobed, with a pair of small one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

78 Pupa: Unknown.

Number of species and distribution: Small genus, with only two Neotropical species: G. adocetus Spangler, from Guyana and G. simmonsorum Spangler, from Brasil. The larva of G. adocetus was described by Spangler (1986).

Bionomics: Little is known about this genus. According to Spangler (1986) adults and larvae of G. adocetus were collected in leaf packs lodged against rocks and logs in the banks of a small stream within a dense rainforest. The substrate of the forest was sand, gravel, and rock. The adults of C. simmonsorum come from a similar habitat.

8- Paracymus Thomson (Figures 34-36)

Egg case: Sac-shaped, made of two thin layers of silk, with a short and wide mast. Four to six eggs in each case. The egg cases are laid among filamentose algae that grow on the water’s surface.

Larva: Head capsule: Subquadrate, slightly wider than long; labroclypeus asymmetrical; nasale formed by four strong teeth; lateral lobes of epistome rounded, projecting as far as nasale. Frontal sulci lyriform, reaching occipital foramen widely apart; coronal sulcus absent. Six stemmata on each side of head. Cervical sclerites small, oval; gular sclerite absent.

79 Antennae: Three-segmented; first segment wider and slightly longer than second; sensory appendage on second segment as long as third segment.

Mandibles: Symmetrical, with three inner teeth at midlength, distal two large, basal one much smaller; distal inner margin of mandible and inner margin of distal tooth finely serrated; no molar area.

Maxillae: Five-segmented. Cardo small, irregularly shaped; stipes wide and longer than remaining segments combined, with five stout setae and several spines on mesal margin; palpifer large, longer than palp, carrying a short and unsclerotized apical galea, also with several mesal and dorsal spines. Palp three-segmented, all segments wide and short, subequal in length.

Labium: Formed by submentum, mentum, and prementum. Submentum wide, subpentagonal; mentum subquadrate, with a few strong dorsal spines and a row of stout setae on distal margin; prementum smaller, subquadrate, with a few cuticular spines on distal half. Palpi two-segmented, basal segment short, with spines on dorsal surface. Ligula present, slightly shorter than palpi.

Thorax and legs: Pronotum strongly sclerotized, with sagittal line; prosternal plate subrectangular, divided by a wide sagittal line. Mesothorax with two pairs of tergites, anterior one small, subtriangular, posterior one larger; metathorax with two pairs of small, suboval tergites. Legs five-segmented, well developed but short, not visible in dorsal view.

80 Abdomen: Ten-segmented; segments nine and ten reduced. Segments one slightly shorter than remaining ones, with three transverse rows of small oval tergites. Segments two to seven similar in size and shape, subdivided by transverse folds, each segment with four rows of small oval tergites; pleural areas lobed. Segment eight with two small anterior tergites and a posterior large dorsal plate. Segment nine trilobed, with a pair of small one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: with two pairs of supraorbital styli. Thorax: Pronotum with 24 styli; 20 on the margins, and four on disc. Mesonotum with one stylus on each side of scutellum; metanotum also with one pair near base of wingpads. Abdomen: Abdominal segments one to seven with a transverse row of six dorsal styli; pleurites two to seven each with one stylus. Segment eight with one pair of dorsal styli; segment nine carrying a pair of cerci.

Number of species and distribution: Fairly large genus, with over 70 species, worldwide in distribution, with about 40 species in the New World.

Bionomics: Paracymus species are semiaquatic, and can be found at the water’s edge, usually in ponds or by quiet streams or rivers. Adults lay eggs among the algae or vegetation at the edges. Larvae hatch after four to six days, and live in the same habitat

81 as adults do, feeding on other small invertebrates; larval development takes between 30 and 40 days. Pupation takes place in small cells dug in the soil near the water’s edge, close to the surface.

Additional comments: The larvae described and illustrated by Richmond (1920) as Paracymus subcupreus show several differences with the ones reared and described here. In first place the larvae described here have three inner teeth on the mandible (two the one described by Richmond); the number of teeth on the labroclypeus is also different, four in the larvae reared by me, and five in that described by Richmond. There are also some important differences in the structure of the labium, the most striking being a subdivided ligulain Richmond’s description, contrasting with a simple ligula in my description. All these characters, and also the number and shape of the abdominal tergites, suggest that the larva described by Richmond was wrongly associated, or that the adults were misidentified by him. Richmond’s description seems to be closer to that of a Crenitis larva than to one of Paracymus.

9- Crenitis Bedel (Figures 37-39)

Egg case: Unknown.

Larva: Head capsule: Subquadrate; labroclypeus asymmetrical, nasale obliquely truncate, right side longer than left, with five prominent teeth; lateral lobes of epistome rounded, shorter than nasale, each with four stout setae projecting mediad. Frontal sulci parallel at distal end, slightly diverging at basal third, then coming together near occipital foramen,

82 never fusing; coronal sulcus absent. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites small and narrow, difficult to see.

Antennae: Three-segmented, long. First segment the longest, shorter than next two combined, with an inner row of strong cuticular spines; second segment slightly shorter than first, also with a row of inner spines, carrying a slender and long sensory appendage, as long as last antennal segment; third segment the shortest, without spines.

Mandibles: Symmetrical, with three inner teeth; distal tooth the largest, basal one the smallest, as a small rounded lobe. Distal inner margin of mandible slightly serrated.

Maxillae: Five-segmented; cardo subdivided, irregularly shaped. Stipes short, wider than other segments, inner margin convex, with a row of 5 stout setae, inner and dorsoapical margins with numerous cuticular spines; palpifer long, slightly shorter than stipes, with a short apical galea and several inner and dorsal cuticular spines. Palpi three-segmented, the three segments subequal in length.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subpentagonal; mentum subtrapezoidal, narrowing towards anterior end, apicolateral angles with several long and stout setae, dorsal surface covered by a fine pubescence at the base, and cuticular spines on middle and distal areas; prementum smaller, subpentagonal. Palpi two-segmented, first segment short, half the length of second or less, second segment with cuticular spines on dorsal surface; ligula present, as long as palpal segments, with a small constriction at midlength.

83 Thorax and legs: Pronotal shield large, subdivided by a sagittal line, with a fringe of long hairs on anterior margin, laterally extending almost to sternal plate, dorsally with a large subquadrate lobe on each side; prostemal plate large, subrectangular, with sagittal line. Mesonotum with a large subrectangular plate, with sagittal line; metanotum with two narrower plates, with sagittal line; meso- and metanota with one pair of lateral finger-like projections; pleural areas lobed. Legs five-segmented, short but well developed, difficult to see in dorsal view.

Abdomen: Ten-segmented; segments nine and ten reduced. Segments one to seven similar in shape and size, each with two pairs of small dorsal plates (one anterior, one posterior), separated by a sagittal line, posterior plates with a long finger-like projection; each segment with one pair of long, lateral finger-like projections like those of meso- and metathorax; pleurites one to seven lobed. Segment eight smaller, with a subquadrate dorsal plate; posterior margin with three slender projections, middle one with tip slightly bifid; segment nine trilobed, without projections, carrying a pair of small one-segmented urogomphi.

Pupa: Head: With two supraorbital styli. Thorax: Pronotum with 24 styli, 20 on margins, four on disc. Mesonotum with one stylus on each side of scutellum; metanotum with one pair of styli near midline. Abdomen: Segments one to seven with a transverse row of four dorsal styli; pleurites two to seven each with one stylus. Segment eight with one pair of styli on posterior angles; segment nine carrying a pair of cerci.

84 Number of species and distribution: Crenitis has 38 described species world wide (Hebauer 1994). It is present in all the major biogeographical regions, except for the Australian. The larva of the Palaearctic C. punctatostriata has been described by van Emden (1932); the pupa of the same species was described by Matthey (1977). This is the first description of a New World Crenitis larva.

Bionomics: Matthey (1976) studied the distribution and ecology of C. punctatostriata. Both adults and larvae are aquatic or semiaquatic, living in peat bogs; other New World species are found at margins of creeks, on rocks, moss, or among leaf debris; a few New World species seem to prefer standing waters such as ponds or marshes, with plenty of moss or debris on the margins. Larvae are not capable of swimming, being restricted to crawling on the substrate. Egg cases are unknown for this genus, as well as the larval diet, but from the mandibular morphology, they seem to be predatory, as most other hydrophiloids.

10- Anacaena Thomson (Figures 40-41)

Egg case: Small, bag-shaped; mast very long, narrow and flat (about five times the length of the egg case). Five to eight eggs in each case.

Larva: Head capsule: Subquadrate; labroclypeus asymmetrical; nasale with four small teeth; lateral lobes of epistome rounded, slightly asymmetrical. Frontal sulci U-shaped, coming together at the occipital foramen; coronal sulcus absent. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, small.

85 Antennae: Short, three-segmented; first segment the longest; segment two carrying an apical sensory appendage as long as last segment; third segment short, conical.

Mandibles: Symmetrical, sharply pointed; with three inner teeth at midlength, basal one smaller. No molar area.

Maxillae: Five-segmented. Stipes wide, as long or longer than remaining segments combined, with five strong setae on inner margin; palpifer subrectangular, as long as palp, carrying a small apical galea. Palp three-segmented, first and second segments wider than long (first instar larvae), distal segment the longest.

Labium: Formed by submentum, mentum, and prementum. Submentum small; mentum longer than broad, with cuticular spines on dorsal surface; prementum subquadrate, lacking spines. Palpi two-segmented, distal segment two to three times longer than basal one (first instar larvae). Ligula present, as long as distal palpal segment.

Thorax and legs: Pronotum covering completely dorsal side of prothorax, with sagittal line; anterior margin with a fringe of short setae. Mesothorax with two pairs of subtriangular dorsal sclerites, posterior ones larger; metathorax also with two pairs of small dorsal sclerites, anterior ones larger, suboval. Legs five-segmented, well developed but short, not or barely visible in dorsal view (Richmond 1920, Winterboum 1971).

86 Abdomen: Ten-segmented; segments nine and ten reduced. Segments one to seven similar in shape and size; subdivided by transverse folds, each bearing a row of small tubercles; pleural area conspicuously lobed. Segment eight with a large dorsal, subrectangular shield. Segment nine slightly trilobed, carrying a pair of small one- segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Unknown.

Number of species and distribution: The genus Anacaena is world wide in distribution, with about 52 described species. The egg case and larva of the Nearctic species A. infuscata was described by Richmond (1920).

Bionomics: Adults are semiaquatic, being common among the grass or plant debris at the margins of ponds or streams. Springs seems to be the breeding season for species in temperate regions (Richmond 1920); eggs are laid on debris at the waters margin, and larvae hatch after eight or ten days. Larval development is slow, about two months (Richmond 1920); larvae wander on the waters edge, on moist soil and among the debris, looking for prey. Pupae were observed by Richmond (1920) but never described. Adults and third instar larvae can overwinter. Larvae of a New Zealand species, A. tepida, were described by Winterboum (1971); they were collected in association with adults, living in the effluent channel of a hot spring (38°C at the collection site, pH was 9.20).

87 Additional comments: D’Orchymont (1913) described a larva he assigned to the European species A. limbata. According to other authors, and based on Richmond’s description of Paracymus subcupreus, this larva was assigned to the genus Paracymus, probably P. aeneus (Richmond 1920; Bpving & Henriksen 1938). As I mentioned above (see additional comments on Paracymus) Richmond’s description of P. subcupreus does not agree with mine, and the larva he described does not seem to belong to the genus Paracymus. On the other hand, the larva illustrated by d’Orchymont looks similar to the one described by Richmond, suggesting that both could belong to the same genus (either Crenitis or Anacaena).

11- Notionotus Spangler (Figures 42-43)

Larva: Head capsule: Subquadrate; labroclypeus asymmetrical; nasale broad, obliquely truncate, right side longer than left, with eight irregular teeth, some of them notched at apex; lateral lobes of epistome rounded, poorly developed, much shorter than nasale. Frontal sulci inversely bell-shaped, coming together before reaching occipital foramen; coronal sulcus present, very short. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, wide and narrow, poorly sclerotized and difficult to see.

Antennae: Three-segmented, short. First segment slightly wider than second, slightly shorter than second segment; third segment the shortest, slightly longer than sensory appendage of second segment.

88 Mandibles: Asymmetrical, each with two inner teeth and with distal margin serrated. Right mandible with distal inner tooth large, bifid, serrated along inner margin; basal tooth smaller, pointing backwards. Left mandible with distal tooth broadly bifid, slightly serrated alonf inner margin; basal tooth very small.

Maxillae: Five-segmented; cardo small, subtriangular. Stipes wide and longer than remaining segments combined, inner margin slightly convex basally and with five strong setae; palpifer short, subrectangular, shorter than wide, carrying an apical galea as long as first palpal segment. Palpi three-segmented, first segment the shortest, second and third segments subequal in length, each twice as long as first segment.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subpentagonal; mentum subquadrate, with a large triangular area of strong cuticular spines at base; prementum subtrapezoidal, wider basally. Palpi two-segmented, second segment twice as long as first, intersegmental membranes between prementum and first palpal segment and between palpal segments with long, flat spines; ligula present, slightly shorter than basal segment of palpus.

Thorax and legs: Pronotal shield large, covering most of pronotum, poorly sclerotized (1st instar), with sagittal line; prostemal plate large, subrectangular, without sagittal line. Mesonotum with a subtrapezoidal plate, wider anteriorly, divided by a sagittal line; metanotum with two small plates. Legs five-segmented, short but well developed, visible in dorsal view.

89 Abdomen: Ten-segmented; segments nine and ten reduced. Segments one to seven similar in shape and size; subdivided by transverse folds, lacking plates or tubercles. Segment eight with a large dorsal, subquadrate shield. Segment nine slightly trilobed, carrying a pair of small one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Unknown.

Number of species and distribution: This is a small genus, with only five described species (Perkins, 1979), all from the Neotropical region. This is the first description of larvae of this genus.

Bionomics: Very little is known about these beetles. Adults are found in two different habitats. The first is hygropetric (Spangler 1972), living on the wet surfaces of rock walls that margin small montane streams, usually found in cracks or among the leaflitter collected there; the other habitat is among rocks and plant debris trapped on the margins of small creeks (Perkins 1979). Adults feed on the algae and decaying plant material in those habitats; larvae are predatory, feeding on other small invertebrates. The species described here, N. liparus, was collected on steep rock walls along a montane creek in the Venezuelan cloud forest (National Park Henri Pittier); the adults were found among the moss and leaflitter gathered on cracks, the walls where these specimens were collected were always extremely wet, but not necessarily close to the water.

90 12- Laccobius Erichson (Figures 44-46)

Egg case: Attached to rocks or vegetation at the water’s edge. Almost spherical, covered by sand grains, with a long, filamentous mast five to six times the length of the egg case. The number of eggs varies from two to more than ten.

Larva: Head capsule: Subquadrate; labroclypeus strongly asymmetrical; nasale prominent, with three to five teeth; lateral lobes of epistome asymmetrical, rounded, both projecting farther than nasale; left one the largest, covering basal third of mandible, with a row of strong curved setae on mesal margin; right lobe smaller, covering basal quarter of mandible, without strong setae. Frontal sulci parallel, reaching occipital foramen without coming together, difficult to see in third instar larvae; coronal sulcus absent. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, small and oval, difficult to see in first instar larvae.

Antennae: Three-segmented. Second segment the longest, carrying an outer sensory appendage about the same length of third segment; first segment half the length (first instar larvae) to slightly shorter (third instar larvae) than second segment.

Mandibles: Strongly asymmetrical; left mandible with two or three inner teeth at midlength (third when present very small), second tooth and base of mandible with several strong spines projecting mediad; right mandible with two inner teeth, larger than those of left mandible, distal inner margin slightly serrated. No molar area.

91 Maxillae: Five-segmented, cardo small, subdivided. Stipes wide, longer than remaining segments combined, inner margin with five strong setae and several small spines; palpifer small, subquadrate, incompletely sclerotized, carrying a small apical galea. Palpi three-segmented, first segment the shortest, second and third segments subequal in length.

Labium: Formed by submentum, mentum and prementum. Submentum small and narrow, subtrapezoidal; mentum also small and narrow, subrectangular; prementum slightly larger, trapezoidal. Palpi two-segmented, first segment shorter, second segment two to three times longer than first. Ligula reduced.

Thorax and legs: Prothorax completely covered by a large dorsal plate, with sagittal line; tergum with a large subrectangular plate, with sagittal line. Mesothorax with two pairs of dorsal sclerites, anterior one small, oval; posterior pair larger, subtriangular. Metathorax with only one pair of subtriangular sclerites. Legs five-segmented, well developed, visible in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in shape, tapering towards posterior end, segments subdivided by transverse folds; segments one to seven with a pair of small oval plates on anterior fold, close to midline; median fold with a transverse row of four tubercles; pleural areas lobed. Segment eight with a subcircular plate. Segment nine trilobed, carrying a pair of small one-segmented urogomphi.

92 Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With two pairs of well developed supraorbital styli. Thorax: Pronotum with 22 styli and a pair of small pointed cones (reduced styli); 18 styli and the pair of cones along the margins, remaining two pairs on disc. Mesonotum and metanotum each with one pair of styli near the midline. Abdomen: Segments one to seven with a row of four styli on the terga, segments two to seven with one stylus on each pleura. Eighth segment with only four reduced styli, appearing as small conical outgrows. Ninth segment with a pair of long cerci.

Number of species and distribution: Laccobius is a large genus with close to 200 species. It is present in all the major biogeographical areas with the exception of the Neotropical region. There are 28 described species (Cheary 1971) in the Nearctic region, of which only the immature stags of L agilis have been described in detail (Richmond 1920); Wilson (1923b) describes the pupa of L. agilis. Cheary (1971) in his revision gives a generic description of the larva and pupa, illustrates the larva of L. bruesi, and the head capsules of L. carri carri, L. ellipticus, and L. borealis; he also shows photographs of the egg case of L. ellipticus and the larva of L. bruesi; several more drawings and photographs accompany the description of the construction of the egg case and larval feeding.

Bionomics: A detailed account on the life history of Laccobius is provided by Cheary (1971). Adults are aquatic, living in the littoral zone of ponds or streams; they are very

93 good swimmers, and usually stay concealed, burrowing in the mud or hiding among the vegetation. Spring seems to be the breeding season, but some species oviposit all summer long. Egg cases are constructed in the water, close to the water’s surface; the mast always protrudes above the surface. Larvae hatch after seven to 11 days, they are predaceous, feeding on other invertebrates, also cannibalistic. Larval development is slow, between 45 and 60 days. When the third instar larvae reach the prepupal stage, they leave the water and wander looking for a place where to dig the pupal chamber. Adults emerge after three to five days.

Additional comments: The genus Laccobius has changed position within the Hydrophilidae in more than one occasion. It was considered within the tribe Berosini (or subfamily Berosinae) by van Tassell (1966). D’Orchymont (1942), Cheary (1971), and Smetana (1986) considered it as part of the Hydrobiinae. More recently Hansen (1991) placed them within the tribe Oocyclini. Its interesting to mention here that the larvae of Laccobius (and Oocyclus) share several characters with the larvae ofBerosus", some of these are the shape of the asymmetrical labroclypeus, the shape of the mandibles and also the labium, with a reduced ligula. There are also several characters that are very different, such as the presence of cervical sclerites and a spiracular atrium in Laccobius and Oocyclus (Berosus larvae lack both of them, and have tracheal gills).

13- Oocyclus Sharp (Figures 47-49)

Egg case: Bag-shaped, laid on rocks near the water, always over the waters surface. Made of two thick silk layers, first one forming the cup, second one closing the case, with a wide ribbon around the cap, irregular in width; no definite mast is present.

94 Number of eggs six to eight.

Larva: Head capsule: Subquadrate; labroclypeus strongly asymmetrical; nasale prominent, with five irregular teeth; lateral lobes of epistome strongly asymmetrical, rounded, right one projecting as far as nasale, without spines, left one projecting much farther than nasale, covering basal third of left mandible, inner margin with five stout setae projecting inwards. Frontal sulci lyriform, coming together at occipital foramen; coronal suture absent. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, narrowly oval.

Antennae: Three-segmented, short. First and second segments subequal in length and width; first segment constricted at base; second segment carrying a short apical sensory appendage, half the length of third antennal segment; third segment the shortest.

Mandibles: Strongly asymmetrical. Right mandible with three inner teeth at midlength, distal one the largest; middle tooth near distal one, smaller; third tooth near base, as a small cone; distal inner margin of mandible serrated. Left mandible with a furrow along inner margin, with three small inner teeth on basal half, all pointing backwards; between middle and basal teeth a tuft of five or six spines setae is present, base of mandible also with strong spines.

Maxillae: Five segmented; cardo small, subtriangular. Stipes wide, as long or slightly longer than remaining segments combined, with three stout setae on inner margin, and a few minute spines on basal half; palpifer subrectangular, wider than long, carrying an apical galea as long as first palpal segment. Palpi three-segmented, basal segment the

95 shortest; second segment slightly longer than third.

Labium: Formed by submentum, mentum, and prementum. Submentum wide, subtriangular; mentum subrectangular, longer than wide, dorsal surface with several cuticular spines on distal half; prementum slightly narrower than mentum, subquadrate. Palpi two-segmented, distal segment three times longer than basal one; membrane between prementum and first palpal segment, and between first and second palpal segments with several long, flat spines; ligula reduced, undistinguishable.

Thorax and legs: Pronotal shield large, covering most of pronotum, sagittal line present; prosternal plate subdivided into two subrectangular sclerites, widely separated. Mesonotum with two pairs of plates narrowly separated, anterior pair narrow, subtriangular; posterior pair large, subrectangular; metanotum with two pairs of smaller plates, widely separated, anterior pair large, suboval; posterior pair smaller, narrowly suboval. Legs five-segmented, well developed, visible in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. First abdominal segment with a pair of small oval tergites, difficult to see; segments one to seven similar in shape and size, subdivided into three transversal folds, posterior fold with a pair of small lateral tubercles; pleural areas slightly lobed. Segment eight with a large suboval tergite, posterior end notched at middle and with four small irregular lobes; segment nine trilobed, with three small dorsal plates, carrying a pair of small one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular,

96 large and functional, within the spiracular atrium.

Pupa: Unknown.

Number of species and distribution: Small genus, with ten described species from the Neotropical and Oriental regions. Five species are known from the neotropics. This is the first description of the egg case and first instar larvae of this genus.

Bionomics: Little is known about the biology of this genus. Adults and larvae live among the moss and algae that grow on rocks near montane creeks. Adults feed on the algae, moss, and debris accumulated on the rocks, and they are not always close to the water, sometimes they can be collected up to several feet away from the water, on vertical rock walls that margin these creeks (nonetheless the habitat is always very wet). Females attach their egg cases on the rocks, always above the water surface, each case containing from six to eight eggs. Larvae hatch after six to seven days, and are predaceous, also cannibalistic, preying on small invertebrates that live in the moss or algae; they do not go into the water.

14- Helochares Mulsant (Figures 50-52)

Egg case: Carried by the female, semicircular and flat, following the contour of the abdomen and slightly protruding at the caudal end. It is attached to the hind femora by a few strands of silk. Depending on the species the number of eggs ranges between 25 and 100. There is no mast.

97 Larva: Head capsule: Subquadrate; labroclypeus asymmetrical; nasale obliquely truncate, shorter on left side, with five to seven small teeth; lateral lobes of epistome may project farther than nasale or not. Frontal sulci inversely bell-shaped, meeting before reaching occipital foramen; coronal sulcus present, very short. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, narrow, subrectangular.

Antennae: Three-segmented. First segment as long as second (first instar larvae) or longer (second and third instar larvae); second segment carrying an apical sensory appendage, half the length of third segment.

Mandibles symmetrical to slightly asymmetrical; with two inner teeth at midlength, distal one larger. Distal inner margin of mandible and inner margin of basal tooth may be serrated.

Maxillae: Five-segmented, cardo small, subtriangular. Stipes wide and longer than remaining segments combined, with a row of five or six stout setae on inner margin, base of stipes with a tuft of strong spines; palpifer short, subrectangular, carrying an apical galea as long or longer than first palpal segment. Palpi three-segmented, segment one very short, second segment the longest, third segment slightly shorter than second.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subpentagonal; mentum large, subquadrate to subtrapezoidal, with dorsal surface covered by strong cuticular spines; prementum subrectangular, wider than long. Palpi two-segmented, basal segment very short, distal segment three to four times longer than basal one; ligula present, long and slender, slightly shorter than second palpal

98 segment.

Thorax and legs: Pronotum almost completely covered by a dorsal shield, with sagittal line; prosternum with a subrectangular plate, subdivided by a sagittal line. Mesothorax with a pair of large tergites; metathorax with a pair of small plates, irregular in shape. Legs five-segmented, well developed, visible in dorsal view.

Abdomen ten-segmented; segments nine and ten reduced. Segments one to even similar in size and shape, subdivided by three or four transverse folds; segment one with two pairs of small, narrow tergites; segments one to seven with four small tubercles; pleural areas slightly lobed; abdominal sternites strongly folded. Segment eight with a large, suboval tergite; segment nine trilobed, with a pair of small one- segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With two pairs of supraorbital styli, which can be minute (H. talarum). Thorax: Pronotum with 22 or 24 styli, 18 or 20 along the margins, and a transverse row of four on disc. Mesonotum with one stylus on each side of scutellum; metanotum with one pair near midline. Abdomen: Tergites one to seven with a transverse row of four or six styli; segments two to seven with one stylus on each pleurite. Eight segment with two styli, missing in some species; segment nine carrying a pair of cerci.

99 Number of species and distribution: Helochares is a large genus, with about 130 species described. Worldwide in distribution, more common in the tropical and subtropical regions. About 30 species are known from the New World. Richmond (1920) described the immature stages of H. macullicollis, and Fernandez (1983) described those of H. talarum and H. pallipes. Ferndndez (1990) and Fernandez & Kehr (1994,1995) provide information on the populational ecology of H. talarum and H. femoratus.

Bionomics: Detailed information on the biology of this genus can be obtained in the papers mentioned above. Adults are aquatic, living in the littoral zone, close to the water’s edge, or associated to the floating vegetation. They prefer quiet bodies of water. The egg cases are carried by the female; egg development is about a week, and after the eggs hatch, the female gets rid of the empty case. Larvae are predatory, also cannibalistic. Development of the larval instars varies among the different species, but it is at least two months. Pupation takes place in the soil, near the water; pupal development is about a week. A study by Ferndndez & Kehr (1994) concluded that populations of H. femoratus are multivoltine in the area of study, but could show variation depending on the latitude. On the other hand western European species (Cuppen 1986) are univoltine; Cuppen also mentions that a small proportion of these European species overwinter as larvae or pupae.

Additional comments: Hansen (1991) mentions the heterogeneity of the genus Helochares; his remarks are based on the adult morphology. Comparison of descriptions of larvae and pupae from different biogeographical regions (Nearctic: Richmond 1920; Palaearctic: d’Orchymont 1913 and Bpving & Henriksen 1938;

100 Australasian: Anderson 1976) support Hansen’s conclusions.

15- Helobata Bergroth (Figures 53-54)

Egg case: Carried by female on underside of abdomen; dorsal surface clear, shiny; ventral surface opaque, coated with debris. Attached to hind femora by two strands of fibers. No mast. Number of egg 30 to 35.

Larva: Head capsule: Subquadrate; labroclypeus symmetrical; nasale absent, replaced by a deep median emargination; lateral lobes of epistome large, rounded. Frontal sulci as an inverted bell, reaching occipital foramen without fusing; coronal sulcus absent. Six stemmata on each side of head. Gular sclerite absent; no cervical sclerites in dorsal view.

Antennae: Three-segmented; first segment about two thirds the length of second; second segment the longest, as wide as first segment, carrying an apical sensory appendage slightly shorter than third antennal segment.

Mandibles: Symmetrical, sharply pointed; inner margin with two teeth, distal one larger. Distal inner margin and inner margin between two inner teeth strongly serrated.

Maxillae: Stipes large, swollen at midlength, slightly shorter than remaining segments combined, with a row of nine short and strong setae on inner margin; palpifer subrectangular, wider than long, carrying a short apical galea. Palpi three-segmented,

101 basal segment the shortest, distal segment the longest.

Labium: Mentum subquadrate, slightly wider than prementum; prementum subrectangular, longer than wide. Palpi two-segmented, second segment slightly longer than first; ligula present, very short.

Thorax and legs: Pronotum subrectangular, wider than long; mesonotum and metanotum slightly wider but narrower than pronotum. No reference to the legs in the original description (Spangler & Cross 1972).

Abdomen: Ten-segmented; segments nine and ten reduced. Segments one to seven similar in shape, narrowing towards caudal end; subdivided by a transverse fold; each segment with one lateral tubercle on each side, bearing a long seta, and a transverse row of four small tubercles on tergal surface. Segment eight with a large suboval plate with four lobes on caudal margin. Segment nine trilobed, carrying a pair of small one- segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Unknown.

Number of species and distribution: Helobata is a small genus, with only six described species, all of them in the New World. All of the species are Neotropical in distribution (Ferndndez & Bachmann 1985), and only one species, H larvalis (= H. striata),

102 reaches the southern Nearctic region. The larva (first instar) and egg case of H larvalis were described by Spangler & Cross (1972).

Bionomics: Not much is known on the ecology and life history of this genus. Helobata species seem to be rare and difficult to collect; they can be found in ponds or slow moving creeks or rivers, living among the littoral vegetation or on floating plants. Females carry the egg cases on the underside of the abdomen; the developmental period of the eggs is unknown. Information on the feeding habits of the larvae is unknown, but they are probably predatory as all other known hydrophilids.

16- Enochrus Thomson (Figures 55-57)

Egg case: Variable in shape, from cup-shaped to fairly elongate; mast may be present or absent, when present more or less long, flat, extending to the water’s surface. Egg cases can be constructed on floating vegetation, beneath the water’s surface, or at the water’s edge, on grass or other substrates. Number of egg varies with the species from 8 to 30. In some cases the egg case may be absent.

Larva: Head capsule: Subquadrate; labroclypeus asymmetrical; nasale obliquely truncate, irregular, left side shorter than right, with four to six short teeth; lateral lobes of epistome also asymmetrical, unequal in length, rounded to pointed, longer to shorter than nasale. Frontal sulci as an inverted bell, fusing before reaching occipital foramen; coronal sulcus present, very short. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, subtriangular.

103 Antennae: Three-segmented. First segment as wide as second segment, shorter than second in first instar larvae, and as long as second in third instar larvae; second segment carries an apical sensory appendage shorter than third segment.

Mandibles: Strongly asymmetrical; right mandible with two strong inner teeth on basal half, inner margin of teeth and distal part of mandible serrated; left mandible with one inner tooth, distal inner margin of mandible serrated.

Maxillae: Five-segmented. Cardo small, subtriangular; stipes wide and longer than remaining segments combined, with five strong setae on inner margin; palpifer short, subrectangular, wider than long, carrying and apical galea as long or longer than first palpal segment. Palpi three-segmented, first segment the shortest, second and third segments subequal in length.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subpentagonal, slightly wider than mentum; mentum subquadrate, with a triangular area of strong cuticular spines at the base in dorsal view; prementum subtrapezoidal, wider at base. Palpi two-segmented, first segment short, second segment two to three times longer than first; membrane between prementum and palps, and between palpal segments with several flat, long spines; ligula present, very slender, as long or longer than first palpal segment.

Thorax and legs: Prothorax completely covered by a dorsal shield, with sagittal line; prostemum with a large subtrapezoidal plate divided by a sagittal line. Mesothorax and metathorax with two pairs of dorsal sclerites, anterior one narrow, posterior one larger

104 and irregular in shape; plates on metanotum smaller than those of mesonotum. Legs five-segmented, well developed, visible in dorsal view.

Abdomen: Ten-segmented; segments nine and ten reduced. Segments one to seven similar in shape and size, subdivided into three of four transverse folds; segment one with a pair of small suboval tergal plates, remaining segments with at most a pair of sclerotized dots/points. Stemites three to seven each with a pair of “prolegs”, appearing as prominent tubercles with several curved spines or hooks on the ventral surface. Segment eight with a large suboval tergite. Segment nine trilobed, carrying a pair of short one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With two well developed supraorbital styli. Thorax: Pronotum with 24 styli, 20 on the margins, and two pairs on disc of pronotum. Mesothorax and metathorax each with one pair of styli near midline. Abdomen: First segment with two pairs of dorsal styli; segments two to seven with three pairs of dorsal styli; pleurites of segments two to seven each with one stylus. Segment eight with a pair of small styli near midline. Segment nine with one pair of long cerci.

Number of species and distribution: Enochrus is a large genus, with about 170 described species, Worldwide in distribution. There are around 53 species in the New

105 World, 24 Nearctic (Gundersen 1978), and the rest Neotropical. The immatures of several species have been described: the egg case of E. vulgaris and E. scutellaris (Ferndndez 1992); all the stages of E. perplexus (Richmond 1920); all the stages of E. pygmaeus nebulosus and egg case and larva of E. dijfusus (Wilson 1923b); Richmond (1920) also provides a few notes on the egg cases and larvae of E. ochraceus, E. cinctus, and E. hamiltoni.

Bionomics: Adults are aquatic or semiaquatic, living on aquatic vegetation either littoral or floating, they can also be found on the debris, under rocks or pieces of wood at the water’s edge. Adults feed on algae and decaying plant material. Egg cases are laid beneath the water’s surface in most cases; in some instances such as E. cinctus the eggs are laid in the soil, near the water, without a silk cover (Richmond 1920, personal observations). Larvae hatch after four to seven days, and are predaceous, also cannibalistic. Larval development varies among species, ranging from one to two months. Pupation usually takes place in a pupal cell, dug in soil near the water; in some instances they may pupate in a nest of algae or under rocks (Richmond 1920, Bpving & Henriksen 1938). The pupa of one European species was found within the stems of a marshy plant, Phellandrium sp. (Schlik 1859).

17- Helocombus Sharp (Figure 58)

Egg case: Unknown

106 Larva: Head capsule: Subquadrate; labroclypeus slightly asymmetrical; nasale with two strong teeth on each side, and several small teeth on midregion; lateral lobes of epistome pointed, projecting as far as lateral teeth of nasale. Frontal sulci U-shaped, fusing before reaching occipital foramen, coronal sulcus present, very short. Gular sclerite absent; no reference to stemmata and cervical sclerites in original description (Perkins & Spangler 1981).

Antennae: Three-segmented. First segment slightly longer than second, both of the same width; sensory appendage on second segment half the length of third segment.

Mandibles: Symmetrical, sharply pointed, with two inner teeth at midlength; distal tooth larger. Inner margin of mandible serrated from apex to distal tooth.

Maxillae: Five-segmented. Cardo small, subtriangular; stipes wide and longer than remaining segments combined, with four strong setae on inner margin. Palpifer subquadrate, carrying an apical galea as long as first palpal segment. Palp three- segmented, first segment the shortest, second and third segments equal in length.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subpentagonal, wider than other segments; mentum subtrapezoidal, distal margin wider, with numerous cuticular spines on dorsal surface; prementum also subtrapezoidal, basal margin wider, with several long spines on dorsal surface at both sides of ligula. Palpi two-segmented, segment one half the length of segment two, with a row of apico-dorsal spines; segment two with a row of long dorsal spines at midlength. Ligula present, slender, as long as first palpal segment.

107 Thorax and legs: Prothorax completely covered by a large dorsal plate; prostemal plate large, subrectangular. Mesonotum and metanotum with tergites similar in size. Legs five-segmented, well developed, visible in dorsal view.

Abdomen: Ten-segmented; segments nine and ten reduced. Segments one to seven similar in size and shape, subdivided by transverse folds; without tubercles or projections. Segment eight with a large oval plate, emarginated at the caudal end. Segment nine trilobed, carrying a pair of small urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Unknown

Number of species and distribution: Monotypic genus, eastern Nearctic in distribution. The first instar larva of H. bifidus was described by Perkins & Spangler (1981).

Bionomics: Very little is known about this genus. Adults can be collected in woodland ponds (Perkins & Spangler 1981, personal observations). Young (1954) mentions collecting adults in sluggish streams and pools in hammocks in Florida).

108 18- Cymbiodyta Bedel (Figures 59-60)

Egg case: Laid on the underside of rocks, pieces of wood, leaves or in moss near the water’s edge. The silk cover is very loose, no mast is present. Number of eggs varying between 15 and 40. Two species reared by me (Cymbiodyta vindicata and Cymbiodyta sp.) laid egg masses in small depressions, excavated in mud, by the water’s edge, no egg case was seen.

Larva: Head capsule: Subquadrate; labroclypeus slightly asymmetrical; nasale with usually seven small, irregular teeth, some of which may be grouped and bifid; lateral lobes of epistome slightly asymmetrical, rounded to triangular, not exceeding teeth of nasale. Frontal sulci shaped as an inverted bell, converging before reaching occipital foramen; coronal sulcus present, very short. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, small and narrow.

Antennae: Three-segmented. First instar larvae with first segment as wide and half as long as second; second and third instars with first and second segments subequal in length; third segment the shortest. Sensory appendage on second segment slightly shorter to half the length of third segment.

Mandibles: Slightly asymmetrical, with two inner teeth at midlength of mandible. Distal tooth larger. Inner margin serrated from apex to distal tooth; inner margin of distal tooth also serrated. No molar area present.

109 Maxillae: Five-segmented cardo small, subdivided, irregularly shaped. Stipes strong, as long as remaining segments combined, with five strong setae on inner margin. Palpifer subrectangular, wider than long, carrying an apical galea slightly shorter than first palpal segment. Palpi three-segmented; first segment the shortest, second and third segments subequal in length.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subpentagonal, mentum subtrapezoidal to subquadrate, distal margin wider than basal one, dorsally with a group of cuticular spines on basal half; prementum also subtrapezoidal, basal margin wider. Palpi two-segmented, second segment three times longer than first; membranes between prementum and first palpal segment, and between palpal segments with several long, flat spines. Ligula present, slender, slightly longer than first palpal segment.

Thorax and legs: Prothorax covered by a large dorsal shield, with sagittal line; prosternum with a large subrectangular plate, sagittal line absent. Mesothorax with two large subrectangular plates; metathorax with two narrow subrectangular sclerites. Legs five-segmented, well developed, easily seen in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in size and shape, subdivided into three or four transverse folds, each segment carrying a pair of narrow transversal tergites, becoming smaller towards the posterior end of the body; pleural areas lobed. Segment eight with a suboval dorsal plate. Segment nine trilobed, carrying a pair of short one-segmented urogomphi.

110 Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With two pairs of supraorbital styli. Thorax: Pronotum with 24 styli, 20 on the margins, and a transverse row of four on disc. Mesonotum with one stylus on each side of scutellum; metanotum with one pair of styli near midline. Abdomen: Segment one with a transverse row of four styli of tergum; segments two to seven with a row of six styli on tergum; one stylus on each pleura. Segment eight carries one pair of styli; segment nine with a pair of long cerci.

Number of species and distribution: The genus Cymbiodyta is mainly Nearctic in distribution, including the northern parts of Central America and one widely distributed Palaearctic species. There are 29 species; Richmond (1920) and B0ving & Henriksen (1938) described the immatures of a species identified as C. fimbriata, according to Smetana (1974) a synonym of C. semistriata.

Bionomics: Adults live in aquatic and semiaquatic habitats, such as moss or leaf debris gathered at the water’s edge. Aquatic habitats include both stagnant and running water. I have collected them among grass in temporary pools by the side of roads, and also in moss near small creeks and waterfalls in wooded areas. Females cover the eggs with a fine mesh (Richmond 1920), or lay them in small depressions excavated in mud or soil (personal observation) without any cover. The eggs hatch in four or five days. Larvae are predatory, and also cannibalistic, feeding on unhatched eggs of their own species.

I ll Larval development ranges from three weeks (personal observations) to about two months (Richmond 1920). Cymbiodyta prepupae pupate near the water’s edge; the length of the pupal stage is unknown.

19- Chasmogenus Sharp (Figures 61-62)

Egg case: Females dig a small depression in the soil where they lay their eggs, surrounding them with a fine silk layer; no mast is present. The number of eggs ranges between 18 and 25.

Larva: Head capsule: Subquadrate, labroclypeus apparently symmetrical; nasale with five strong teeth, equal in length; lateral lobes of epistome rounded, projecting as far as teeth of nasale. Frontal sulci converging towards occipital foramen, fusing before reaching it; coronal sulcus present, short. Six stemmata on each side of head. Gular sclerite absent, no reference to cervical sclerites in original description (Anderson 1976).

Antennae: Three-segmented. First segment the longest; second segment carrying an outer apical sensory appendage; third segment apparently slightly longer than sensory appendage.

Mandibles: Strongly asymmetrical. Right mandible with two strong teeth on basal half of inner margin, similar in size; left mandible with only one inner tooth; distal inner margin of both mandibles slightly serrated. No molar area present.

112 Maxillae: Five-segmented. Stipes wide and longer than remaining segments combined; palpifer longer than wide, carrying an apical galea. Palpi three-segmented; second segment the longest, as long as first and third combined.

Labium: Formed by submentum, mentum, and prementum. Submentum subtriangular, longer than wide; mentum swollen at middle, slightly narrower than submentum; prementum subtrapezoidal, narrower than mentum. Palpi two-segmented, second segment three times longer than first. Ligula present, narrow, twice as long as first palpal segment.

Thorax and legs: Prothorax as wide as head, weakly sclerotized, with sagittal line; prostemum with a subrectangular plate, with sagittal line. Mesothorax and metathorax without sclerotized plates. Legs five-segmented, well developed, easily seen in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in size and shape, with transversal folds, without tergal plates. Abdominal “prolegs” present, large, with small apical setae (spines). Segments eight and nine forming a small spiracular atrium, tergite of segment eight poorly sclerotized.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, functional but smaller than those in other genera, within the spiracular atrium.

Pupa: Head: With two pairs of supraorbital styli.

113 Thorax: Pronotum with 24 styli, 20 on margins and a transversal row of four on disc. Mesonotum with one stylus on each side of scutellum; metanotum with one pair of styli near midline. Abdomen: First abdominal segment with one pair of styli near midline; abdominal segments two to seven with a transverse row of six styli on tergum, also one stylus on each pleurite. Segment nine with two short, thick cerci.

Number of species and distribution: This is a small genus, with 24 species (Hebauer 1992). The genus is subdivided into two subgenera: 1- Ch. (Chasmogenus) with three Neotropical species, and 2- Ch. (Crephelochares) with 21 species, most of them in the Ethiopian (Afrotropical) region, and a few in the Australian, Oriental, and Palaearctic regions. The immature stages and life cycle of the Australian Ch. (Crephelochares) nitescens have been described by Anderson (1976), under the name Helochares nitescens.

Bionomics: Little is known about this genus; most records are from specimens collected at light traps (Heabuer 1992). They seem to prefer stagnant or slow flowing waters. The specimens collected and reared by Anderson (1976) came from the mud at the edge of a small stream. The egg cases made by females have a very thin silk cover, and are placed in a small depression in the soil. Larvae hatch after five to seven days; they are predatory, feeding on small invertebrates. Larval development takes from three to four weeks. Pupation under laboratory conditions took place in moss, with the pupae completely exposed, and the pupal stage was only three to four days.

114 20- Hydrobius Leach (Figures 63-65)

Egg case: Bag-shaped, almost spherical, made of two layers of silk, first one forming the bag where the eggs are deposited, second one forming the cap, which is continuous with a flat flare surrounding it; flare is variable in width, it does nor form a proper mast. Number of eggs varies from 13 to 25.

Larva: Head capsule: Subquadrate; labroclypeus asymmetrical; nasale with five irregular teeth, obliquely truncate, right side longer; lateral lobes of epistome almost symmetrical, rounded, not exceeding nasale, margins with seven strong curved setae. Frontal sulci irregularly V-shaped, converging before occipital foramen; coronal sulcus present, short. Six stemmata on each side of head, gular sclerite absent; cervical sclerites present, suboval.

Antennae: Three-segmented. First segment subequal in length to second in first instar larvae, twice the length of second segment in third instar larvae. Sensory appendage on second segment very small; third segment half to one third the length of second segment.

Mandibles: Symmetrical, sharply pointed; with three inner teeth at midlength. Basal tooth much smaller than distal two. No molar area.

Maxillae: Five-segmented. Cardo small, subdivided and subtriangular; stipes about the same length than remaining segments combined in first instar larvae, slightly longer in third instar larvae; with a row of five inner setae on inner margin, and a tuft of strong

115 spines at the base. Palpifer short, incompletely sclerotized, subrectangular, carrying an apical galea as long as first palpal segment. Palpi three-segmented, first segment very short; second segment the longest. Palpifer and first two palpal segments with small spines on inner and dorsal surface.

Labium: Formed by submentum, mentum, and prementum. Submentum large, irregular in shape; mentum subtrapezoidal, wider at base, with strong cuticular spines on dorsal surface. Prementum subquadrate, with a few minute spines on dorsal surface. Palpi two-segmented, first segment very short, second segment three to four times longer; both segments with small spines on dorsal surface. Ligula present, slender and long, twice the length of first palpal segment.

Thorax and legs: Prothorax covered by a large dorsal shield, with sagittal line, with a row of fine setae on anterior margin; prosternum with a large subrectangular plate, with sagittal line. Mesothorax with two pairs of tergites, anterior one small, narrow, posterior one large, subtriangular; metathorax with one pair of irregular tergites. Legs five-segmented, well developed, not very long, visible in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in size and shape, subdivided into three transverse folds; first fold with two sclerotized patches, larger on segment one and two; third fold with two or four tubercles. Pleural areas slightly lobed (H. fuscipes) to strongly lobed ( H. melaenus). Segment eight smaller, with a large subquadrate plate; segment nine trilobed, with a pair of small one-segmented urogomphi.

116 Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With one pair of supraorbital styli. Thorax: Pronotum with 20 styli; 18 on margins of pronotum and two on disc. Mesothorax with one stylus on each side of scutellum; metanotum with one pair of styli near the base of wingpads. Abdomen: Segments one to seven with a transverse row o four tergal styli; pleurites one to seven with one stylus. Segment eight with one pair of short styli; segment nine carrying a pair of medium sized cerci.

Number of species and distribution: Small genus, with only six species; Nearctic and Palaearctic in distribution. Three species are known from North America, H. melaenus, H. tumidus, and the Holarctic H. fuscipes. Richmond (1920) describes the egg case and larval stages of H. globosus (= H. melaenus)', the immature stages of H. fuscipes are treated by several authors: Cussac (1855), Schiodte (1862, 1872), Balfour-Browne (1910), Wessenberg-Lund (1913), and B0ving & Henriksen (1938).

Bionomics: Balfour-Browne (1910) provides the most detailed description on the life cycle of H. fuscipes, Richmond (1920) and B0ving & Henriksen (1938) also provide useful information on the biology of both H. fuscipes and H. melaenus. Adults of H. melaenus seem to prefer streams, small creeks, or spring-fed pools with abundant vegetation; on the other hand the adults of H. fuscipes prefer stagnant waters, being common in woodland pools (personal observations). Adults feed on algae and

117 decaying plant material, but they will also take dead larvae or snails (Balfour- Browne 1910). The females lay the egg cases in the mud or moss near the water, or on blades of grass or other floating vegetation, away from the water’s edge. Females take about two hours to spin the egg case. The number of egg is variable, ranging between 13 and 25, and females can lay up to four or five egg cases in one breeding season. Larvae hatch after one or two weeks, they are predaceous on other small arthropods,they are also cannibalistic. Larval development is slow, taking about two months. I have collected overwintering adults and third instar larvae during the winter and early spring, they are usually under rocks or among leaf debris at the margins of creeks.

21- Hydramara Knisch (Figures 66-67)

Egg case: Unknown.

Larva: Head capsule: Subquadrate; labroclypeus asymmetrical; nasale prominent, obliquely truncated, left side shorter, with five teeth; lateral lobes of epistome rounded, shorter than nasale, medially with a row of strong curved setae. Frontal sulci irregularly V- shaped, fusing before reaching occipital foramen; coronal sulcus present, rather short. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, subtrapezoidal.

Antennae: Three-segmented. Segment one longer than remaining segments combined; second segment carrying a very small apical sensory appendage; third segment the

118 shortest.

Mandibles: Symmetrical, sharply pointed, with three inner teeth at midlength; basal tooth very small, apical two teeth subequal in size. No differentiated molar area.

Maxillae: Five-segmented. Stipes as long as remaining segments combined, with a row of nine strong setae on inner margin; palpifer subrectangular, slightly longer than wide; bearing an apical galea almost as long as first palpal segment. Palpi three-segmented; first and third segments short, subequal in length; second segment the longest.

Labium: Formed by submentum, mentum, and prementum. Submentum subtrapezoidal, rounded posteriorly; mentum subquadrate, narrowed medially, with dorsal surface covered by numerous spines and long apico-lateral setae. Prementum subquadrate, in dorsal view with a row of apical setae at the base of palpi. Palpi two- segmented, second segment short, two to three times the length of first. Ligula present, slender, slightly shorter than first palpal segment, subdivided at basal third.

Thorax and legs: Pronotum almost completely covered by a large dorsal shield, with sagittal line. Prosternum large, subrectangular, lacking sagittal line. Mesothorax with two pairs of dorsal sclerites; anterior one transverse, small and narrow; posterior one large, subtriangular. Metathorax with two pairs of dorsal sclerites; anterior one larger, transverse, roughly elliptical; posterior one small, irregular in shape. Legs five- segmented, well developed, easily seen in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in size and shape, subdivided into four transversal folds; segment one with a

119 pair of large subtriangular sclerites; segments two to seven also with a pair of sclerites, becoming increasingly smaller; transverse folds with patches of asperities and tubercles; pleurites strongly lobed. Segment eight with a suboval dorsal plate; segment nine trilobed, carrying a pair of short, one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, functional but smaller than those in other genera, within the spiracular atrium.

Pupa: Unknown.

Number of species and distribution: Hydramara is a monotypic genus; the only known species, H. argentina, is known from a few localities in central and northwest Argentina. Spangler (1979) described a third instar larva associated with adults of H. argentina, which he assigned to that species.

Bionomics: Very little is known about this genus. Adults live in montane streams (Spangler 1979) under rocks or among drift wood and debris.

22- Tropistemus Solier (Figures 68-70)

Egg case: Egg cases laid on aquatic vegetation, either littoral or floating. Bag shaped, made of two layers of silk; first one forming the cup which contains the eggs; second one forming the cap covering the eggs and continues into the mast. Mast variable in length, from very short (or missing) to several times the length of the cup; usually

120 ribbon-like, depending on the species can be soft or stiff. Number of eggs varying from five to 25.

Larva: Head capsule: Subtrapezoidal, wider at anterior margin; labroclypeus symmetrical to slightly asymmetrical; nasale not prominent, with five to seven short teeth; lateral lobes of epistome rounded, projecting as far or slightly farther than teeth of nasale. Frontal sulci V-shaped, coming together before occipital foramen; coronal sulcus present, short. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, suboval.

Antennae: Three-segmented, very long. Segment one slender, longer than remaining segments combined, one and a half times longer in first instar larvae, almost three times longer in third instar larvae. Second segment as long as third; sensory appendage of second segment reduced.

Mandibles: Asymmetrical, sharply pointed. Right mandible with three teeth on basal half. Distal tooth large, in most species bifid apically, with outer margin serrated; inner margin of distal tooth and base of mandible forming a groove, dorsal and ventral margins of groove each with a small tooth, subequal in size. Left mandible similar to right one, except for basal two teeth, placed on ventral margin of groove, middle one larger than basal one.

Maxillae: Five-segmented, long. Cardo small, subtriangular. Stipes slender and longer than remaining segments combined; one and a half times longer in first instar larvae, and two times longer in third instar larvae; with four setae on inner margin; palpifer

121 slender, carrying a short apical galea. Palpi three-segmented; first segment the shortest, second segment three to four times longer than first; third segment slightly shorter than second.

Labium: Formed by submentum, mentum, and prementum. Submentum large, wide, irregular in shape, with posterior margin rounded. Mentum subquadrate, wider at middle, with antero-lateral edges slightly projected forward; basal half of dorsal surface with small cuticular spines, also with several short setae on distal half; prementum slender, half the width of mentum. Labial palpi two-segmented; first segment short, second segment four to five times longer, Ligula long, slightly shorter than second palpal segment, constricted subapically.

Thorax and legs: Pronotum large, covering most of prothorax, with sagittal line; prosternum with a large subrectangular plate, sagittal line only on distal half. Mesothorax with two large subtriangular dorsal plates; metathorax with two smaller irregularly dorsal plates. Legs long, five-segmented, easily seen in dorsal view; femur and tibiotarsus with a fringe of long swimming hairs on inner margin.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in shape, narrowing towards caudal end; subdivided into two or three transversal folds; anterior fold of first segment with a pair of small, reduced tergal plates; posterior fold in segments one to seven with a transverse row of four tubercles carrying slender apical setae. Pleurites one to seven with rather long tubercles, with long setae at apex. Segment eight with a large subcircular plate, carrying four lobes on caudal end. Segment nine trilobed, carrying a pair of small, one-segmented urogomphi.

122 Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: Without supraorbital styli. Thorax: Pronotum with 22 styli, 20 on the margins, two on disc. Mesonotum with one stylus on each side of scutellum; metanotum with one pair of styli close to the base of wingpads. Abdomen: Tergitesone to seven with a transverse row of four styli; pleurites two to seven, each with one stylus. Segment eight with one pair of small styli; segment nine carrying a pair of strong cerci, bifid and pointed at the apex, with two preapical spines on each cercus.

Number of species and distribution: Tropistemus is a New World genus, with almost 60 described species. The immatures of several species have been described: Duges (1884) describes the immatures of T. lateralis', Richmond (1920) describes those of T. glaber; Wilson (1923b) redescribes T. lateralis and T. glaber, and adds those of T. mixtus’, Spangler (1965) describes the larva of T. collaris; Hosseinie (1976a, 1976b) describes the immatures and life cycle of T. lateralis, T. collaris, and T. blatchleyi; Fortich (1979) describes the immatures and life cycle of T. setiger, finally Ferndndez (1980) describes those of T. ignoratus.

Bionomics: Detailed information on the bionomics of Tropistemus is available in Richmond (1920), Wilson (1923b), Young (1958), Spangler (1960), Hosseinie (1976a, 1976b), and Fortich (1979). Adults are aquatic, very good swimmers, living in

123 the littoral zone of ponds, lakes, slow running creeks or rivers, and also in temporary rain pools. Male and females undergo a fairly elaborated mating process including sound signals, females spin the egg cases on the aquatic vegetation or on sticks or rocks emerging out of the water; the masts always seem to reach the water’s surface. Sometimes, egg cases can be laid in groups, one on top of the other. The number of eggs varies with the species from 5 to 25. larvae hatch after five to seven days; they are very active and voracious, feeding on other small invertebrates, they are also cannibalistic. Larval development depends on the species, taking from two weeks to two months (personal observations). Prepupal stage is about two to three days, and pupation occurs in a pupal chamber dug in soil. The pupal stage is five to seven days, but the adults remain in the pupal chamber for one or two days before emerging. Species in temperate and cold regions overwinter, but in areas with a moderate climate Tropistemus are active all year round, being multivoltine.

Additional comments: Species of the genus Tropistemus have been the subject of different behavioral, ecological, and biogeographical studies. Ryker (1972, 1975, 1976, 1976a, 1994) studied in detail the mating process and sound production of several Nearctic species. Hosseinie (1976b) examined the effect of the amount of food during the development of T. lateralis. Young and Spangler (1956), Young (1961, 1965, 1966, 1967), Dancis (1967), and Wooldridge (1962, 1964, 1965) provide several studies dealing with biogeographical aspects of this genus, as well as with hybridization and color patterns. Formanowicz & Brodie (1988) studied prey density and its effect on feeding behavior of T. lateralis larvae; Walton et al. (1990) mention the effect of T. lateralis larvae on populations of Culex tarsalis. Finally, Femdndez (1983) did a year­ long populational study of T. setiger.

124 23- Hydrobiomorpha Blackburn (Figures 71-72)

Egg case: Unknown.

Larva: Head capsule: Subquadrate; labroclypeus slightly asymmetrical; nasale obliquely truncate, left side slightly shorter, with five inconspicuous teeth; lateral lobes of epistome triangular, projecting farther than nasale, finely serrated on inner margin. Frontal sulci V-shaped, meeting before reaching occipital foramen; coronal sulcus present, short. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, subrectangular.

Antennae: Three-segmented, long. First segment slender, three times longer than remaining segments combined (first instar larva); second segment as long or slightly longer than third. Sensory appendage of second segment reduced.

Mandibles: Symmetrical, sharply pointed, with two inner teeth on basal half; distal tooth large, bifid at apex; basal tooth very small. No molar area.

Maxillae: Five-segmented. Stipes slender, longer than remaining segments combined; palpifer slender, carrying a short apical galea. Palpi three-segmented, first segment the shortest, second and third segments subequal in length.

Labium: Formed by submentum, mentum, and prementum. Submentum subpentagonal, rounded posteriorly. Mentum subtrapezoidal; antero-lateral angles

125 slightly projected; dorsal surface with several short setae; postero-lateral angles each with a pair of small denticles. Prementum longer than wide, half the width of mentum. Palpi two-segmented, distal segment four times longer than basal segment; ligula present, twice as long as basal palpal segment.

Thorax and legs: Pronotum covered by a large dorsal shield, posterior end rounded, sagittal line present; prostemal plate large, subrectangular, with sagittal line. Mesothorax and metathorax with subtrapezoidal tergites, wider anteriorly, sagittal line present. Legs five-segmented, long, visible in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. Segment one subdivided into two transversal folds, with a pair of narrow anterior sclerites; segments two to seven subdivided into four or five transversal folds, without sclerites. Segments one to seven with eight setose tubercles, four dorsal and two on each lateral margin; pleurites lobed. Segment eight with a small suboval tergal plate, posterior apex subdivided into four lobes; a pair of long procerci on sides of tergal plate. Segment nine round, with three small sclerites, carrying a pair of short one-segmented urogomphi, and a pair of long paracerci; a pair of gill-like appendages originates on ventral side.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Unknown.

126 Number of species and distribution: Hydrobiomorpha is a fairly large genus, with about 50 described species. Most species are Neotropical (Bachmann 1988), there is one in the southern Nearctic region, and the rest are from the Ethiopian, Oriental, and Australian regions; there is a single species in the Palaearctic region. Spangler (1973) described the first larval instar of the New World H. casta\ Bertrand (1962) gave a brief description of the larva of an Ethiopian Neohydrophilus (= Hydrobiomorpha).

Bionomics: Very little is known about this genus. Adults and larvae are aquatic; Young (1954) mentions collecting H. casta in cypress ponds, roadside ditches, and swamps in the flatwoods in Florida. I have collected them in large numbers at lights, also in Florida, and among floating vegetation in the Parand Delta in Argentina.

24- Hydrochara Berthold (Figures 73-75)

Egg case: Laid on the water’s surface, floating, usually covered by a dead leaf or among masses of floating algae. Elongated, 10 to 18 mm long and 9 to 10 mm wide, subtriangular in cross section. White in color, except for cap closing the case and mast that are brown. Mast horn-shaped, arising vertically over the water’s surface. There are 40 to 60 eggs in each case, placed vertically inside the sac.

Larva: Head capsule: Subtrapezoidal, wider at anterior end; labroclypeus almost symmetrical, broad, slightly projected on anterior margin, with a few small teeth; lateral lobes of epistome rounded, projecting as far as nasale, with several strong setae on margin. Frontal sulci irregularly V-shaped, converging at the occipital foramen; coronal sulcus

127 extremely short, almost undistinguishable. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present; subtriangular.

Antennae: Three-segmented, long and slender. First segment slightly longer than other two combined in first instar larvae, two to three times longer than other two combined in third instar larvae, with a row of long setae on inner margin. Second segment slightly longer than third segment, curved inwards, with sensory appendage reduced.

Mandibles: symmetrical, with two inner teeth; distal tooth large; basal tooth small, with small toothlet near apex in first instar larvae. No molar area present.

Maxillae: Five-segmented. Cardo small, subtriangular. Stipes slender, as long as remaining segments combined in first instar larvae, almost one and a half times longer in third instar larvae; palpifer longer than wide, slender, carrying a short apical galea. Palpi three-segmented, basal segment the shortest, second and third segments subequal in length, each twice as long as first segment.

Labium: Formed by submentum, mentum, and prementum. Submentum wide, subtriangular, with posterior margin curved; mentum subtrapezoidal, basal margin wider, coarsely serrated on the sides, with pointed antero-lateral margins; basal third of dorsal surface covered by fine cuticular spines; prementum rectangular, longer than wide. Palpi two-segmented, second segment three to four times longer than first; ligula present, slightly shorter than first palpal segment.

Thorax and legs: Pronotum covering most of prothorax, with saggital line; prostemum with a large sclerite, no sagittal line present. Mesonotum and metanotum each with a

128 pair of irregularly shaped tergites, those of metanotum slightly smaller. Legs five- segmented, long, visible in dorsal view; femora and tibiotarsi with fringes of long swimming hairs.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in shape, subdivided into two folds; segment one with a pair of small anterior tergites; segments two to seven with smaller sclerotized patches on anterior fold; posterior fold with a transverse row of four tubercles. Pleural areas carrying a long pubescent appendage. Segment eight with a small subquadrate tergite,with four lobes on posterior margin. Segment nine trilobed, carrying a pair of small two-segmented urogomphi; a pair of gill-like appendages originates on venter.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With two pairs of orbital styli. Thorax: Pronotum with 32 styli, 30 on the margins and one pair on disc. Mesothorax with one stylus on each side of scutellum; metathorax with one pair of styli near midline. Abdomen: Segments one to seven with a transverse row of six styli, outer ones longer; pleural areas each with one stylus. Abdominal segment eight with two pairs of styli on posterior margin. Cerci as long as seventh and eighth segments combined, diverging and annulated, trifid at the apex.

129 Number of species and distribution: Rather small genus, with 22 described species. It is present in the Nearctic, Palaearctic, Ethiopian, and Oriental regions, and is missing from the Neotropical and Australian regions. The immature stages of H. obtusata were described in detail by Richmond (1920) and Wilson (1923b); Bowditch (1884) describes the egg case and larva of this species, and Whickman (1895) describes the larva and pupa of the same species. Matta (1982) describes the larvae of H. soror and H. occulta.

Bionomics: Detailed information on the bionomics of Hydrochara is provided by Richmond (1920) and Matta (1982). Adults and larvae live in woodland pools, or shallow bodies of standing water. H. lineata (from the southwestern Nearctic region) seems to prefer clear, mineralized waters, and can also be found in hot springs. Females spin large, free-floating egg cases, using dead leaves or other plant material as support. Depending on the species, the number of eggs ranges from 40 to 60. First instar larvae hatch after six or seven days, and they are predatory. Studies by Formanowicz et al (1982) give detailed information on the ambush-site predatory behavior of H. obtusata larvae. Prey for the larvae are all kind of aquatic invertebrates, larger larvae can also prey on small tadpoles. The developmental time of these larvae is fast, about 30 days (Bowditch 1884). Pupation takes place in the soil, near the water; the pupal period is about five to seven days, and pupae are greenish in color (Richmond 1920).

130 25- Dibolocelus Bedel (Figures 76-78)

Egg case: Laid on the water’s surface, floating, using dead leaves as support. Subtriangular in cross-section,with curved base, 23 to 28 mm long and 15 to 18 mm wide. White in color, except for cap closing the case and mast which are brown. Mast long, horn-shaped, circular in cross section, forming a tube, arising vertically over the water’s surface. Number of eggs 28 to 36.

Larva: Head capsule: Suboval; labroclypeus symmetrical; nasale short, poorly developed, covered by dense pubescence; antero-lateral lobes of epistome rounded, projecting slightly farther than nasale, each with two strong setae projecting mediad. Frontal sulci U-shaped, fusing before reaching occipital foramen; coronal sulcus present, very short. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, narrow, suboval.

Antennae: Three-segmented in first instars, four-segmented on third instars. First segment slender, longer than remaining segments combined, with several strong setae on inner margin; second segment very short in third instar larvae; third and fourth segments subequal in length, each three times longer than second. Second segment constricted near base in first instar larvae. Sensory appendage of second segment (in first instars) of third segment (in third instars) reduced.

Mandibles: Strongly asymmetrical; right mandible longer, more slender, with one blunt tooth on inner margin; left mandible shorter, lacking teeth, with a concavity on basal third.

131 Maxillae: Five-segmented. Cardo small, irregularly subtriangular. Stipes wider and longer than remaining segments combined, with four strong setae on inner margin; palpifer longer than wide, carrying a short apical galea. Palpi three-segmented, first and second segments subequal in length, third segment slightly shorter, conical.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subpentagonal; mentum smaller, subtrapezoidal, basal margin wider, distal margin with apico-lateral lobes, dorsal surface rugose and with several short spines; prementum small, subtrapezoidal, longer than wide, distal margin wider. Palpi two-segmented, first segment slightly shorter than second; ligula present, small, half the length of first palpal segment.

Thorax and legs: Pronotal shield covering most of dorsal surface of prothorax, with sagittal line; prostemal sclerite subrectangular, with sagittal line. Mesothorax and metathorax each with a pair of subtriangular tergites. Legs five-segmented, long, visible in dorsal view; femur and tibiotarsus with rows of swimming setae.

Abdomen: Ten-segmented, segments nine and ten reduced; abdominal segments covered by a fine pubescence in first instar larvae, covered by asperities in second and third instar larvae. Segments one to six similar in size and shape, segments seven and eight more elongated and slender. Segments one to seven with four transversal folds; second fold with two tubercles; third fold with four tubercles. Pleurites one to eight each with a lobe carrying four long setae. Segment eight with two small subtriangular tergites at posterior end; segment nine slightly trilobed, with three tergites, carrying a pair of short one-segmented urogomphi, ventro-medially with a pair of gill-like

132 appendages.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With one pair of short supraorbital styli. Thorax: Pronotum with 26 styli, some barely protruding, all on margins; three large styli on each anterior margin, remaining styli very short; mesonotum with one stylus on each side of scutellum; metanotum with one pair of styli near midline. Abdomen: Segments one to seven with two pairs of styli; first pair small, near midline; second pair behind spiracles; each pleurite of segments two to seven with one short stylus, not visible in dorsal view. Segment eight with one pair of short styli; segment nine with a pair of annulated cerci, ending in claw-like structures, each with three or four points.

Number of species and distribution: Dibolocelus is a small genus, with about half a dozen described species, all from the New World. The immatures of D. ovatus were described by Archangelsky & Durand (1992a).

Bionomics: Detailed information on the life-cycle of D. ovatus is provided by Archangelsky & Durand (1992a). Both adults and larvae are aquatic; their habitat is not well known, but they seem to prefer large and deep bodies of water, with plenty of vegetation (Young 1954, Smetana 1988, personal observations). Adults are very good fliers, and are attracted to light traps. Females spin a large egg case using dead leaves as

133 a substrate; the time required to construct the egg case ranges between one and a half to two hours; the number of eggs is 28 to 36. Larvae hatch after five or six days; first instar larvae are very active, dispersing themselves by swimming away from the egg case. They are predatoiy, but not cannibalistic, feeding exclusively on snails (), crushing their shells with their strong mandibles. Larval development takes about 30 to 45 days. Pupation takes place in a pupal chamber dug in soil; the prepupae remain in this chamber for ten to 20 days before moulting into pupae; the pupal stage lasts five to seven days. The adults remain for two days within the pupal chamber before emerging.

Additional comments: Dibolocelus was created by Bedel (1891) as a subgenus of Stethoxus (= Hydrophilus); it was raised to generic level by Regimbart(1901); recently Hansen (1991), based on adult characters, downgraded it again as a subgenus of Hydrophilus. In the present work, based on both adult and larval characters, I prefer to consider Dibolocelus as a genus, a similar approach has been taken by other authors (see Jasper & Vogtsberger 1996). There are several adult characters that make the Dibolocelus species easily distinguished from those of Hydrophilus-. 1- prostemum open, with two conical protuberances in Dibolocelus versus prostemum closed, hooded in Hydrophilus-, 2- pubescence on abdominal stemites covering most of the last three visible abdominal segments in Dibolocelus versus pubescence of last two or three abdominal stemites restricted to the lateral areas in Hydrophilus; 3- Dibolocelus species are very convex, while Hydrophilus species are more flat. There are also several larval characters that help to distinguish these two genera: 1- the diet is restricted to snails in Dibolocelus, while Hydrophilus feeds on a number of different prey (from invertebrates to small fish and tadpoles); 2- Shape of mandibles different, especially the left mandible, lacking an inner tooth in Dibolocelus, which is present inHydrophilus-, 3- the setiferous lateral lobes of Dibolocelus are well developed, while those of the New

134 World species of Hydrophilus are reduced, appearing as a small tubercle; 4- the size and shape of the pronotal plates is different, subrectangular and with a narrow sagittal line in Dibolocelus, in Hydrophilus the pronotum has two irregular plates, well separated.

26- Hydrophilus Muller (Figures 79-81)

Egg case: Laid on the water’s surface, floating freely, using dead leaves that form the roof of the case, or included in sheets of algae or floating plants. Case oval in cross section, white in color except for mast and cap closing the case, which are brownish. Mast long, hom shaped, oval in cross section. Number of eggs from 60 to 130 in each case.

Larva: Head capsule: Suboval; labroclypeus slightly asymmetrical; nasale undeveloped; lateral lobes of epistome rounded to pointed, projecting farther than nasale. Frontal sulci U- shaped, fusing just before reaching occipital foramen; coronal sulcus present, veiy short. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, suboval.

Antennae: Three-segmented in first instars, four-segmented in third instars. First segment slender, longer than remaining segments combined, with a row of slender setae on distal two thirds of inner margin; second segment very short in third instar larvae; third and fourth segments subequal in length. Second segment constricted near base in first instar larvae, slightly shorter than third segment. Sensory appendage of

135 second segment (in first instars) or third segment (in third instars) reduced.

Mandibles: Asymmetrical; right mandible longer, more slender, with a bifid inner tooth on basal half; left mandible shorter, with one small inner tooth on basal half.

Maxillae: Five-segmented; cardo small, subtriangular. Stipes wider and longer than remaining segments combined, with three long stout setae on inner margin; palpifer longer than wide, carrying a short apical galea. Palpi three-segmented; first and second segments subequal in length; third segment slightly shorter.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subpentagonal; mentum smaller, asymmetrical, subtrapezoidal, distal margin with large apico-lateral lobes, basal third with small spines, distal two thirds with short and stout setae; prementum subtrapezoidal, distal end wider. Palpi two-segmented, first segment the shortest; ligula present, slightly shorter than first palpal segment.

Thorax and legs: Pronotal shield small, subdivided in two irregular plates, widely separated; prostemum with a large subrectangular plate, with sagittal line. Mesonotum and metanotum each with a pair of subtriangular plates, smaller than those of pronotum. Legs five-segmented, long, visible in dorsal view, with rows of long swimming setae on femur and tibiotarsus.

Abdomen: Ten-segmented, segments nine and ten reduced; abdominal segments covered by a fine pubescence in first instar larvae, third instar larvae with asperities as those of Dibolocelus, but less dense. Segments one to six similar in shape, tapering towards the caudal end; segments seven and eight more elongated and slender.

136 Segments one to seven subdivided into three transverse folds; third fold with four small tubercles. Pleurites one to eight with a small lateral setiferous tubercle (developed into a lobe in European species). Segment eight with two small subtriangular tergites at posterior end; segment nine slightly trilobed, with three tergites, carrying a pair of short one-segmented urogomphi, ventro-medially with a pair of long gill-like appendages.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With one pair of short supraorbital styli. Thorax: Pronotum with 22 styli, all on margins; three large styli on each anterior margin, remaining styli very short. Mesonotum with one stylus on each side of scutellum; metanotum with one pair of styli near midline. Abdomen: Segments one to seven with two pairs of styli; first pair small, near midline; second pair larger, near spiracles; pleurites two to seven each with one short stylus, difficult to see in dorsal view. Segment eight with one pair of short styli; segment nine with a pair of annulated cerci, ending in claw-like structures, each with two or three points (which may have small toothlets).

Number of species and distribution: Hydrophilus (including Temnopterus and Stethoxus, but excluding Dibolocelus) is a relatively large genus, with over 40 described species, Worldwide in distribution. About ten species are recorded from the New World. Immatures of H. triangularis have been described by many authors: Garman (1881), Matheson (1914), Richmond (1920), and Wilson (1923a); from South

137 America the only described species is Hydrophilus ensifer (= H. ater), by Costa et al. (1988).

Bionomics: Detailed information on the bionomics of Hydrophilus is provided by Riley (1881), Miall (1895), Wilson (1923a), Wesenberg-Lund (1913, 1915), and Bpving & Henriksen (1938). Adults and larvae live in ponds with plenty of vegetation. Adults are very good swimmers, and feed mainly on plant material, but they also prey on other organisms, including small fish. The construction of the egg case takes between one and a half to five hours, depending on the species (Miger & Lancret 1804, Lyonet 1832, Wilson 1923a). The egg case floats freely on the water’s surface and can contain up to 130 eggs. Larvae hatch after four to seven days, and larval development is rather fast for such a large species, about 30 days (personal observation); larvae are predaceous and cannibalistic, preying on a variety of organisms, including other arthropods, snails, tadpoles, and small fish. The prepupal period is long, up to two weeks, and pupation occurs in a large pupal chamber constructed in the soil, not far from the waters edge. Pupal development ranges between six to ten days (Bpving & Henriksen 1938, personal observations).

Additional comments: Refer to the same section in Dibolocelus.

27- Cylorygmus d’Orchymont (Figures 82-84)

Egg case: Unknown.

138 Larva: Head capsule: Subquadrate; labroclypeus slightly asymmetrical; nasale prominent, with three strong teeth, lateral ones bifid; lateral lobes of epistome asymmetrical, rounded, shorter than nasale, margin with three or four setae projecting medially. Frontal sulci lyriform, reaching occipital foramen without fusing; coronal sulcus absent. Six stemmata on each side of head. Gular and cervical sclerites absent.

Antennae: Three-segmented, short. First segment slightly shorter than next two combined; second segment twice as long as third. Sensory appendage on second segment long, slightly shorter than third segment.

Mandibles: Symmetrical, with two inner teeth at midlength; distal tooth larger than basal one. No molar area developed.

Maxillae: Five-segmented. Stipes short, as long as palpifer, with a row of five stout setae on inner margin; palpifer long, slightly narrower than stipes, with a short apical galea. Palpi three-segmented; first and second segments subequal in length; third segment the shortest, two thirds as long as second segment.

Labium: Formed by submentum, mentum, and prementum. Submentum subpentagonal, rounded posteriorly. Mentum curved anteriorly, with four or five longitudinal rows of strong cuticular spines on dorsal surface. Prementum wider than mentum, pentagonal, laterally with several short setae. Palpi two-segmented, basal segment longer than second; ligula apparently segmented, subequal in length to labial palpi.

139 Thorax and legs: Pronotal plate large, covering most of prothorax, with sagittal line and one rounded lobe at midlength on each margin; prosternal plate large, subrectangular, with incomplete sagittal line on posterior half. Mesothorax wider than prothorax, anteriorly with four narrow transverse tergites, behind these a pair of large subrectangular tergites. Metathorax with two pairs of transverse tergites, anterior ones wider, subrectangular, posterior ones subtriangular. Legs five-segmented, visible in dorsal view.

Abdomen: Abdomen ten-segmented, segments nine and ten reduced. Segments one to seven similar in size and shape, subdivided into two or three transverse folds; anterior fold with eight tubercles, posterior fold with four small tubercles; all tubercles covered by asperities; pleurites strongly lobed. Segment eight with a subquadrate dorsal plate; segment nine slightly trilobed, with a pair of short one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With two pairs of supraorbital styli. Thorax: Pronotum with 24 styli, 20 on margins, four in a transverse row on disc. Mesonotum with one stylus on each side of scutellum; metanotum with one pair of styli near midline. Abdomen: Segments one to seven with four styli on tergal area; segments two to seven with one stylus on each pleurite. Segment eight with one pair of styli; segment nine with a pair of cerci.

140 Number of species and distribution: Small genus, with only two described species, both from the Neotropical region (Chile). Spangler (1979) describes the third instar larva and pupa of C. lineatopunctatus.

Bionomics: The only information about the habitat of this genus is provided by Spangler (1974, 1979). Adults, a larva, and pupae were collected either from debris in logjams piled in midstream, or by turning rocks on a ridge near the shore line, in small spaces between roots of mosses and grasses. C. lineatopunctatus seems to overwinter in adult stage (Spangler 1979).

Additional comments: Cylorygmus is the only known member of the tribe Rigmodini from South America; all the other genera of this tribe are from the Australian region.

28- Phaenonotum Sharp (Figures 85-87)

Egg case: Flat, made of two layers of silk, first layer applied to substrate, second covering the eggs. Built on the underside of leaves of aquatic plants, or by the margins of bodies of water, under plant debris, very close to the water’s edge. Two to four eggs in each case. Second layer of silk very fine, eggs seen through it. No mast is present.

Larva: Head capsule: Subquadrate; labroclypeus symmetrical; nasale prominent, with one tooth that can be trifid; lateral lobes of epistome rounded, as long to slightly shorter than nasale. Frontal sulci irregularly V-shaped, coming together towards occipital margin

141 without fusing (third instar larvae); coronal sulcus absent in third instars, present in first instars, very short. Six stemmata on each side of head, grouped tightly in third instar larvae. Gular sclerite absent; cervical sclerites present, subtriangular.

Antennae: Three-segmented, short. First segment wide, as long as two other combined (3rd instar larvae), slightly longer in first and second instar larvae; second segment carrying a stout sensory appendage as long as third antennal segment.

Mandibles: Symmetrical, with two inner teeth at midlength; distal inner tooth slightly larger than basal one. Inner margin of distal part of mandible serrated; distal tooth partly to completely serrated; inner margin of basal tooth also serrated. No molar area developed.

Maxillae: Five-segmented; cardo small, subtriangular. Stipes stout, twice as long as remaining segments combined, narrowing towards distal end, with a row of 10 to 14 strong setae on inner margin; palpifer short, wider than long, carrying a small, slightly sclerotized apical galea. Palpi three-segmented, first two segments short, wider than long; third segment as long as other two combined.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subtriangular; mentum subquadrate, may be constricted at base, with or without cuticular spines on dorsal surface; prementum subquadrate, smaller than mentum. Palpi two-segmented, second segment twice as long as first; ligula present, as long as second palpal segment, flat long spines may be present on membranes between prementum and palpi, and between palpal segments.

142 Thorax and legs: Prothorax strongly sclerotized, slightly wider on posterior margin, sagittal line present; prostemal sclerite large, subrectangular, with sagittal line complete or restricted to posterior half. Mesothorax and metathorax short, with a pair of sclerotized tergites. Legs five-segmented, short but well developed, visible in dorsal view.

Abdomen: Ten-segmented, segments nine and ten reduced. Segment one with a pair of narrow dorsal plates; segments one to seven similar in shape and size, subdivided into three transversal folds; pleurites slightly lobed. Segment eight with one dorsal plate, which can be subdivided; segment nine trilobed, with three small dorsal plates, carrying a pair of short one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With two pairs of supraorbital styli. Thorax: Pronotum with variable number of styli, between 20 and 26, 20 on margins and a transverse row of two to six on disc (intraspecific variation); mesonotum with one stylus on each side of scutellum; metanotum with one pair near midline. Abdomen: Segment one with four styli on tergum; segments two to seven with six styli on tergum and one stylus on each pleural area. Segment eight without styli; segment nine with a pair of very short cerci.

143 Number of species and distribution: Phaenonotum is a New World genus, with about 20 described species. Most of its members are Neotropical, with only two species in the Nearctic region. Archangelsky & Durand (1992c) described the immatures of Ph. exstriatum; Archangelsky & Femdndez (1994) describe the egg case and larval stages of Phaenonotum puncticolle (= Hydroglobus puncticolle).

Bionomics: Detailed information on the life cycle and biology of Phaenonotum is presented in the two papers mentioned above. Adults are aquatic or semiaquatic, living on a variety of habitats such as floating or aquatic vegetation, among the plant debris at the margins of bodies of water, and also some species have been reported from phytotelmata, usually inbromeliads (d’Orchymont 1937, Frank 1983, Archangelsky & Durand 1992c). The eggs are laid on the aquatic vegetation or on the debris at the edge of the water; females can lay several egg cases during the mating season; six females of Ph. exstriatum reared in laboratory laid between ten and 15 egg cases every week for about two months. Larvae hatch after five or eight days, they are predatory and also cannibalistic. Development of the larvae is fast, taking between 15 and 20 days. Prepupal stage is about two days, and pupation occurs in a pupal chamber dug in the soil, near the water. The pupal stage is short, two to three days, and adults remain in the cell for about one day before emerging. In mild climates larvae and adults can be found all year round (Archangelsky & Ferndndez 1994), and at least Ph. puncticolle is a bivoltine species, having two well defined recruitment periods during the year.

Additional comments: Phaenonotum in this dissertation is used in a wider sense than Hansen (1991); it includes Hydroglobus as a subgenus, therefore subdividing this genus in two subgenera: Ph. (Phaenonotum), and Ph. (Hydroglobus). Hydroglobus was originally created by Knish (1921) to include a single species described by Bruch

144 (1915) as Ph. puncticolle. Hansen (1991) in his generic revision of the Hydrophiloidea kept Hydroglobus and Phaenonotum as different genera; at the same time I had a paper in press downgrading Hydroglobus to a subgenus of Phaenonotum (Archangelsky 1992) based on the similarity in the male genitalia; later, the information gathered from larval characters seemed to support their congeneric relationship (Archangelsky & Femdndez 1994).

29- Dactylostemum A Wollaston (Figures 88-90)

Egg case: Flat, subcircular, made of two silk layers; first layer thin, white, applied on substrate; second layer thicker, brownish, covering the eggs. No mast present. Number of eggs usually four, laid side by side.

Larva: Head capsule: Suboval, labroclypeus asymmetrical; nasale short, with one median tooth; lateral lobes of epistome rounded, projecting as far as nasale (third instar larvae), larger and projecting further than nasale (first instar larvae). Frontal sulci fusing before reaching occipital foramen; coronal sulcus short, inconspicuous. Six stemmata on each side of head. Gular sclerite absent; cervical sclerites present, irregularly subtriangular.

Antennae: Three-segmented. First segment slightly shorter than other two combined (third instars), as long as second segment (first instars); apical sensory appendage of second segment one third the length of last antennal segment (third instars), half the length (first instars).

145 Mandibles: Strongly asymmetrical. Right mandible slightly smaller, with two small inner teeth at midlength, ventral one flat and sharp, dorsal one conical and blunt; left mandible with two small inner teeth in basal half, projecting backwards; middle inner margin of mandible pubescent. Distal inner margin of both mandibles serrated.

Maxillae: Five-segmented; cardo small, subtriangular. Stipes stout, longer than remaining segments combined, inner margin with a row of 19 strong setae; both inner and outer margins pubescent; palpifer short, subquadrate, pubescent on inner margin, carrying a short apical galea. Palpi three-segmented, basal segment subquadrate; second segment the shortest, wider than long; third segment as long as first.

Labium: Formed by submentum, mentum, and prementum. Submentum small, subtrapezoidal; mentum wider than long, with anterior and posterior margins concave; anterior margin covered by dense pubescence; prementum subrectangular, with dense pubescence at base of palps. Palpi two-segmented, basal segment slightly shorter than distal one; ligula reduced, absent. Hypopharynx asymmetrical, well developed on left side as a long subtriangular pubescent lobe, reaching the first palpal segment; base of hypopharynx connected to prepharynx which extends backwards almost to base of tentorium.

Thorax and legs: Pronotal shield well developed, covering most of pronotum, sagittal line present; prostemal plate subrectangular, with incomplete sagittal line on posterior third. Mesonotum with a large subrectangular plate, subdivided by a sagittal line; metanotum with two smaller subrectangular plates. Legs five-segmented, short but well developed, not seen in dorsal view.

146 Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in shape and size, subdivided into two transverse folds, anterior one larger than posterior one; segments one with a pair of small anterior oval plates, segments two to seven without sclerotized areas. Segments one to seven with two dorsal and two ventral rows of strong spines, used as aid in locomotion. Segment eight smaller, with a large suboval tergite; segment nine trilobed, with three small dorsal plates, carrying a pair of short one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Styli on head, thorax, and pleural areas of abdomen sclerotized, with yellowish to light brown pigmentation, and with rounded apex. Head: With two pairs of supraorbital styli. Thorax: Pronotum with 24 styli, 20 on margins and four on disc; mesonotum with one stylus on each side or scutellum; metanotum with one pair of styli between midline and base of wingpads. Abdomen: Segment one with four pairs of small styli on dorsal side of segment, and two large styli on each lateral margin; segments two to seven each with four pairs of small styli on dorsal side (two anterior and two posterior), two larger pairs on each lateral margin, and one large stylus on each pleurite. Segment eight with three pairs of small styli, and one pair of larger styli; segment nine carrying a short pair of cerci, with a small sclerotized apical process.

147 Number of species and distribution: This is a rather large genus, with 65 to 80 described species worldwide (Smetana 1978, Newton 1989, Hansen 1991). Most of the species are tropical or subtropical; there are about 25 described species from the New World, most of them Neotropical. The third instar larva of D. subrotundum has been described by Costa et al (1988), in this revision the larva of D. subrotundum is included within the Dactylostemum B type of larvae; the immatures of D. cacti were described by Archangelsky (1994a).

Bionomics: Detailed information on the biology of D. cacti is provided in Archangelsky (1994). Both adults and larvae of Dactylostemum occur on a variety of decaying organic matter, either animal or vegetable. Adults of D. cacti feed on rotting cactus, burrowing within the decaying tissues. The eggs are laid in this same substrate, egg cases usually have four eggs. Larvae hatch after four to six days, and larval development is quite fast, about 20 days; duration of first and second instars is short, two to four days each; larvae are predatory, feeding on the numerous fly larvae found in these habitats, they are also cannibalistic; larvae tend to be greenish in color. Prepupae are active for a few days, they prefer drier parts of the cactus, and they build a pupal chamber by chewing tissues of the cactus. Adults emerge after five days. Some species of Dactylostemum have been introduced as biological control agents: three species have been used to control sugar cane beetle borers in the Philippines and Hawaii; one species has been used to control banana borers in Jamaica (Leech & Chandler 1956, Spangler 1989).

Additional comments: Costa et al (1988) described a larva found in association with adults of D. subrotundum', they considered this the larva of D. subrotundum. Archangelsky (1994a) reared and described the immatures of D. cacti, finding major

148 differences between the larva of D. subrotundum and D. cacti. At that time I argued that due to those differences: 1- the association between the adults of D. subrotundum and that larva may have been incorrect; or 2- D. cacti and D. subrotundum were not congeneric, and if that was the case, implying that a revision of the genus Dactylostemum should be necessary. More recently in a trip to Venezuela (National Park Henri Pittier) I collected and reared two species of Dactylostemum, one of them had larvae resembling those of D. cacti; the other had larvae resembling those of D. subrotundum, therefore confirming the association made by Costa et al (1988). These results strongly support the necessity of a generic revision of Dactylostemum which, from the larval point of view, seems to be polyphyletic, being formed of at least two different genera. The description of this other species of Dactylostemum follows as Dactylostemum B.

30- Dactylostemum B Wollaston (Figures 91-93)

Egg case: Oval, bottom layer as a shallow cup on the substrate; top layer flat, opaque, covering the eggs. No mast. Five to six eggs in each case.

Larva: Head capsule: Suboval, wider at the base. Labroclypeus asymmetrical; nasale short, trifid; lateral lobes of epistome asymmetrical, right one rounded, left one with spines and setae projecting mediad. Frontal sulci fusing before reaching occipital foramen; coronal sulcus present, short. Six stemmata closely grouped, but still distinguishable, on each side of head. Gular sclerite absent; cervical sclerites present, suboval.

149 Antennae: Three-segmented. First segment as long as remaining two combined (third instars), shorter than other two combined (first instars). Second segment twice as long as third, carrying a sensory appendage shorter than third segment (third instar), as long as third segment (first instars).

Mandibles: Slightly asymmetrical, both with two inner teeth irregularly shaped. Right mandible with distal inner margin slightly serrated; left mandible with inner margin more extensively serrated.

Maxillae: Five-segmented. Cardo small, subtriangular. Stipes longer than remaining segments combined, with outer basal margin densely pubescent; inner margin with a row of 12 stout setae; palpifer short, subquadrate, poorly sclerotized in some areas, carrying a short apical galea. Palpi three-segmented, basal two segments subquadrate; apical segment more elongate.

Labium: Formed by submentum, mentum, and prementum. Submentum subtriangular; mentum slightly wider than prementum, dorsal surface with strong cuticular spines projecting forward; prementum subquadrate, with several fine spines at the base of palpi. Palpi two-segmented, distal segment twice as long as basal one; several fine spines on intersegmental membrane, ligula present, as long as basal palpal segment, strongly sclerotized. Hypopharyngeal lobe present, asymmetrical, developed on left side as a short pubescent subtriangular lobe; reaching base of prementum.

Thorax and legs: Pronotal shield well developed, covering most of prothorax, sagittal line present; prostemal plate subrectangular, with incomplete sagittal line on basal fourth. Mesonotum with two pairs of sclerites, anterior one small, subtriangular,

150 posterior one large subrectangular, subdivided by a sagittal line; metanotum with a small irregular plate, subdivided by a sagittal line. Legs five-segmented, short but well developed, not visible in dorsal view.

Abdomen: Ten segmented, segments nine and ten reduced. Segment one with two pairs of small, transverse plates. Segments one to seven similar in size and shape, subdivided by two transverse folds; sternal area of each segment with two transverse rows of strong spines. Segment eight smaller, with a large suboval tergite; segment nine trilobed, with three small dorsal plates, carrying a pair of short one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Unknown.

Number of species and distribution: See Dactylostemum A.

Bionomics: The adults used for this study were collected at the base of rotting leaves (still attached to the plant) of Araceae plants in the cloud forest of Venezuela (National Park Henri Pittier). The adults dwell in the decaying tissues of the plant, feeding on these tissues. Eggs are laid on this substrate; first instar larvae hatch after eight to ten days. Larval development is fast, three to four days for first and second instar larvae, and eight to ten days for third instars. They feed on a variety of fly larvae found in this habitat, they are also cannibalistic. Pupation was not observed.

151 Additional comments: See Dactylostemum A.

31- Cercyon Leach (Figures 94-96)

Egg case: Egg cases laid on the same substrate were adults and larvae live. Made of two silk layers; bottom one forming a shallow cup adhering to the substrate; top one flat, covering the eggs, translucent. No mast present. Number of eggs varies from four to eight.

Larva: Head capsule: suboval, slightly longer than wide. Labroclypeus asymmetrical, right side flat, with glabrous margin, left side with a small concavity, covered by a fringe of short hairs; lateral lobes of epistome rounded, shorter than nasale. Frontal sulci lyriform, reaching occipital foramen without fusing, difficult to see in third instar larvae; coronal sulcus absent. Stemmata on dorsal side of head, closely aggregated. Gular sclerite absent; cervical sclerites present, small, suboval.

Antennae: Three-segmented, short. First segment longer than remaining two combined; second segment the shortest, subquadrate, carrying a long sensory appendage; third segment as long or slightly longer than sensory appendage.

Mandibles: Strongly asymmetrical; right mandible carrying an inner tooth at midlength, distal inner margin of mandible serrated; left mandible lacking teeth, crenulated or strongly serrated at base, distal inner margin serrated or smooth.

152 Maxillae: Five-segmented; cardo small, subtriangular. Stipes strong, as long as remaining segments combined, with a row of seven to 12 strong setae on inner margin, densely pubescent; palpifer short, subquadrate, apical galea small, reduced to a poorly developed bump, unsclerotized. Palpi three-segmented, tapering towards apex, all three segments subequal in length.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subtriangular, much wider than mentum; mentum short, subrectangular, wider than long; prementum very small, mostly membranous, reduced to a small plate that can carry one or two pairs of setae. Palpi two-segmented, both segments subequal in length; ligula reduced, not visible. Hypopharynx well developed on left side, subtriangular, densely pubescent, reaching farther than labial palps.

Thorax and legs: Pronotal shield large, covering most of dorsal surface of prothorax, sagittal line present; prosternum with a narrow irregular plate, sagittal line absent. Mesonotum with a rather large subrectangular plate, sagittal line present; metanotum with two smaller, narrow subtriangular plates, separated by a sagittal line. Legs extremely reduced, three-segmented, sometimes difficult to see, coxae poorly sclerotized.

Abdomen: Ten segmented, segments nine and ten reduced. Segments one to seven similar in shape and size, without sclerites, subdivided into two transversal folds. Eight segment with a large suboval tergite, with posterior margin variously lobed; segment nine trilobed, carrying a pair of small one-segmented urogomphi.

153 Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With two pairs of well developed supraorbital styli. Thorax: Pronotum with 18 to 20 styli, 18 on margins, and, when 20, two on disc. Mesonotum with one stylus on each side of scutellum; metastemum with one pair of styli near midline. Abdomen: Segments one to seven with a transverse row or four styli on tergum, two near midline and two near margins; pleurites two to seven each with one stylus. Segment eight without styli; segment nine carrying a pair of short cerci ending in long filaments.

Number of species and distribution: This is a large genus, with about 190 described species. Cercyon is abundant in the Nearctic, Palaearctic, Ethiopian and Oriental regions; a few species have been described from the northern Neotropical and Australian regions. Many species associated with dung have been introduced to the New World from the Palaearctic region; about 55 species have been described or reported from the New World. There are several references and descriptions of Cercyon immatures: Thomson (1860) describes the larva of C. littoralis; Schiodte (1861-1872) describes C. analis and redescribes C. littoralis; Bpving & Henriksen (1938) redescribe both species; Hafez (1939b) describes the larva of C. quisquilius; Quennedey (1965) does a detailed comparative study of an unidentified Cercyon larva with those of Sphaeridium scarabaeoides and Megasternum obscurum (= M. boletophagum); Schulte (1985) compares the larvae of six Palaearctic species inhabiting

154 dung (C. haemorrhoidalis, C. unipunctatus, C. quisquilius, C. pygmaeus, C. lateralis, and C. melanocephalus) of which the first five have been introduced into the New World (Nearctic region).

Bionomics: Members of this genus live in a variety of terrestrial and semiaquatic habitats, usually in different kinds of decaying organic matter, including dung, decaying seaweed or algae in littoral zones, rotting plant material and mushrooms, carrion, sap, etc. Most of the ecological information on Cercyon deals with those species inhabiting dung: Sanders & Dobson (1966), McDaniel etal. (1968), Kessler etal (1972), Hanski (1980a, 1980b, 1979), Schulte (1985), Hanski & Cambefort (1991), Dobe & Wardhaugh (1991), etc. Females lay small egg cases on the same substrate on which they feed, the number of eggs varying among the species, between four and eight. Females can lay several egg cases during their life cycle, and there can be two or more generations within the same year, even in temperate climates. Larvae hatch after two or three days, they are predatory and also cannibalistic, their main prey being dipteran larvae that cohabitate those habitats. Larval developmental time is short, ten to twelve days from first instar to pupal stage, including prepupal period (personal observation); this rapid development favors the inhabitation of ephemeral habitats such as dung, decaying mushrooms, etc. Pupation takes place in small pupal chambers dug in soil or in the substrate on which they live.

32- Pelosoma Mulsant (Figures 97-99)

Egg cases: Suboval, laid on the substrate were adults live; made of two layers of silk, first one oval, applied over the substrate, second one covering the eggs, thick, extending

155 into a long mast, two to four times the length of the case. About four eggs in each case.

Larva: Head capsule: Subquadrate; labroclypeus asymmetrical, nasale short and wide, convex, with a small pubescent notch on left side; lateral lobes of epistome rounded, shorter than nasale. Frontal sulci lyriform, converging before reaching occipital foramen, difficult to see in third instar larvae; coronal sulcus absent. Stemmata closely aggregated. Gular sclerite absent; cervical sclerites present, small, suboval, difficult to see on first instar larvae.

Antennae: Three-segmented. First segment wider and slightly longer than next two combined; second segment twice as long as third segment, carrying a long sensory appendage, as long as third segment.

Mandibles: Strongly asymmetrical; right one with a large inner tooth on distal half; inner margin of mandible slightly grooved; distal inner margin finely serrated. Left mandible without defined inner teeth; inner margin serrated from base to apex, serration on basal third coarser.

Maxillae: Five-segmented; cardo subtriangular. Stipes stout, longer than remaining segments combined, with a mesal row of nine strong setae; inner and dorsal surface densely pubescent; palpifer subquadrate, short, dorsal surface with minute, blunt cuticular projections, apical galea reduced, unsclerotized. Palpi three-segmented, tapering towards apex, first and third segments subequal in length, second segment slightly shorter; first and second dorsally with minute cuticular projections. First instar larvae with pubescence on stipes, without cuticular projections on palpifer and palpal

156 segments.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subpentagonal; mentum short, subrectangular, wider than long; prementum small, reduced to a narrow, subdivided transverse plate on ventral side. Palpi two-segmented, both segments subequal in length; ligula absent. Hypopharyngeal lobe large, developed on left side, projecting farther than labial palpi.

Thorax and legs: Pronotal shield large, covering most of prothorax, with sagittal line; prosternal plate large, irregularly shaped. Mesonotum with a large, narrow, subrectangular plate, subdivided by a sagittal line; metanotum with a pair of narrow, transverse subtriangular tergites. Legs reduced, three-segmented, coxae membranous, similar to those of Cercyon.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in shape, without tubercles or sclerites, subdivided into two transversal folds. Segment eight with a large, subquadrangular tergite, with posterior margin almost straight; segment nine trilobed, carrying a pair of one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, functional but smaller than those in other genera, within the spiracular atrium.

Pupa: Head: With two pairs of long supraorbital styli.

157 Thorax: Pronotum with 20 styli, 18 on the margins and one pair on disc. Mesonotum with one pair close to the scutellum; metanotum with one stylus close to the base of each wingpad. Abdomen: Tergites one to seven with a transverse row of four styli, segments two to seven with one stylus on each pleura. Segment eight without styli; segment nine with a pair of cerci ending in long filaments.

Number of species and distribution: Small genus, with 19 described species, most of them from the Neotropical and southern Nearctic regions; there are a few species in the Ethiopian, Oriental, and Australian regions. This is the first description of the immature stages for this genus.

Bionomics: Little is known about this genus. The only Nearctic species occurs in decaying organic matter, and is common in rotting cacti such as Cereus sp., I had the opportunity of collecting some specimens in Arizona in that habitat. The larvae described here were collected in Venezuela, from Heliconia sp. flowers, which collect water from the rain; the adults were found in mature flowers and the eggs were laid at the base of the flowers, sometimes in groups of five to ten cases. Larvae hatched after four or five days, and the developmental time was short, 25 to 35 days. Larvae are predatory, feeding on a variety of fly and mosquito larvae that inhabit these phytotelmata, they are also cannibalistic. In laboratory pupation took place in a cell made of chewed tissue paper, suggesting that in nature they could do the same by chewing plant tissues.

Additional comments: Larvae of Pelosoma are very similar to those of Cercyon, and it is very difficult to tell them apart, the most evident difference seems to be in the shape

158 of the tergal plate of the abdominal segment eight (mentioned in the key), but this is based on only one species of Pelosoma, and this character may vary in other species.

33- Cryptopleurum Mulsant (Figures 100-102)

Egg cases: Laid in small cracks or depressions in the dung; cases made of two layers, first one cup-shaped, second one flat, covering the eggs; no mast is present. Number of eggs four to eight.

Larva: Head capsule: Suboval, occipital foramen large; labroclypeus asymmetrical; nasale well developed, with a small concavity on left side, margined by a fringe of short hairs; lateral lobes of epistome rounded, much shorter than nasale. Frontal sulci originating on sides of antennae, coming together and then slightly diverging on basal third, reaching occipital foramen widely separated, difficult to see in second and third instar larvae, well defined on first instar larvae; coronal sulcus absent. Stemmata closely aggregated. Gular sclerite absent; cervical sclerites small, suboval.

Antennae: Three-segmented. First segment wider, as long as remaining two segments combined in first instar larvae; longer in third instar larvae; second segment subquadrate, slightly shorter than third (longer in first instar larvae), carrying a very long sensory appendage, as long as third antennal segment.

Mandibles: Strongly asymmetrical. Right mandible slightly smaller, with an inner tooth on distal half, sickle-shaped, pointing backwards, smooth on first and second instar

159 larvae, irregularly serrated on third instars; distal inner margin poorly serrated. Left mandible without inner teeth, inner margin serrated, poorly at distal end, more strongly serrated at base.

Maxillae: Five-segmented; cardo small, subtriangular. Stipes large, slightly longer than remaining segments combined, outer margin convex, inner margin straight, with a row of six stout setae; outer margin pubescent. Palpifer short, subquadrate, with dorsal surface covered by minute cuticular spines; apical galea reduced to a small, poorly sclerotized lobe. Palpi three-segmented, first and second segments short, subequal in length; third segment the longest, bare; first segment with few minute spines on dorsal surface.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subtriangular; mentum narrower, subrectangular, wider than long; prementum reduced to a narrow transverse plate on ventral side. Palpi two-segmented, both segments subequal in length. Hypopharyngeal lobe large, developed on left side, projecting farther than labial palpi.

Thorax and legs: Pronotum covering two anterior thirds of prothorax, with sagittal line; prosternal plate large, subtrapezoidal, without sagittal line. Mesonotum large, subrectangular, with sagittal line; metanotum much smaller, narrow, subrectangular, with sagittal line. Legs absent, reduced to a small lobe with a few spines.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in shape and size, subdivided into two transverse folds, without any tubercles or plates; pleural areas poorly lobed. Segment eight with a large subcircular tergal plate,

160 posterior margin with three to five small lobes; segment nine small, almost completely covered by segment eight, trilobed, carrying a pair of small one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, functional but smaller than those in other genera, within the spiracular atrium.

Pupa: Head: With two pairs of long supraorbital styli. Thorax: Pronotum with 18 styli, 16 on margins and one pair on disc. Mesonotum with one pair of styli close to scutellum; metanotum with one stylus close to base of wingpads. Abdomen: Segments one to seven with a transverse row of four styli on tergal areas; segments two to seven with one stylus on each pleura. Segment eight without styli; segment nine carrying a pair of cerci, each one ending in a short filament.

Number of species and distribution: Relatively small genus, with 21 described species; it is known from all the biogeographic regions except from South America. There are seven species in the New World, six of them from the Nearctic region, only two are found in Mexico and Central America.

Bionomics: Species belonging to this genus are common in different terrestrial, and sometimes semiaquatic habitats, such as dung, compost piles, rotting cactus, in moss near water, etc. Females lay eggs on the same substrate where they live, and the eggs hatch after two or three days. Larval development is fast, averaging two weeks, including the prepupal stage. Pupation takes place in the soil, or in some cases (under

161 laboratory conditions) the prepupae can build the pupal chamber by chewing tissue paper (like the larvae of Dactylostemum cacti). Larvae are predatory, and also cannibalistic, feeding on fly larvae that live in the same habitats.

Additional comments: Of the seven known New World species of Cryptopleurum, three have been introduced from the Palaearctic region. Bpving & Henriksen (1938) described a larva which they referred to as “ Cryptopleurum or Megastemum” (pags. 100-102); at the end of their revision of the Danish immature hydrophilids (pag. 159), they add a note stating that their previous description (pags. 100-102) must refer to Megastemum, due to recent information received from someone else that had reared Cryptopleurum minutum F. After that paper, no one has published any description of the immatures of Cryptopleurum, making this is the first description of the immature stages of this genus.

34- Pemelus Horn (Figures 103-105)

Egg case: Small, cup-shaped, laid on the same substrate were adults live. Made of two layers, bottom one concave, top one covering the eggs. No mast present. Two to six eggs in each case.

Larva: Head capsule: Suboval, wider at basal third; labroclypeus asymmetrical, right side flat, left side notched, covered by a fine pubescence; lateral lobes of epistome rounded, shorter than nasale. Frontal sulci lyriform, reaching occipital foramen widely apart; coronal sulcus absent. Stemmata closely aggregated. Cervical sclerites narrow,

162 transverse; gular sclerite absent.

Antennae: Three-segmented. Basal segment as long as remaining two combined; second and third segments subequal in length, second segment carrying a sensory appendage half the length of third segment (as long as third segment in first instar larvae).

Mandibles: Asymmetrical; right mandible with an inner tooth on distal half, apex of tooth serrated in third instar larvae, smooth in first instars; left mandible without inner teeth, mesal margin serrated.

Maxillae five-segmented, cardo small, subtriangular. Stipes stout, as long as remaining segments combined, with a row of nine strong setae on inner margin, outer margin with numerous flat, long spines, inner margin pubescent; palpifer subquadrate, with dorsal surface covered by small cuticular spines. Palpi three-segmented, second segment the shortest; dorsal surface of first and second segments with several minute spines.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subtriangular, wider than remaining segments; mentum subrectangular, wider than long; prementum reduced to a small, narrow plate on ventral side. Palpi two- segmented, basal segment longer than second; ligula reduced, absent. Hypopharyngeal lobe large, developed on left side, densely pubescent, projecting farther than labial palps.

163 Thorax and legs: Pronotal shield large, with sagittal line; prostemum irregularly shaped, narrow, without sagittal line, mesonotum with a large subrectangular plate, subdivided by a sagittal line; metanotum with two narrow, transverse plates. Legs extremely reduced, two-segmented (coxae membranous).

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in size and shape, lacking sclerites, subdivided into two transversal folds; pleural areas slightly lobed. Segment eight with a large suboval tergite, posterior margin with three small lobes; segment nine trilobed, carrying a pair of short, one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With two pairs of long supraorbital styli. Thorax: Pronotum with 20 styli, 18 on margins, a pair on disc. Mesonotum with one pair of styli near scutellum; metanotum with one stylus close to each wingpad. Abdomen: Segments one to seven with a transverse row of four styli on tergal areas; segments two to seven each with a stylus on each pleura. Segment eight without styli; segment nine with a pair of cerci, each ending in a long filament.

Number of species and distribution: Small genus, with two known species (Malcolm 1981, Hansen 1991); both species from the New World: P sculptum from Argentina, and P. costatus from the eastern Nearctic region. This is the first description of the

164 immature stages of this genus.

Bionomics: Not much is known about this genus. P. sculptum was described by Bruch (1915) from a series of specimens collected in rotting tomatoes; P. costatus has been reported from a variety of decaying organic matter such as meat traps, under dog carcasses, dung, and litter at tree bases (Smetana 1978). I have collected P. costatus with flight intercept traps, and with pig dung traps, mixed with fermenting malt. Adults lay eggs on the dung (used as a substrate to rear them in laboratory), and larvae hatch after three to five days. Development of the larvae is fast, two to three days for first and second instars, and five to six days for third instars. Larvae are predatory, feeding on fly eggs and larvae, they are also cannibalistic. Pupation took place under tissue paper, in nature they probably pupate in soil.

Additional comments: The legs of these larvae seem to be an intermediate stage of reduction between those of Cryptopleurum (almost completely lost), and those of Cercyon and Pelosoma (three-segmented, with a membranous or poorly sclerotized coxa). Besides that character, the only way to tell apart a larva of Pemelus is by the flat spines on the outer margin of the stipes (present in all the instars).

35- Megastemum Mulsant (Figures 106-107)

Egg case: Unknown.

165 Larva: Head capsule: Suboval, occipital foramen large. Labroclypeus asymmetrical; nasale broad, irregular,right side flat, leftside with a small concavity margined by a fringe of short and fine hairs; lateral lobes of epistome rounded, shorter than nasale. Frontal sulci parallel, slightly diverging on basal third, reaching occipital foramen widely separated; coronal sulcus absent. Six stemmata on dorsal side of head, closely aggregated. Gular sclerite absent; cervical sclerites small, suboval.

Antennae: Three-segmented, short. First segment longer than two remaining segments combined; second segment subquadrate, carrying a long sensory appendage, slightly shorter than third antennal segment.

Mandibles: Strongly asymmetrical. Right mandible slightly smaller, with a large inner tooth at midlength, irregularly serrated along margins; left mandible without inner teeth, roughly serrated along inner margin, middle denticles larger.

Maxillae: Five-segmented; cardo small, subtriangular. Stipes wide and longer than remaining segments combined, outer margin convex, inner margin straight, with a row of nine strong setae, inner and outer margins pubescent; palpifer subquadrate, with apical galea reduced to a small poorly sclerotized lobe. Palpi three-segmented, all three segments subequal in length, tapering towards apex.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subpentagonal; mentum small, subtriangular, wider than long; prementum small, narrow, reduced to two small, ventral plates separated by a narrow sagittal line. Palpi two-segmented, short, basal segment slightly shorter than second; ligula absent.

166 Thorax and legs: Pronotal shield large, covering most of pronotum, sagittal line present; prostemal plate large, irregularly subtriangular, without sagittal line, mesonotum with a large tergite, subrectangular, with a narrow sagittal line; metanotum narrow, also with sagittal line, each side narrowly subtriangular. Pleural areas of meso- and metathorax lobed. Legs reduced, three-segmented, like those of Cercyon.

Abdomen: Ten-segmented, segments nine and ten reduced. Segments one to seven similar in shape and size, subdivided into two or three transversal folds, without dorsal plates or tubercles; pleural areas strongly lobed. Segment eight with a large suboval tergite, posterior margin trilobed; segment nine almost completely covered by eighth segment, trilobed, with a small pair of one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Unknown.

Number of species and distribution: Megastemum is a small genus, with six described species, all from the Nearctic and Palaearctic regions. In the Nearctic region there are three species, of which one, M. obscurum (= M. boletophagum) has been introduced from the Old World. The larva of M. obscurum has been described by Phillips (1923) and latter by Bpving & Henriksen (1938) (see additional comments on Cryptopleurum) and Quennedey (1965).

167 Bionomics: Not much is known about the biology and ecology of this genus. Both adults and larvae are terrestrial, and occur in different kinds of decaying organic matter (both in open and wooded areas), such as rotting mushrooms compost piles, carrion, moss, dung, etc. From the structure of the mouthparts (similar to those of other known Megastemini) it can be said that the larvae are predatory, probably feeding on fly larvae found in those habitats.

36- Sphaeridium Fabricius (Figures 108-111)

Egg case: Laid in dung or other kinds of decaying organic matter; case made of two layers, first one cup-shaped, in which the eggs are laid; second one flat, covering the eggs, thin, translucent. No mast is present, number of eggs unknown.

Larva: Head capsule: Subcircular; labroclypeus asymmetrical; nasale broad, irregularly shaped, with three pointed lobes, left one covered by a fine pubescence; lateral lobes of epistome small, slightly lobed, shorter than nasale. Frontal sulci lyriform, reaching the occipital foramen widely separated; coronal sulcus absent. Six stemmata on dorsal side of head, closely aggregated in two groups, hind one reduced. Gular sclerite absent; cervical sclerites present, suboval.

Antennae: Three-segmented, short. First segment slightly longer than remaining ones combined; second and third segments subequal in length, third one narrower; sensory appendage of second segment short, one fourth the length of last segment.

168 Mandibles: Asymmetrical, with a grove on inner margin. Right mandible without inner teeth, partly serrated on inner margin; left mandible without inner teeth, serrated on inner margin, with fine pubescence at midlength.

Maxillae: Five-segmented; cardo small, subtriangular. Stipes broad, as long as remaining segments combined, outer margin convex, inner margin straight, with a row of 12 or 14 stout setae; palpifer subrectangular, incompletely sclerotized, slightly longer than wide, apical galea reduced, very small and unsclerotized. Palpi three-segmented, tapering towards apex; first segment slightly longer than second; second and third segments subequal in length. Palpifer and first palpal segment with minute cuticular spines on dorsal surface.

Labium: Formed by submentum, mentum, and prementum. Submentum large, subpentagonal; mentum small, subrectangular, wider than long; prementum smaller, subrectangular, sclerotized on both sides. Palpi two-segmented, first segment the shortest; ligula present, small, half the length of first palpal segment. Hypopharynx well developed, as a long subtriangular lobe on left side, covered by a fine pubescence, reaching apex of second palpal segment.

Thorax and legs: Pronotal shield covering most of dorsal surface of prothorax, sagittal line present; prosternum with a large plate, sagittal line absent. Mesostemum with a pair of large subrectangular sclerites, separated by a sagittal line; metanotum with a pair of smaller sclerites, with sagittal line and a transversal line at middle. Legs short, reduced, five-segmented, not visible in dorsal view.

169 Abdomen: Ten-segmented; segments nine and ten reduced. Segments one and two each with two pairs of small tergal plates, anterior one narrow and transverse, posterior one suboval, smaller on segment two. Segments one to seven similar in shape and size, subdivided into two transverse folds; pleural areas not lobed. Segment eight wide, with on pair of finger-like lobes on each lateral margin, tergal plate suboval, with posterior margin lobed; segment nine trilobed, completely covered by segment eight, carrying a pair of small one-segmented urogomphi.

Spiracles: Nine pairs; one mesothoracic and eight abdominal. Mesothoracic and first seven abdominal spiracles non-functional, biforous; spiracles on segment eight annular, large and functional, within the spiracular atrium.

Pupa: Head: With two pairs of long supraorbital styli. Thorax: Pronotum with 24 long styli, 20 on margins and four in a transverse row on disc. Mesonotum with one stylus on each side of scutellum; metanotum with one pair of styli near midline. Abdomen: Segments one to seven with a transverse row of four styli on dorsal side; pleurites two to seven each with one long stylus. Segment eight without styli; segment nine with a pair of short conical cerci, each ending in a long ribbon-like projection.

Number of species and distribution: Rather large genus, with 41 described species, world wide in distribution, but most of the species are from the Ethiopian and Oriental regions. Of the four New World species, three have been introduced from the Palaearctic region into the Nearctic region; the remaining species is Neotropical (Brazil). Egg cases, larvae and pupae of Sphaeridium scarabaeoides and S. bipustulatum have

170 been described by Schiodte (1861-1862), and B0ving & Henriksen (1938); Hafez (1939c) redescribes the larva and the pupa (briefly) of 5. scarabaeoides; Quennedey (1965) presents a detailed morphological study of the larva of S. scarabaeoides, comparing it to the larvae of Megastemum obscurum (= M. boletophagum) and Cercyon sp.

Bionomics: All the information available on the development of the immatures of this genus comes from the two common species: S. scarabaeoides, and S. bipustulatum. All species of this genus are terrestrial, living in different kinds of decaying organic matter and fresh mammal dung. The three species introduced from the Palaearctic region are usually found in dung from different domesticated animals, but sometimes they are attracted by decaying mushrooms, carrion, or other plant material; nothing is known about the habitat of the only Neotropical species (S. brasilense). Females lay egg cases similar to those of Cercyon and other , but larger in size. Larvae hatch in a few days and contrary to Hafez statements (1939c), they are predaceous, feeding on fly larvae, also cannibalistic; their development is short, about ten days (Hafez 1939c). Pupation occurs in the soil, or in the same substrate where they live, and it lasts three or four days.

171 CHAPTER 6 PHYLOGENETIC ANALYSIS OF HYDROPHILOIDEA

Current Phylogenetic Hypotheses

The relationships among families within the Hydrophiloidea is far from being resolved. The problems encompass which families should be included and the way those families are related to each other. The two most recent phylogenetic analyses of Hydrophiloidea are those by Hansen (1991), and Beutel (1994). These authors arrive at very different conclusions. Hansen, using adult characters and a few characters from immature specimens (a total of 176 characters) obtained nine equally parsimonious trees with 534 steps (Figure 112A). Applying a more relaxed parsimony, Hansen discarded those trees in favor of one a single step longer (535 steps) based on one aspect of larval morphology (Figure 112B). More precisely, he considered that the spiracular atrium could not have been an ancestral character for the hydrophiloids. The two trees obtained by Hansen group the families of hydrophiloids in a very different way. Unfortunately, this is in part because Hansen’s analysis includes imprecise and incomplete information from immature stages, because he was forced to rely on the bibliography to code the characters. As it is evident from redescriptions of larvae of some hydrophiloid families (i. e. Epimetopidae, Georissidae, and Hydrochidae) (Richmond 1920, van Emden 1956, Rocha 1967), the information in some of the original descriptions is either misleading or incomplete in several aspects. The relations among the families of Hydrophiloidea, from the 534- and 535-step trees, can be seen

172 better represented as unrooted trees (Figures 113A, B), and it is evident that there is little in common between both trees. Beutel’s analysis (1994) was based only on characters from the head of adults and larvae (39 characters in total), and his results (Figure 114 A) are extremely different from those of Hansen. Beutel’s hypothesis also included Hydraenidae as belonging to the Hydrophiloidea. He argued that some characters shared by Hydraenidae and Hydrophiloidea (sensu Hansen) are extremely specialized, and unlikely to evolve independently in both groups. It should be noted here that several of those characters are correlated with an aquatic way of life, so it would not be unexpected for them to have evolved independently (homoplasious). On the other hand, Beutel had no problem with a complex set of characters (associated with the development of the spiracular atrium and metapneustic condition) evolving once, being lost, and then evolving for a second time. Beutel’s results are represented as an unrooted tree in Figure 114B.

Phylogenetic Analysis

I present here two analyses. The first one based on both new and historical characters from the immature stages. The second one combines characters from immature stages with those of Hansen (1991) for the adult hydrophiloids; this approach is known as “total evidence” (Kluge 1989), and aspires to find cladograms supported by the combined weight of all present character data. Competing hypotheses are represented as unrooted trees to preserve the stepwise association of taxa for comparison, of course, outgroup comparison (Watrous & Wheeler 1981, Nixon & Carpenter 1993) is the final arbiter of character polarity.

173 For the first analysis 11 taxa and 44 characters were used, of those 35 were binary, and nine were multistate, non-additive (unordered). For the second analysis the matrix had 132 characters (35 from larvae and 97 from adults); the difference in number of characters from immature stages is due to the elimination of two outgroups (Silphidae and Histeridae); by doing this some of the characters became uninformative (characters 4, 5, 6, 15, 32, 40, 41, 42, and 44) . In the second analysis 125 characters were binary, and seven multistate (one from larvae, non-additive, and six from adults, additive). The list of characters (44 characters) and character states for the preimaginal stages is shown in Appendix A, and the data matrix for those taxa and characters in Appendix B. The matrix was analyzed using PAUP 3.0 (exhaustive search), Hennig86 (with m*bb* search), and P. Golobof s NONA (rs = 0, hold = 500, m* 30 search). The list of adult characters (97 characters) and character states is shown in Appendix C, the data matrix for those characters is presented in Appendix D; they were analyzed using the same software. Finally, Appendix E shows the data matrix used for the combined analysis (132 characters).

a- Analysis of Characters from Immatures

In this analysis, characters from the different stages are used (eggs, egg cases, larvae, and pupae). In order to polarize the characters, three outgroups were used: Silphidae (Nicrophorus), Hydraenidae ( Ochthebius ), and Histeridae ( Onthophilus). The three outgroups belong to the series Staphyliniformia (Lawrence & Newton 1982, Newton & Thayer 1992); the first two are staphylinoids, and the third one is considered here as an histeroid. Larvae and pupae of Nicrophorus and larvae of Ochthebius were

174 examined (all from specimens reared in laboratory); information on pupae of Ochthebius was obtained from Bpving & Henriksen (1938). Information on Onthophilus and Histeridae was obtained from Newton (1991), Kovarik & Passoa (1993), and Kovarik (1994). The ingroups of the analysis are the six families of Hydrophiloidea; Hydrophilidae, due to its diversity, is represented by two tribes and one subtribe (Sperchopsini, Megastemini, Hydrophilina). The analysis with immatures yields some interesting results. In the first place only two trees result from the exhaustive search (Figure 115A, B), but the relations at the family level do not differ (the only difference between trees is the grouping of three tribes and subtribe of hydrophilids). Those trees are represented as an unrooted tree (Figure 116); they agree to some degree with Hansen’s 534-step tree (Figure 113A), both trees have two clades in common, one formed by Spercheidae + Hydrochidae + Hydrophilidae, and the other by Epimetopidae + Georissidae + Helophoridae. There is no similarity with Hansen’s 535-step tree (Figure 113B), and none with that of Beutel (Figure 114B).

b- Analysis of Characters from Adults and Immatures

For this analysis two of the outgroups (Silphidae and Histeridae) had to be eliminated, since the only outgroup in common with Hansen’s analysis were the hydraenids. By doing this, some of the characters became uninformative, and were removed from the analysis (add #). The combined matrix produced only one tree (Figure 117A), which differs from the one obtained with only immature characters (Figure 115 A), but is consistent in the two original groupings or clades obtained in the first analysis: Helophoridae +

175 Epimetopidae + Georissidae form one cluster, while Hydrochidae + Spercheidae + Hydrophilidae form another cluster. These results are represented as an unrooted tree in Figure 117B).

Discussion

a- Position of Hydraenidae: Traditionally, hydraenids have been included within the hydrophiloids, sometimes as a family, other times as a subfamily. Bpving & Craighead (1931), and Dybas (1976), based on larval characters, proposed the transfer of Hydraenidae into the Staphylinoidea. Later Bpving & Henriksen (1938) include them within the Hydrophilidae, but with reservations “...the habitual appearance of the larvae of the genera Hydraena, Ochthebius and Limnebius may easily cause them to be confounded with silphid larvae... , with a scaphidiid larva, or with some small staphylinid larvae... , and they can only be distinguished from them by anatomical differences, which are so minute, that they are difficult to discover ...”. Later, Lawrence & Newton (1982), arrived at a similar position, as did Hansen (1991b) based on adult characters. Crowson (1955, 1967, 1981) and more recently Beutel (1994) consider Hydraenidae as belonging to the Hydrophiloidea. Beutel, based on head characters from adults and larvae, makes a strong case to support his hypothesis; he refutes some of the evidence presented by other authors: a) the fimbriate galea found in larvae of hydraenids and other staphylinoids is considered non-homologous; b) the anal hooks common to hydraenids and ptiliid (staphylinoid) larvae are also considered non- homologous; c) similarity between hind wings of hydraenids and other staphylinoids is considered a parallel reduction in both groups; d) several synapomorphies of

176 Staphylinoidea (including Hydraenidae) listed by Lawrence & Newton (1982) are also considered either parallelisms or convergencies. To support his point of view, Beutel listed several characters considered to be autapomorphic for Hydrophiloidea (sensu Beutel): a) cephalic egg bursters in larvae; b) aquatic existence; c) the presence of macro- and microplastron in adults; d) a stridulatory file on the basal abdominal pleuron of adult beetles; e) similar egg laying habits, the use of silk to protect the eggs; f) the use of the antennae by adults as a mechanism for gas exchange. From my analysis using preimaginal characters, it is evident that Hydraenidae do not share many characters with Hydrophiloidea, and that Histeridae is a better sister group of the hydrophiloids. There are a number of characters that support this hypothesis: a) Anal hooks are present in hydraenids, but absent in all known hydrophiloid and histerid larvae; b) the complete sclerotization of the terga and sterna of hydraenids is not present in any known hydrophiloid or histerid larvae; c) hydraenid beetles have a free labrum, while hydrophiloids (and also histerids) have it fused to the clypeus; d) hydraenids have annular spiracles, hydrophiloids and histerids have biforous spiracles (except for the 8th pair in metapneustic hydrophiloids, modified in the metapneustic larvae); e) hydraenids have a well developed molar area, and also a prostheca in their mandibles, this molar area (with the exception of Hydrochidae, which have a “pseudomolar area” of unclear function since feeding habits have not been observed) and the prostheca are absent in hydrophiloids and histerids; f) the head is inclined in hydraenids, while hydrophiloids and histerids are prognathous; g) hydraenids seem to be non-predatory, while hydrophiloids and histerids are predatory (Hydrochidae is still unknown); h) the ligula of the hydraenid labium is similar to those of other staphylinoids; i) sclerotization on thoracic segments of hydraenids is more extense (shared with other staphylinoids) than that of hydrophiloids; j) the scape of the antenna is very short in hydraenids (shared with other staphylinoids), while in most

177 hydrophiloids the scape is the longest segment (except for Epimetopidae); k) hydraenids lack a palpifer, and this structure is present in all known hydrophiloids and histerids; 1) the palpifer carries the galea in hydrophiloids (also histerids), while in hydraenids the galea is on the stipes. Reanalyzing the characters mentioned by Beutel as being autapomorphies for Hydrophiloidea (sensu Beutel), several of those could be considered convergences due to an aquatic existence. There are many families of beetles that have become adapted to aquatic environments, and some of them have developed macro- and microplastrons (they are also present in Hemiptera), so this character could well be homoplasious for hydraenids and aquatic hydrophiloids. Sound-producing structures (such as the stridulatory file) are not uncommon among aquatic insects (Aiken 1985), because sound is probably one of the best ways to communicate in a fluid environment. The last two characters listed by Beutel are interesting, and make a strong case for his hypothesis. Adult hydrophiloids and hydraenids have similar respiratory habits, using their antennae to break the water’s surface and provide a point of contact between the atmosphere and the plastron on the ventral side of the body (this in turn connected to the subelytral reservoir). The point that can be argued here is that the structure of the antenna is different in hydraenids and hydrophiloids (Leech & Chandler 1956, Bachmann 1981); the antennalclub in Hydraenidae has five segments beyond the cupule, while in hydrophiloids has only three beyond the cupule, so the similar respiratory habit could be interpreted as a behavioral convergence. The second character is the use of silk to surround the eggs, but there is a significant difference between both hydraenids and hydrophiloids. In the first place hydraenids cover their eggs with only a loose web, while hydrophiloids construct elaborated egg cases; hydraenids lay eggs singly, while hydrophiloids (except for Hydrochidae) lay eggs in groups of two or more.

178 b- Relationships within Hydrophiloidea: There is more than one phylogenetic hypothesis on the relationships among hydrophiloid families. For a more detailed discussion the works by Hansen (1991, 1995) and Beutel (1994) should be consulted. Here I will focus on the effect of immature characters in the phylogeny of Hydrophiloidea. Both the unrooted tree and the rooted trees obtained from the analysis of immatures (Figures 115A, B and 116) show two different clades: Spercheidae + Hydrochidae + Hydrophilidae, and Georissidae + Helophoridae + Epimetopidae. This grouping is influenced by a set of characters related to the development of a spiracular atrium. In order to become metapneustic, hydrophiloid larvae have to undergo a number of modifications. In the first place the thoracic and first seven abdominal pairs of spiracles became non-functional, secondly the spiracles on abdominal segment eight became enlarged and annular (instead of biforous), a requirement to satisfy the demands of gas exchange. In third place, the tenth abdominal segment became extremely reduced, and segments eight and nine were modified to form the spiracular atrium or “pocket,” which can be opened or closed at will by the larva. Also associated with this is the reduction of the urogomphi, which would interfere with the closing of the spiracular atrium. All these characters are shared by Hydrophilidae, Hydrochidae, and Spercheidae, and it would seem unlikely to think that they developed more than once as is suggested by Beutel (Figures 114A, B) and by Hansen (Figure 112B). It is also unlikely, as Hansen suggested, that the spiracular atrium was ancestral to hydrophiloids, and his rejection of the 534-step cladogram seems justified under this light. But if we take a different look at his 534-step tree as an unrooted tree (Figure 113 A) we can see the that the two basic clades obtained with immature characters are

179 represented; the only difference is in the arrangement of the families within each clade. By choosing the 535-step cladogram, Hansen changed radically the relationships among hydrophiloid families, and all the characters associated with the spiracular atrium became homoplasious for Spercheidae + Hydrophilidae on one side, and Hydrochidae on the other (Figure 112B and 113B). When we look at the clade formed by Helophoridae + Georissidae + Epimetopidae, there are several characters that support it. In the first place they are holopneustic (1 + 8); in the second place the structure of the labroclypeus is similar, with a single median projection, large lateral lobes of the epistome that project further than the nasale, and four or five large setae projecting mediad from these lobes. They also share a labium without ligula (lost in Hydrochidae and some Hydrophilidae), they have a very large palpifer and ten well developed abdominal segments.

I have made a case for the grouping of the two basic clades of hydrophiloids, based on the use of preimaginal characters, now I will analyze these characters combined with Hansen’s adult characters. In order to compare different sets of characters (i.e. larval/adult, o r morphological/molecular), there are two different approaches. The first one, also called taxonomic congruence (Kluge 1989), is to use them independently and then obtain a consensus tree from the cladograms obtained with each data set (Mickevich 1978), a three step process. The other way is to combine all the characters in one matrix (Kluge 1989) and analyze them together, this is known as the total evidence approach or character congruence, a two step process. This second approach is the one applied to the combined data for hydrophiloids. The analysis obtained by the total evidence approach produced a single tree (Figure 117A), which retains the two basic clades obtained from the characters of the immature stages, and also the unrooted tree from Hansen’s 534-step cladogram. The

180 difference is that there is some rearrangement within each clade. Helophoridae and Georissidae were sister groups in my analysis, (Figure 115A, B), now Epimetopidae is the sister group of Georissidae (Figure 117A, B). The other clade has a similar change, Hydrochidae and Spercheidae were sister groups in my first analysis, and now Hydrophilidae and Spercheidae are sister groups. What I consider important from this combined evaluation is that the two main clades hold. In this case characters from the preimaginal stages are dictating the topology at the base of the tree. On the other hand the rearrangement of families within each clade is influenced by the adult characters. Combination of data sets commonly result in such answers as this where each data set contributes its own strength and the total solution is novel, not one or the other of the independent solutions (Chippindale & Weins 1994). More than fighting each other, these two sets of characters are complementing each other, and this can be tested by using the incongruence metric (Mickevich & Farris 1981). This test (Appendix F) compares the number of extra steps of the combined matrix (for the shortest tree) with the number of extra steps of each of the individual trees, and is represented by the following equation:

ESc - [ESI + ESa] CS

ESc = extra steps of the combined tree ESI = extra steps of the tree from characters from immature stages ESa = extra steps of the tree from adult characters CS = total steps of the tree from the combined matrices

181 This equation explains what percentage of the length of the tree is due to conflict between data sets. This value would be 0 if no extra steps are introduced by conflict between data sets. In this case incongruence is only 0.034 (3.4 %), an extremely low percentage. This means that the two sets of data contradict each other very little.

Conclusions

The analysis based on characters from the preimaginal stages supports the position of Hydraenidae within the Staphylinoidea, and not as part of Hydrophiloidea as proposed by Crowson (1955, 1967, 1981) and Beutel (1994). It also agrees with other hypotheses (Hansen 1991, 1995) that propose histeroids as the sister group of Hydrophiloidea. From the combined analysis, the most parsimonious tree is the one represented in Figure 117A, and since it is the one supported by a larger amount of information, it is the one accepted here to represent the relationships among the families of Hydrophiloidea. Larval characters appear most informative at the base and adult characters most informative at the apex of the tree. It is also consistent with a unique origin of the spiracular atrium, dividing hydrophiloid beetles into two clades, one including those larvae with an holopneustic respiratory system, and the other with metapneustic larvae.

182 FIGURE 1 Helophorus orientalis; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdom inal segment 9, dorsal view. Scale bars: A = 2 m m ; B and C = 0.2 mm.

183 W m m .. •. •.'■'■ '(iiiWtt'f imu>ww3 POOS

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Figure 1

184 FIGURE 2 Helophorus orientalist third instar larva. (A) Right antenna, dorsal view. (B) Labroclypeus, dorsal view. (C) Labium, dorsal view. (D) Right mandible, dorsal view. (E) Right maxilla, dorsal view. Scale bars: 0.1 mm.

185 J

Figure 2

186 FIGURE 3 Helophorus orientalis; pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. Scale bars: 1 mm.

187 Figure 3

188 FIGURE 4 Epimetopus trogoides; first or second instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B = 0.1 mm.

189 Figure 4

190 FIGURE 5 Epimetopus trogoides; first or second instar larva. (A) Left mandible, dorsal view. (B) Labroclypeus, dorsal view. (C) Left antenna, dorsal view. (D) Right maxilla, dorsal view. (E) Labium, dorsal view. Scale bars: 0.05 m m .

191 Figure 5

192 FIGURE 6 Georissus sp.; second or third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 9 and 10, dorsal view. Scale bars: A = 1 mm; B and C = 0.1 mm.

193 ffff'v* r i "|*! i i- \ ~ -

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Figure 6

194 FIGURE 7 Georissus sp.; second or third instar larva. (A) Labroclypeus, dorsal view. (B) Right antenna, dorsal view. (C) Labium, dorsal view. (D) Right maxilla, dorsal view. (E) Right mandible, dorsal view. Scale bars: 0.05 mm.

195 B

Figure 7

196 FIGURE 8 Georissus sp.; second or third instar larva. (A) Left prothoracic leg, antero­ lateral view. (B) Detail of abdominal sclerites. Scale bars: 0.05 mm.

197 Figure 8

198 FIGURE 9 Hydrochus rufipes; first instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Labroclypeus, dorsal view. (D) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 0.25 mm; B and D = 0.1 mm; C = 0.05 mm.

199 Figure 9 FIGURE 10 Hydrochus rufipes; first instar larva, egg case (H. Squamifer). (A) Left antenna, dorsal view. (B) Left maxilla, dorsal view. (C) Egg case. (D) Labium, dorsal view. (E) Right mandible, dorsal view. Scale bars: A, B, and E = 0.05 mm; C = 0.5 mm; D = 0.025 mm. C after Richmond (1920).

201 Figure 10

202 FIGURE 11 Spercheus emarginatus; third instar larva and egg case. (A) Habitus. (B) Head capsule, dorsal view. (C) Egg case, dorsal view. (D) Egg case, ventral view. Scale bars: A = 1 mm; B = 0.5 mm; C and D = 2 mm.

203 Figure 11

204 FIGURE 12 Spercheus emarginatus; third instar larva. (A) Left antenna, dorsal view. (B) Right mandible, ventral view. (C) Left mandible, dorsal view. (D) Labium, dorsal view. Scale bars: 0.2 mm.

205 Figure 12

206 FIGURE 13 Spercheus emarginatus; third instar larva. (A) Labroclypeus, dorsal view. (B) Abdominal segments 8 and 9, dorsal view. (C) Right maxilla, dorsal view. Scale bars: 0.2 mm.

207 Figure 13

208 FIGURE 14 Sperchopsis tessellata; third instar larva. (A) Habitus. (B) Head capsule,

dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B = 0.5 mm; C = 0.2 mm. A after Spangler (1961).

209 B

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210 FIGURE 15 Sperchopsis tessellata; third instar larva. (A) Right mandible, dorsal view. (B) Labroclypeus, dorsal view. (C) Right antenna, dorsal view. (D) Right maxilla, dorsal view. (E) Labium, dorsal view. Scale bars: 0.2 mm.

211 Figure 15 FIGURE 16 Sperchopsis tessellata; pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. Scale bars: 2 mm. All after Spangler (1961).

213 Figure 16

214 FIGURE 17

Ametor scabrosus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 m m ; B = 0.5 mm; C = 0.2 mm.

215 Figure 17

216 FIGURE 18 Ametor scabrosus; third instar larva. (A) Labroclypeus, dorsal view. (B) Right mandible, dorsal view. (C) Right antenna, dorsal view. (D) Left maxilla, dorsal view. (E) Labium, dorsal view. Scale bars: A, C-E= 0.1 mm; B = 0.2 mm.

217 4 /T-V'yV'

Figure 18 FIGURE 19 Ametor scabrosus; pupa. (A) )Ventral view. (B) Dorsal view. Scale bar: 2 mm. Both after Spangler (1962.

219 vw/ \ \ U * M

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/

Figure 19

220 FIGURE 20 Anticura flinti', third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdom inal segments 8 and 9, dorsal view. Scale bar: A = 2 m m . All after Spangler (1979).

221

FIGURE 21 Anticura flinti; third instar larva. (A) Labroclypeus, dorsal view. (B) Left maxilla, dorsal view. (C) Right antenna, dorsal view. (D) Right mandible, dorsal view. (E) Labium, dorsal view. All after Spangler (1979).

223 Figure 21 FIGURE 22 Anticura flinti; pupa. (A) Ventral view. (B) Dorsal view. Scale bar: 2 mm. Both after Spangler (1979).

225 n z

ni

Figure 22

2 2 6 FIGURE 23 Berosus pugnax; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 7 and 8, dorsal view. Scale bars: A = 2 mm; B and C = 0.5 mm. All after Archangelsky (1994b).

227 w&titMj'ii il'J l tm * * :

Figure 23

228 FIGURE 24 Berosus pugnax; third instar larva. (A) Labroclypeus, dorsal view. (B) Left antenna, dorsal view. (C) Labium, dorsal view. (D) Right maxilla, dorsal view. (E) Left mandible, dorsal view. (F) Right mandible, dorsal view. Scale bars: A, B, D-F = 0.2 mm; C = 0.1 mm. All after Archangelsky (1994b).

229 k /

Figure 24

230 FIGURE 25 Berosus spp..; egg cases and pupa. (A) Egg case of B. pugnax. (B) Egg case of B. corrini. (C) Egg case of B. hoplites. (D) Pupa of B. pugnax, ventral view. (E) Pupa of B. pugnax, dorsal view. Scale bars: 2 mm. All after Archangelsky (1994b).

231 B '■I

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9

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Figure 25 FIGURE 26 Berosus spp.; pupae. (A) Pupa of B. corrini, ventral view. (B) Pupa of B. corrini., ventral view. (C) Pupa of B. hoplites, ventral view. (D) Pupa of B. hoplites, dorsal view. Scale bars: 2 mm. All after Archangelsky (1994b).

233 Figure 26 FIGURE 27 Derallus angustus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Distribution of right stemmata. (D) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and D = 0.1 mm. All after Archangelsky & Durand (1992b).

235 Figure 27

236 FIGURE 28 Derallus angustus; third instar larva. (A) First abdominal segment, dorsal view. (B) Right antenna, dorsal view. (C) Labroclypeus, dorsal view. (D) Right maxilla, dorsal view. (E) Right mandible, dorsal view. (F) Labium, dorsal view. Scale bars: 0.1 mm. All after Archangelsky & Durand (1992b).

237 Figure 28

238 FIGURE 29 Derallus angustus; pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. Scale bars: 1 mm. All after Archangelsky & Durand (1992b).

239 ~~ < / ✓ *

Figure 29

240 FIGURE 30 Chaetarthria sp ; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 0.5 mm; B and C = 0.1 mm.

241 Figure 30

242 FIGURE 31 Chaetarthria sp.; third instar larva. (A) Left antenna, dorsal view. (B) Labroclypeus, dorsal view. (C) Labium, dorsal view. (D) Right maxilla, dorsal view. (E) Left mandible, dorsal view. Scale bars: A and C = 0.025 mm; B, D and E = 0.05 mm.

243 Figure 31 FIGURE 32

Guyanobius adocetus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Head capsule, ventral view. Scale bars: A = 1 mm; B and C = 0.5 mm. All after Spangler (1986).

245 B

£

Figure 32

246 FIGURE 33 Guyanobius adocetus; third instar larva. (A) Left antenna, dorsal view. (B) Labroclypeus, dorsal view. (C) Right mandible, dorsal view. (D) Labium, dorsal view. (E) Right maxilla, dorsal view. All after Spangler (1986).

247 Figure 33

248 FIGURE 34 Paracymus subcupreus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and C = 0.2 mm.

249 Figure 34

250 FIGURE 35 Paracymus subcupreus; third instar larva. (A) Labroclypeus, dorsal view. (B) Left antenna, dorsal view. (C) Right mandible, dorsal view. (D) Labium, dorsal view. (E) Left maxilla, dorsal view. Scale bars: A, B, D and E = 0,05 mm; C = 0.1 mm.

251 Figure 35 FIGURE 36 Paracymus subcupreus; pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. Scale bars: 1 nun.

253 Figure 36

254 FIGURE 37 Crenitis sp; third instar larva. (A) Habitus. (B) Head capsule, dorsal view.

(C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and C = 0.2 mm.

255 Figure 37 FIGURE 38 Crenitis sp; third instar larva. (A) Right antenna, dorsal view. (B)

Labroclypeus, dorsal view. (C) Right mandible, dorsal view. (D) Right maxilla, dorsal view. (E) Labium, dorsal view. Scale bars: 0.1 mm.

257 >

Figure 38

258 FIGURE 39 Crenitis punctatostriata; pupa. (A) Ventral view. (B) Dorsal view. (C) Distribution of styli on pronotum and head, dorsal view. (D) Styli. Scale bar: 1 mm. All after Matthey (1977).

259 -A.

Figure 39

260 FIGURE 40

Anacaena infuscata; third and first instar larvae. (A) Habitus, third instar larva. (B) Right mandible, dorsal view. (C) Right antenna, dorsal view. Scale bar: 1 mm. All after Richmond (1920).

261 Figure 40

262 FIGURE 41 Anacaena infuscata; first instar larva and egg case. (A) Labroclypeus, dorsal view. (B) Egg case. (C) Labium, dorsal view. (D) Right maxilla, dorsal view. All after Richmond (1920).

263 \

Figure 41

264 FIGURE 42

Notionotus liparus; first instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Labroclypeus, dorsal view. (D) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 0.2 mm; B = 0.1 mm; C and D = 0.05 mm.

265 Figure 42

266 FIGURE 43 Notionotus liparus; first instar larva. (A) Left mandible, dorsal view. (B) Left antenna, dorsal view. (C) Right mandible, dorsal view. (D) Left maxilla, dorsal view. (E) Labium, dorsal view. Scale bars: 0.05 mm.

267 £

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Figure 43

2 6 8 FIGURE 44 Laccobius minutoides; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and C = 0.2 mm.

269 m m m

Figure 44 FIGURE 45 Laccobius minutoides', third instar larva. (A) Labroclypeus, dorsal view. (B) Right mandible, dorsal view. (C) Right maxilla, dorsal view. (D) Left antenna, dorsal view. (E) Left mandible, dorsal view. Scale bars: 0.1 mm.

271 Figure 45

111 FIGURE 46

Laccobius minutoides; third instar larva, pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. (D) Larva, labium. Scale bars: A-C = 1 mm; D = 0.025 mm.

273 S v3-/— H ?/ / j

Figure 46

274 FIGURE 47

Oocyclus sp; first instar larva. (A) Habitus. (B) Head capsule, dorsal view.

(C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 0.5mm; B = 0.2 mm; C = 0.1 mm.

275 Figure 47

276 FIGURE 48 Oocyclus sp; first instar larva. (A) Right maxilla, dorsal view. (B) Labium, dorsal view. (C) Left mandible, dorsal view. (D) Right mandible, dorsal view. Scale bars: 0.05 mm.

2 77 Figure 48

278 FIGURE 49 Oocyclus sp; first instar larva and egg case. (A) Labroclypeus, dorsal view. (B) Right antenna, dorsal view. (C) Egg case. Scale bars: A and B = 0.05 m m ; C = 1 mm.

279 Figure 49

280 FIGURE 50

Helochares maculicollis; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B = 0.5 mm; C = 0.2 mm.

2 8 1 MBS

Figure 50 FIGURE 51 Helochares maculicollis; third instar larva. (A) Labroclypeus, dorsal view. (B) Left mandible, dorsal view. (C) Right mandible, dorsal view. (D) Right antenna, dorsal view. (E) Left maxilla, dorsal view. Scale bars: A-C and E = 0.2 mm; D = 0.1 mm.

283 Figure 51

284 FIGURE 52 Helochares maculicollis; third instar larva, pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Distribution of styli on pronotum, dorsal view. (D) Larva, labium, dorsal view. (E) Egg case, ventral view. Scale bars: A, B = 2 mm; D = 0.1 mm; E = 1 mm.

285 Figure 52

286 FIGURE 53 Helobata larvalis (= H. striata ); first instar larva and egg case. (A) Habitus. (B) Head capsule, dorsal view. (C) Egg case, dorsal view. (D) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 0.5 mm; C = 1 mm. All after Spangler (1972).

287

FIGURE 54 Helobata larvalis (= H. striata ); first instar larva. (A) Labroclypeus, dorsal view. (B) Left maxilla, dorsal view. (C) Labium, dorsal view. (D) Left antenna, dorsal view. (E) Left mandible, dorsal view. All after Spangler ( 1972).

289 Figure 54

290 FIGURE 55 Enochrus ochraceus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B and C = 0.2 mm.

291 Figure 55

292 FIGURE 56

Enochrus ochraceus; third instar larva. (A) Labroclypeus, dorsal view. (B) Right maxilla, dorsal view. (C) Right mandible, dorsal view. (D) Left antenna, dorsal view. (E) Left mandible, dorsal view. Scale bars: 0.1 mm.

293 Figure 56 FIGURE 57

Enochrus ochraceus; third instar larva, pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Larva, labium, dorsal view. (D) Egg case. Scale bars: A and B = 1 mm; C = 0.1 mm; D = 2 mm.

295 I \ ' \ \ ' Figure 57 N

296 FIGURE 58

Helocombus bifidus; first instar larva. (A) Habitus. (B) Labium, dorsal view. (C) Head capsule, dorsal view. (D) Labroclypeus, dorsal view. Scale bar: 1 mm. All after Perkins & Spangler (1981).

297 Figure 58

298 FIGURE 59 Cymbiodyta vindicata; third and second instar larvae. (A) Habitus, third instar. (B) Head capsule, dorsal view, second instar. (C) Labroclypeus, dorsal view, second instar (D) Abdominal segments 8 and 9, dorsal view, second instar. Scale bars: A = 2 mm; B and D = 0.2 mm, C = 0.1 mm.

299 B

: o

i

Figure 59

300 FIGURE 60 Cymbiodyta vindicata; second instar. (A) Right maxilla, dorsal view. (B) Right antenna, dorsal view. (C) Labium, dorsal view. (D) Left mandible, dorsal view. (E) Right mandible, dorsal view. Scale bars: 0.1 mm.

301 Figure 60 FIGURE 61 Chasmogenus nitescens; third instar larva. (A) Habitus. (B) Mandibles and labroclypeus, dorsal view. (C) Left maxilla, dorsal view (D) Labium, dorsal view. Scale bars: A = 1 mm; B-D = 0.1 mm. All after Anderson (1976).

303 B

D

Figure 61

304 FIGURE 62

Chasmogenus nitescens; pupa and egg case. (A) Pupa, ventral view. (B) Pupa, lateral view. (C) Egg case. Scale bars: 1 mm. All after Anderson (1976).

305 Figure 62

306 FIGURE 63

Hydrobius melaenus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A =

2 mm; B and C = 0.5 mm.

307 Figure 63

308 FIGURE 64 Hydrobius melaenus; third instar larva. (A) Labroclypeus,dorsal view. (B) Left antenna, dorsal view. (C) Right mandible, dorsal view. (D) Right maxilla, dorsal view. (E) Detail of pubescence and asperities of abdominal segment 8. Scale bars: 0.2 mm.

309 Figure 64

310 FIGURE 65 Hydrobius melaenus; third instar larva, pupa, and egg case. (A) Larva, labium, dorsal view. (B) Egg case. (C) Pupa, ventral view. (D) Pupa, dorsal view. Scale bars: A = 0.2 mm; B-D = 2 mm.

311 Figure 65

312 FIGURE 66 Hydramara argentine, third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bar: 5 mm. All after Spangler (1979).

313 VI

Figure 66

314 FIGURE 67

Hydramara argentina; third instar larva. (A) Labroclypeus, dorsal view. (B) Right antenna, dorsal view. (C) Right mandible, dorsal view. (D) Left maxilla, dorsal view. (E) Labium, dorsal view. All after Spangler (1979).

315 Figure 67 FIGURE 68 Tropisternus spp; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdom inal segments 8 and 9, dorsal view. Scale bars: A = 3 m m ; B = 1 mm; C = 0.5 mm.

317 Figure 68

318 FIGURE 69

Tropisternus .; sp third instar larva. (A) Labroclypeus, dorsal view. (B) Right maxilla, dorsal view. (C) Left mandible, dorsal view. (D) Right mandible, dorsal view. (E) Left antenna, dorsal view. (F) Labium, dorsal view. Scale bars: 0.5 mm.

319 A • • V ’J

li

7

n

x"A v "

A 4 iV\*A JL*\ * l W A AA A<<*A

A * a «

- * { * V A « . A a . »,■» A A /j^W *

Figure 69

320 FIGURE 70 Tropisternus spr, third instar larva, pupa, and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. Scale bars: 2 mm. A and B after Fortich (1980) (T. setiger).

321 Figure 70

322 FIGURE 71 Hydrobiomorpha casta; third instar larva. (A) Habitus. (B) Left mandible, dorsal view. (C) Labium, dorsal view. Scale bars: A = 5 mm; B and C = 0.5 mm. All after Spangler (1973).

323 Figure 71 FIGURE 72 Hydrobiomorpha casta; third instar larva. (A) Abdominal segments 8 and 9, dorsal view. (B) Left maxilla, dorsal view. (C) Right antenna, dorsal view. Scale bars: 0.5 mm. All after Spangler (1973).

325 c

Figure 72

326 FIGURE 73 Hydrochara caraboides and H. soror; third instar larvae. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B = 1 mm; C = 0.5 mm. B after Matta, 1982 (H. soror).

327 Figure 73 FIGURE 74 Hydrochara caraboides; third instar larva. (A) Labroclypeus, dorsal view. (B) Left mandible, dorsal view. (C) Right maxilla, dorsal view. (D) Left antenna, dorsal view. (E) Right mandible, dorsal view. Scale bars: 0.5 mm.

329 E

Figure 74

330 FIGURE 75 Hydrochara caraboides; third instar larva. (A) Labium, dorsal view. (B) Egg case. Scale bars: A = 0.5 mm; B = 5 mm. B after Richmond (1920).

331 .• *. v ^ ^/.:.;: v.::V.V tnk * * \ *A*jk* U* A **AV* — 4 *.* A 4 4. i

Figure 75

332 FIGURE 76

Dibolocelus ovatus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Detail of cuticular asperities. (D) Abdom inal segm ents 8 and 9, dorsal view. Scale bars: A = 10 mm; B = 2 mm; C = 0.5 mm. A-C after Archangelsky & Durand (1992a).

333 Figure 76

334 FIGURE 77 Dibolocelus ovatus; third instar larva. (A) Labroclypeus, dorsal view. (B)

Left mandible, dorsal view. (C) Right mandible, dorsal view. (D) Left maxilla, dorsal view. (E) Labium, dorsal view. (F) Left antenna, dorsal view. Scale bars: 1 mm. All after Archangelsky & Durand (1992a).

335 oo

'■M ■>C

Figure 77

336 FIGURE 78 Dibolocelus ovatus; pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case, lateral view. (D) Egg case, anterior view. Scale bars: 10 mm. All after Archangelsky & Durand (1992a).

337 Figure 78

338 FIGURE 79

Hydrophilus triangularis; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 10 mm; B = 2.5 mm; C = 1 mm.

339 Ia-^I faAirtj&M&ia 0 ^ o

Hfe-,'. .*'» •'.•.***, ,4^! ; i :. *. *. ■ ] 7. • * /.

:\c ;; ’.y.vV.::

* * ,* _■ •*• •_. t'TtM'.'fys.j £/■*■!• V*7.*vii5 c

Figure 79

340 FIGURE 80 Hydrophilus triangularis; third instar larva. (A) Labroclypeus, dorsal view. (B) Left antenna, dorsal view. (C) Right mandible, dorsal view. (D) Left maxilla, dorsal view. (E) Left mandible, dorsal view. Scale bars: 1 mm.

341 Figure 80

342 FIGURE 81 Hydrophilus triangularis; third instar larva, pupa and egg case. (A) Pupa, ventral view. (B) Larva, labium, dorsal view. (C) Egg case, lateral view. (D) Pupa, dorsal view. Scale bars: A, C and D = 10 mm; B = 1 mm. A after Wilson (1923a).

343 Figure 81

344 FIGURE 82 Cylorygmus lineatopunctatus', third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Labroclypeus, dorsal view. (D) Abdominal segments 8 and 9, dorsal view. Scale bar: 1 mm. All after Spangler (1979).

345 Figure 82

346 FIGURE 83

Cylorygmus lineatopunctatus; third instar larva. (A) Left maxilla, dorsal view. (B) Right mandible, dorsal view. (C) Right antenna, dorsal view. (D) Detail of lateral and spiracular tubercles. (E) Labium, dorsal view. All after Spangler (1979).

347 Iy

D

Figure 83

348 FIGURE 84 Cylorygmus lineatopunctatus; pupa. (A) Ventral view. (B) Dorsal view. Both after Spangler (1979).

349 Figure 84

350 FIGURE 85 Phaenonotum exstriatum; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and C = 0.2 mm. All after Archangelsky & Durand (1992c).

351 ft j1.'f:'' '7''! T?

tViiililyi

Figure 85 FIGURE 86

Phaenonotum exstriatum; third instar larva. (A) Labroclypeus, dorsal view. (B) Right mandible, dorsal view. (C) Right antenna, dorsal view. (D) Right maxilla, dorsal view. (E) Labium, dorsal view. Scale bars: A = 0.05 mm; D-E = 0.1 mm. B after Archangelsky & Durand (1992c).

353 Figure 86

354 FIGURE 87 Phaenonotum exstriatum; pupa and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. Scale bars: 1 mm. All after Archangelsky & Durand (1992c).

355 . * •« j — v j . : . .

Figure 87

356 FIGURE 88 Dactylosternum cacti; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B = 0.5 mm; C = 0.4 mm. All after Archangelsky (1994a).

357 *. *. •'V*ti&At-»i&k&tt*m#ii\

£yfW W Ol, i CUwV&fojjJgfa :'. v: *. V.

W S m z M

>*■;'.• .*.•••. •• •' : ‘;,>isAf.v«‘?y<"; ■,..J.«4A»»t»«, V V .jO r.i.V TO ^J/.V ’’•: • . -• .• m ./Aw-J t. »v

• • .• :• ^«v»<»«.>>ikw4''aw '.''

rrr",\tj&AvmWW.

Figure 88

358 FIGURE 89

Dactylosternum cacti', third instar larva. (A) Right maxilla, dorsal view. (B) Labroclypeus, dorsal view. (C) Left antenna, dorsal view. (D) Hypopharyngeal lobe, dorsal view. (E) Labium, dorsal view. Scale bars: A-C = 0.2 mm; D and E = 0.1 mm. All after Archangelsky (1994a).

359 Figure 89

360 FIGURE 90 Dactylosternum cacti; third instar larva, pupa, and egg case. (A) Larva, left mandible, dorsal view. (B) Larva, right mandible, dorsal view. (C) Egg case. (D) Pupa, ventral view. (E) Pupa, dorsal view. Scale bars: A and B = 0.2 mm; C-E = 2 mm. All after Archangelsky (1994a).

361 362 FIGURE 91 Dactylosternum sp; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 m m ; B = 0.5 mm; C = 0.25 mm.

363 Figure 91 FIGURE 92 Dactylosternum sp; third instar larva. (A) Labroclypeus, dorsal view. (B) Right mandible, dorsal view. (C) Left antenna, dorsal view. (D) Right maxilla, dorsal view. (E) Left mandible, dorsal view. Scale bars: 0.1 mm.

365 Figure 92 FIGURE 93

Dactylosternum sp.; third instar larva, egg case. (A) Larva, labium and hypopharyngeal lobe, dorsal view. (B) Egg case. Scale bars: A = 0.1 mm; B = 1 mm.

367 7 V p & W : . ';*.V:• .V .:.;■ •: > -.V

;k?-V/."’ v. 1 v V -1-.:-” ; .. I •-’:, *: j

Figure 93

368 FIGURE 94 Cercyon praetextatus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B = 0.2 mm; C = 0.5 mm.

369 Figure 94

370 FIGURE 95 Cercyon praetextatus; third instar larva. (A) Labroclypeus, dorsal view. (B) Right mandible, dorsal view. (C) Left antenna, dorsal view. (D) Left mandible, dorsal view. (E) Labium, ventral view. (F) Left maxilla, dorsal view. Scale bars: A, B, D, and F = 0.1 mm; C and E = 0.05 mm.

371 r" A V'"V

Figure 95

372 FIGURE 96 Cercyon praetextatus; third instar larva, pupa, and egg case. (A) Pupa, ventral view. (B) Larva, prothoracic leg. (C) Pupa, dorsal view. (D) Egg case. Scale bars: 1 mm.

373 Figure 96 FIGURE 97 Pelosoma sp; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and C = 0.2 mm.

375 Figure 97 FIGURE 98 Pelosoma sp; third instar larva. (A) Labroclypeus, dorsal view. (B) Left maxilla, dorsal view. (C) Right mandible, dorsal view. (D) Left antenna, dorsal view. (E) Left mandible, dorsal view. Scale bars: A = 0.1 mm; B-E = 0.05 mm.

377 Figure 98

378 FIGURE 99 Pelosoma sp; third instar larva, pupa, and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. (D) Labium and hypopharyngeal lobe, ventral view. Scale bars: A and B = 1 mm; C = 2 mm; D = 0.05 mm.

379 Figure 99 FIGURE 100 Cryptopleurum minutum; third instar larva. (A) Habitus. (B) Head

capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and C = 0.2 mm.

381 o o

■■'■■■■■• ■':J i ■■(■■.?.

i.\ i.!; !.y\ y'.v.

Figure 100

382 FIGURE 101 Cryptopleurumminutum ; third instar larva. (A) Left antenna, dorsal view. (B) Labroclypeus, dorsal view. (C) Right mandible, dorsal view. (D)

Left maxilla, dorsal view. (E) Left mandible, dorsal view. Scale bars: 0.05 m m .

383 Figure 101

384 FIGURE 102 Cryptopleurum mitt u turn; third instar larva, pupa, and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Egg case. (D) Labium and hypopharyngeal lobe, ventral view. Scale bars: A-C = 1 mm; D = 0.025 mm.

385 Figure 102

386 FIGURE 103 Pemelus costatus; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Abdominal segments 8 and 9, dorsal view. Scale bars: A =1 mm; B = 0.2 mm; C = 0.25 mm.

387 I

Figure 103

388 FIGURE 104 Pemelus costatus; third instar larva. (A) Labroclypeus, dorsal view. (B) Left mandible, dorsal view. (C) Left antenna, dorsal view. (D) Right maxilla, dorsal view. (E) Right mandible, dorsal view. Scale bars: A, C, and D = 0.05 mm; B and E = 0.1 mm.

389 Figure 104

390 FIGURE 105 Pemelus costatus', third instar larva, pupa, and egg case. (A) Pupa, ventral view. (B) Pupa, dorsal view. (C) Labium and hypopharyngeal lobe, ventral view. (D) Egg case. Scale bars: A, B, and D = 1 mm; C = 0.05 mm.

391 Figure 105

392 FIGURE 106

Megasternum obscurum; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Labroclypeus, dorsal view. (D) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 1 mm; B and D = 0.2 mm; C = 0.05 mm. All after Quennedey (1965).

393 Figure 106 FIGURE 107

Megasternum obscurum; third instar larva. (A) Labium and hyp°pharyngeal lobe, ventral view. (B) Left maxilla, ventral view. (C) Right antenna, dorsal view. (D) Left mandible, dorsal view. (E) Right mandible, dorsal view. Scale bars: A-C = 0.05 mm; D and E = 0.1 mm. All after Quennedey (1965).

395 Figure 107

396 FIGURE 108 Sphaeridium scarabaeoides; third instar larva. (A) Habitus. (B) Head capsule, dorsal view. (C) Detail of asperities on projections of abdominal segment 8. (D) Abdominal segments 8 and 9, dorsal view. Scale bars: A = 2 mm; B and D = 0.5 mm.

397 -s/; ; \ v: -yj

S i .* V*•'

T'

Figure 108

398 FIGURE 109 Sphaeridium scarabaeoides; third instar larva. (A) Labium, dorsal view. (B)

Labium and hypopharyngeal lobe, ventral view. (C) Right prothoracic leg. Scale bar: 0.1 mm. B after Quennedey (1965).

399 Figure 109

400 FIGURE 110 Sphaeridium scarabaeoides; third instar larva. (A) Labroclypeus, dorsal view. (B) Right maxilla, dorsal view. (C) Right antenna. (D) Right mandible, dorsal view. (E) Left mandible, dorsal view. Scale bars: 0.1 mm.

401 A

■ p ,

Figure 110

402 FIGURE 111 Sphaeridium scarabaeoides; pupa. (A) Ventral view. (B) Dorsal view. Scale bar: 2 mm.

403 Figure 111

404 FIGURE 112 Cladograms obtained by Hansen (1991). (A) 534-step cladograms, obtained for 33 taxa and 176 characters (Cl = 0.34), only the hydrophiloid families are represented. (B) 535- step cladogram, obtained for 33 taxa and 176 characters (Cl = ?).

405 A Spercheidae Hydrochidae

Helophoridae

Epimetopidae

Georissidae

Hydrophilidae

B Helophoridae Epimetopidae

Georissidae

Hydrochidae

Spercheidae

Hydrophilidae

Figure 112

406 FIGURE 113 Representation of Hansen’s cladograms as unrooted trees. (A) 534-step cladogram. (B) 535-step cladogram.

407 A

Spercheidae Hydrochidae Epimetopidae

Hydrophilidae Helophoridae Georissidae

B

Spercheidae Helophoridae Hydrochidae

Hydrophilidae Epimetopidae Georissidae

Figure 113

408 FIGURE 114 Cladogram obtained by Beutel (1994). (A) Cladogram including Hydraenidae, obtained for 11 taxa and 39 characters (number of steps and Cl are not provided by the author). (B) Same cladogram represented as an unrooted tree.

409 A Hydraenidae

Spercheidae

Hydrochidae

Helophoridae

Epimetopidae

Georissidae

Hydrophilidae B

Hydraenidae Helophoridae Epimetopidae

Spercheidae Hydrochidae Hydrophilidae Georissidae

Figure 114

410 FIGURE 115 Equally parsimonious cladograms obtained with characters from immature stages. Both cladograms obtained for 11 taxa and 44 characters (Cl = 0.68, excluding uninformative characters, RI = 0.737).

411 Nicrophorus Ochthebius Histeridae Helophoridae Georissidae Epimetopidae

Hydrochidae Spercheidae Sperchopsini

Hydrophilina Megasternini

Nicrophorus Ochthebius Histeridae Helophoridae Georissidae Epimetopidae

Hydrochidae Spercheidae Megasternini

Hydrophilina Sperchopsini FIGURE 116 Representation of cladograms obtained with characters from immature stages as unrooted trees.

413 Spercheidae Hydrophilidae Helophoridae

Hydrochidae Epimetopidae Georissidae

Figure 116

414 FIGURE 117 Cladogram obtained by combining characters from adult and preimaginal stages. (A) 236-step cladogram, obtained for 9 taxa and 132 characters (Cl = 0.61, excluding uninformative characters, RI = 0.48). (B) Same represented as an unrooted tree (Hydraenidae has been excluded).

415 A Hydraenidae

Helophoridae Epimetopidae Georissidae Hydrochidae

Spercheidae

Hydrophilidae

B

Hydrophilidae Helophoridae Epimetopidae

Spercheidae Hydrochidae Georissidae

Figure 117

416 APPENDIX A

Characters from egg cases:

1- Eggs laid singly (0); eggs laid in groups of two or more (1).

2- Eggs uncovered (0); eggs covered by a loose webb (1); eggs enclosed inside a two layered egg case (2). Non-additive.

3- Egg case laid on the substrate (0); egg case carried by the female (1).

4- Parental care absent (0); parental care present (1).

General characters of the larvae:

3- Number of larval instars 3 (0); number of larval instars 2(1).

6- Larvae terrestrial (0); larvae aquatic or semiaquatic (1).

7- Larvae holopneustic (0); larvae metapneustic (1).

8- Thoracic and abdominal spiracles 1-7 annular (0); thoracic and abdominal spiracles 1-7 biforous (1).

9- Spiracles on segment eight annular, similar to those on other segments (0); spiracles biforous (1); spiracles annular enlarged (2). Non-additive

10- Spiracular atrium absent (0); spiracular atrium present (1).

11- Larvae non-predatory (0); larvae predatory (1).

Characters from the larval headcapsule:

12- Labrum free (0); Iabrum fused to clypeus (1).

13- Labroclypeus (or labrum) symmetrical (0); labroclypeus asymmetrical (1).

14-Lateral lobes ofepistome absent (0); lateral lobes ofepistome much larger than nasale, with 4 or 5 large setae or projections pointing mediad (1); lateral lobes ofepistome smaller, without large setae or projections (2). Non-additive.

15- Antennal and mandibular foramens separated by a sclerotized bridge (0); antennal and mandibular foramens separated by a membrane (1).

16- Cervical sclerites absent (0); cervical sclerites present (1).

417 17- Number of stemmata 0 (0); 1 (1); 5 (2); 6 (3). Non-additive.

18- Gular sutures separate (0); gular sutures fused (1); gular sutures absent (2).

19- Coronal sulcus long (0); coronal sulcus short (1); coronal sulcus absent (2).

20- Head inclined (0); head prognathous (1).

Characters from the larval mouthparts:

21- Antennae with 1 sensory appendage (0); antenna with two sensory appendages (1).

22- Mandibles symmetrical (0); mandibles asymmetrical (1).

23- Mandibles with prostheca (0); mandibles without prostheca (1).

24- Mandibles with penicillus (0); mandibles without penicillus (1).

25- Mandibles without rctinacular tuft (0); mandibles with retinacular tuft (1).

26- Molar area present (0); molar area absent (1).

27- Cardo undivided (0); cardo divided (1); cardo absent (2). Non-additive.

28- Palpifcr absent (0); palpifcr present, as long or longer than stipes (1); palpifer present, shorter than stipes (2). Non-additive.

29- Lacinia well developed (0); lacinia absent (1).

30- Galea on stipes (0); galea on palpifer (1).

31- submentum free (0); submentum attached to the headcapsule (1).

32- Labium with sclerotized mentum (0); labium with mentum unsclerotized (1).

33- Ligula short, lobed and membranous (0); ligula sclerotized (1); ligula absent (2). Non­ additive.

Characters from the thorax and abdomen:

34- Abdominal segment 10 well developed, visible (0); abdominal segment 10 reduced or absent ( 1).

35- Abdominal segment 10 without subterminal claws (0); abdominal segment 10 with terminal claws (1 ).

36- Urogomphy large, 2- or 3-segmented (0); urogomphy small, 1-segmented (1).

37- Abdominal stemites complete (0); abdominal stemites reduced or absent (1).

38- Abdominal tergites complete (0); abdominal tergites reduced or absent (1).

418 39- Abdominal segment 9 normal (0); abdominal segment nine reduced (1).

Characters from the pupae:

40- Cephalic styli 2 or less (0); cephalic styli 3 or more (1).

41- W ith styli on clypeus and labrum (0); without styli on clypeus and labrum (1).

42- Styli on wingpads absent (0); styli on wingpads present (1).

43- Pupae with both styli and setae (0); pupae only with styli (1); pupae only with setae (2). Non­ additive.

44- Discal styli (pronotum) present (0); discal styli absent(l).

419 APPENDIX B

Data matrix used for the analysis with larval characters:

TAXA CHARACTERS

1 1 1 1 1 1 1 1 1 1 2 2222222223 333333333 4 4 4 4 4 1234567890 1234567890 1234567890 123456789 01234

Nicrophorus 10-1000000 0000001200 0011010010 0 0 0 0 0 0 1 1 0 1 1 0 1 1 Ochthebius 0100010000 0000002000 0001000010 000010010 01000 Histeridae 00-0100110 111010a201 1010012201 112000100 1 0 1 2 1 Helophoridae 1200010110 1101003121 1010111101 1 0 2 0 0 0 1 0 0 0 1 0 1 0 Epimetopidae 1210010110 1101003121 0011111101 1 0 2 0 0 1 1 0 0 ????? Georissidae ????010110 1101003111 1010111101 102001100 ????? Hydrochidae 0 2 0 0 0 1 1 1 2 1 7102003021 0011001211 102101101 ????? Spercheidae 1210011121 1102002021 0011010211 0 0 1 1 0 1 1 0 1 ????? Sperchopsini 1200011121 1112013111 0011011201 1 0 1 1 0 1 1 0 1 0 1 0 1 0 Hydrophilina 1 2 0 0 0 1 1 1 2 1 lla2013111 0111011201 1 0 1 1 0 1 1 0 1 0 1 0 1 0 Megasternini 12000bll21 1112013121 0111011201 101101101 0 1 0 1 0

Definitions

- = character does not apply to that taxon a = multistate character for that taxon (0/1), 0 is supposed to be ancestral and 1 derived, b = multistate character for that taxon (1/0), 1 is supposed to be ancestral and 0 derived. 7 = data not available for that taxon.

420 APPENDIX C

Characters of adults (both sexes), from Hansen (1991):

1- Labrum widest at base, not narrowed posteriorly (0); widest anterior to base, narrowed posteriorly (1).

2- Lateral margins of labrum without or with only sparse setae (0); with dense setae (1).

3- Anterior margin of labrum at most with sparse setae (0); with a fringe of dense setae (1).

4- Labrum not retracted under clypeus (0); to a great extent retracted under clypeus, entirely (or almost) concealed by clypeus (1).

3- Lateral margins of labrum without spines or spinelike setae (but often with fine hairlike setae) (0); with a series of stout spines or spinelike setae (rather than fine hairlike setae) (1).

6- Lateral margins of clypeus not excised anterior to eyes (0); abruptly excised anterior to eyes ( 1).

7- Anterior margin of clypeus truncate or slightly convex (0); anterior margin concave, the anterior comers distinctly protruding (1).

8- Clypeus demarcated from frons by a transverse groove (0); at most demarcated by a fine transverse suture (1).

9- Eyes demarcated from temporae by a ridge (0); not demarcated by a ridge.

10- Head abruptly narrowed immediately behind eyes (0); not abruptly narrowed immediately behind eyes (1).

11- Head not very strongly deflexed (0); head very strongly deflexed towards ventral face (1).

12- Mentum not concealing labial palpi (0); concealing at least basal half of labial palpi (1).

13- Lateral margins of mentum not converging posteriorly (0); converging posteriorly (1).

14- Lateral margins of mentum converging anteriorly (0); not converging anteriorly (1).

15- Gula well developed, only moderately narrowed anteriorly (0); gula forming a transverse triangle posteriorly, the gular sutures rather closely aggregated and parallel anteriorly, or even fused to a single median suture (1); gula absent, or appearing only as a very narrow transverse sclerite at the rear of the head (2). Additive.

16- Mandibles without appendage on inner face (0); with movable, articulated appendage on inner face (1 ).

421 17- Galea flattened forming a wide plate (0); galea almost circular in cross-section (1).

18- Galea with many setae in apical portion (0); only with few apical setae (1).

19- Setae of galea arranged in well defined rows (0); setae not arranged in rows, irregularly distributed (1).

20- Setae of galea curved apically towards middle (0); setae at most weakly curved, and not in one particular direction (1).

21- Apical segment of maxillary palpi at least as long as penultimate (0); shorter than penultimate (1).

22- Paraglossae (excl. setae) short, not reaching longer than midlength of 2nd segment of labial palpi (0); paraglossae longer, reaching at least to basis of 3rd segment of labial palpi (1).

23- 2nd segment of labial palpi without a row of setae on inner face (at most with 1-3 setae) (0); with a row (or longitudinal group) of setae on inner face (1).

24- Apical segment of labial palpi at least as wide as penultimate (0); distinctly narrower (1).

25- Apical segment of labial palpi wider than penultimate (0); not distinctly wider (1),

26- Apical segment of labial palpi with outer face more convex than inner face (0); almost symmetrical, outer and inner face equally convex (1).

27- Apical segment of labial palpi without spines (but often with setae) (0); with a group of fine spines (rather than setae) towards inner face (1).

28- Antennae at least c. 0.66 x as long as width of head (0); distinctly shorter (1).

29- Antennal pedicel not narrowed distally (0); conical, narrowed distally (1).

30- Antennal pedicel not wider than scape (0); distinctly wider (1).

31- Antennae with at least 3 intermediate segments (0); with less than three intermediate segments (1).

32- Antennae with less than five segments distal to cupule (0); with five segments distal to cupule (1).

33- Antennal segments distal to cupule forming a loosely segmented club (0); forming a more or less compact club (1).

34- Lateral margins of pronotum not forming a continuous curve with elytra (0); forming a continuous curve with elytra (1).

35- Pronotal surface uneven (0); surface even (1).

36- Pronotum without hyaline margins (0); with hyaline margins, at least laterally (1).

37- Posterior margin of pronotum with an accessory ridge (locking device) below the (freely exposed) margin (0); without such accessory ridge (1).

422 38- Accessory ridge below posterior pronotal margin narrow, less than 0.66 x as wide as pronotum at posterior margin (0); ridge wide, at least 0.66 x as wide as pronotum at posterior margin (1).

39- Accessory ridge below posterior pronotal margin not produced laterally into dentiform process (0); the ridge produced laterally into a small bluntly dentiform process (1).

40- Accessory ridge below posterior pronotal margin not distinctly continued laterally as an oblique-transverse fold (or a such is only detectable in less than medial half) (0); continued as a distinct ridge or fold at least halfway towards posterior pronotal corners (often almost reaching these) (1).

41- Prosternum well developed, its shortest length anterior to procoxae at least 0.1 x width (0); very short, shortest length less than 0.1 x width (1).

42- Prosternal process not or hardly widened at apex (usually ending well before hind margin of procoxae) (0); prosternal process long and widened behind procoxae, contacting the process of the hypomeron and thereby closing procoxal cavities posteriorly (1).

43- Prosternum rather weakly and almost regularly convex (0); prosternum tectiform (1); prosternum with strongly raised middle portion (2). Additive.

44- Prosternal process without apical notch (0); with a smaller or larger apical notch (1).

45- Procoxal cavities continued as a short slit anterolaterally, the slit less than 0.5 as wide as coxal cavity (0); continued anterolaterally in a longer slit, which is at least 0.5 x as wide as coxal cavity (1).

46- Hypomeron with anterior grooves for reception of antennal club (the grooves not extending over prosternum) (0); hypomeron without antennal grooves (except that prosternal antennal grooves may sometimes extend some distance across the hypomeron (1).

47- Mesosternum rather evenly convex, without raised carina or process (0); medially (at least posteriorly) ridged or raised to a dentiform process (1); raised to a well defined plate (“mesostemal tablet") (2). Additive.

48- Mesosternum wide anteriorly, at least 0.5 x as wide as anterior width of mesothorax (0); narrow anteriorly, less than 0.5 x as wide as anterior width of mesothorax (1).

49- Mesosternum distinctly demarcated from mesepisternae by fine sutures (0); fused with mesepisternae, not demarcated by fine sutures (except sometimes for indistinct vestiges of sutures ) (1).

50- 1st ventrite with rather smooth and even surface (0); 1st ventrite with uneven surface, with tubercles and grooves (1).

51- 1st ventrite less than 1.5 x as long as 2nd (0); at least 1.5 x as long as 2nd (1).

52- Posterior margin of 5th ventrite without stouter setae medially (0); posterior margin of 5th ventrite with a median fringe of stouter setae that are often situated in a minute apical emargination (1).

423 53- 6th and 7th ventrites retracted into abdomen (0); freely exposed (1).

54- Abdominal ventrites not separated by deep grooves (0); separated by narrow, deep grooves (1).

55- Anterior femora with hydrofuge (or at least rather dense) pubescence on ventral face, at least basally (0); without hydrofuge pubescence on ventral face (1).

56- Anterior femora rounded in cross-section, i.e. without (or only distally with) ventral ridge delimiting a tibial groove on inner face of the femur (0); with a ventral longitudinal ridge delimiting a tibial groove on inner face of femora in more than distal half (1).

57- Anterior femora without (or only distally with) dorsal ridge delimiting a tibial grrove on inner face of the femur (0); femora with a dorsal ridge (in addition to ventral ridge) delimiting a tibial groove on inner face of femora in more than distal half (1).

58- Anterior tibiae only slightly flattened, less than 1.5 x as wide as high (0); more strongly flattened, at least 1.5 x as w ide as high (1).

59- Anterior tibiae with the two series of spines nearest outer face well separated, not more closely aggregated than the others (0); the two series of spines on outer face of anterior tibiae closely aggregated (or even confluent), more closely aggregated than one of them s to other series of spines (1).

60- Anterior tibia with two of the apical spines (mediodorsally) distinctly (though sometimes only little) stouter than other spines at apex (0); without two stouter spines at apex (1).

61- Middle coxae globular or almost so, not more than 1.33 x as wide as long (0); more transverse, more than 1.33 x as wide as long (1).

62- Middle femora without hydrofuge pubescence (0); with more or less distributed hydrofuge pubescence basally (1).

63- Middle femur without series of fine spines on ventral face (0); with longitudinal series of small spines on ventral face (1).

64- Posterior coxae at most slightly narrowed laterally (0); markedly narrowed laterally (1).

65- Posterior femora not more than 4 x as long as wide (0); more than 4 x as long as wide (1).

66- Length of posterior femora less than 0.55 x width of 1st visible abdominal sternite (0); more than 0.55 x width of 1st visible abdominal sternite (1).

67- Posterior femora without hydrofuge pubescence (0); with more or less distributed hydrofuge pubescence basally (1).

68- Basal margin of posterior femur completely contacting the trochanter, i.e. without projecting angle (0); with anterobasal angle freely projecting, not contacting the trochanter (1).

69- Middle and posterior femora rounded in cross-section, i.e. without (or only distally with) ventral ridge delimiting a tibial groove on inner face of the femur (0); with a ventral longitudinal ridge delimiting a tibial groove on inner face of femora in more than distal half (1).

424 70- Middle and posterior femora without (or only distally with) dorsal ridge delimiting a tibial groove on inner face of the femur (0); femora with a dorsal ridge (in addition to ventral ridge) delimiting a tibial groove on inner face of femora in more than distal half (1).

71- Outer face of middle and posterior tibiae not crenulate-serrate (0); outer face of tibiae with two longitudinal (parallel) series of small and dense, acute tubercles, thus appearing crenulate-serrate (1).

72- The longest apical spur of middle and posterior tibiae distinctly longer than width of tarsus (0); not longer than width of tarsus (1).

73- Middle and posterior tarsi without long hairs on the ventral face (but normally with spines) (0); tarsi with some (or many) long fine hairs on their ventral face (in addition to spines) (1).

74- 2nd segment of middle and posterior tarsi (in forms with 5-segmented tarsi) longer than 1st (0); 2nd segment no longer than 1st (I).

75- Claw segment of all tarsi with empodium (0); without empodium (1).

76- With scutellary stria (at least detectable when the elytron is examined from below) (0); without any trace of scutellary stria, not even as a vestige when the elytron is examined from below (1).

77- Elytra without (or with only a few indistinct) coarse setiferous punctures (0); with distinct longitudinal series of coarse setiferous punctures (“systematic punctures’’) in 3rd, 5th, and 7th interstice (or, in species with non-striate elytra, at the homologous position) (1).

78- Elytra without longitudinal cuticular fold on ventral face (0); with a strong, longitudinal, sublateral cuticular fold (locking flange) on ventral face at the level of abdominal base, sometimes even reaching back to base of last ventrite (1).

79- Pseudepipleuron horizontal or only very slightly oblique (0); distinctly, often very oblique, or almost vertically hanging down in anterior third or more (1).

80- H in d w ing at least 1.5 x as long as elytron (0 ), less than 1.5 x as long as elytron (1).

81- Hind wing costa less than 1.5 x as long as apical portion of wing (0); at least 1.5 x as long as apical portion (1).

82- Hind wing costa more than 0.66 x as long as apical portion (0); less than 0.66 x as long as apical portion (1).

83- Widest part of hind wing lies proximal to (or at) M-Cu loop (or apex of pigmented part of Cu, in forms without M-Cu loop) (0); widest part distal to M-Cu loop (1).

84- Hind wing radius detectable proximal to r-m crossvein, and distinctly bifurcate proximally (0); radius distinctly proximal to r-m crossvein, but not bifurcate proximally (1); not distinctly proximal to r-m crossvein (2). Additive.

85- Hind wing with r-m crossvein rising from distal half of the pigmented area at anterior wing margin (0); rising from middle or from basal half (but no the base) of the pigmented area at anterior wing margin (1); rising from base of the pigmented area at anterior wing margin (2). A dditive.

425 86- Hind wing with M continued from m-cu loop towards base, distinct for some distance proximal to r-m crossvein (0); not distinct proximal to r-m crossvein (but still with distinct m-cu loop) (1); M reduced, so there is no distinct m-cu loop (2). Additive.

87- Hind wing with anal veins 1-4 (largely) all detectable, i.e both wedge cell and basal cell distinct (wedge cell however sometimes “open” towards posterior wing margin) (0); anal vein 4 reduced distal to basal cell, i.e. no distinct wedge cell (1); anal veins 1-4 all reduced (2). Additive

88- Hind wing with distinct jugal lobe (which is however not always demarcated from the remainder of the wing by an excision at posterior wing margin) (0); without jugal lobe (1).

89- Hind wing with jugal lobe demarcated from the remainder of the wing by a distinct excision at posterior wing margin (0); jugal lobe not demarcated from the remainder of the wing by an excision at posterior wing margin (1).

Characters of adults (males), from Hansen (1991):

90- 2nd and 3rd segments of anterior tarsi not dilated (0); 2nd and 3rd segments of anterior tarsi distinctly (sometimes strongly) dilated (1).

91- Aedeagus of a simple trilobed type, with distinct basal piece (0); aedeagus of a complex type, with basal piece apparently disappeared (1).

Characters of adults (females), from Hansen (1991):

92- 9th morphological abdominal sternite differing markedly from the preceding sternites, paired, and deflexed latero-dorsally towards the tergite (0); 9th morphological abdominal sternite simple, undivided, similar to the preceding sternites (1).

Additional adult characters, from Hansen (1991):

93- Head and pronotum with granulate sculpture (0); not granulate (1).

94- Pronotum not concealing head (0); pronotum with an anterior shelflike projection that conceals the head (in dorsal view) (1).

95- Apical segment of labial palpi without a subapical seta on outer surface (though sometimes with differently arranged setae) (0); apical segment of labial palpi with one (or a couple of very closely aggregated), long or rather long, subapical setae on outer face, otherwise without (or with few and more inconspicuous) setae (1).

96- Lateral (glabrous) portions of the hypomeron defined from the remainder (pubescent) portion by a sharp ridge (0); lateral portions well defined, but not demarcated by a ridge (1); lateral portions not defined (2). Additive.

97- Abdominal ventrites completely (or over most of the surface) with strong microsculpture and fine, dense (hydrofuge) pubescence (0); ventrites without strong microsculpture and dense (hydrofuge) pubescence (1).

426 APPENDIX D

Data matrix used for the analysis with adult characters:

TAXA CHARACTERS 1 11111111122222222223 3333333334 4444444445 1234567890 1234567890 1234567890 1234567890 1234567890

O c h t h e b i u s 0000000000 01110111-0 1001110010 1100011 --- 0000000-10 Helophoridae 0000100000 0000100000 0000000010 0000000111 0000000100 Epimetopidae 1000010000 1000000000 O O O O O O b O O a 0010000101 l a O O O O O l O O Georissidae 0000110001 1000200000 0100001000 0010000110 100-002001 Hydrochidae 0000100000 0000100000 0100000100 1010000101 0100000001 Spercheidae 0011001100 0001001101 0000100101 1000000010 1000010100 Sperchopsini l O O a O O l l l l O O O b O O O O l l a O b O l a O H O 0001100000 0000110100 Hydrophilina l a a O O O a l l l 0001000000 a O l O l O O O l O 0001100000 1 0 c a l l 2 1 0 0 Megasternini H O l O l a b l l O a a a O O O O l l a l O b l l O O l O a O l b b O O l O l b 0 c l 0 1 2 - 1 0

5555555556 6666666667 7777777778 8888888889 9999999 1234567890 1234567890 1234567890 1234567890 1234567

O c h t h e b i u s 0010100001 0010010000 0000100001 011 - 221-1 1100000 Helophoridae 0000000000 0000000000 O O O O O a a O O l 0010000000 0010000 Epimetopidae O O O O l O a O O O O O O a O b O O O O 1100000000 0010000000 0-11001 Georissidae 10011101-1 0001110010 1 1 0 0 1 1 0 1 -0 0112110.010 0011000 Hydrochidae 1101000000 0101111000 0100010100 0010000000 0010100 Spercheidae 0000000000 0100001000 1101010001 1002000010 0000000 Sperchopsini O a O O O b b O l O H O O O O l l b b O O l O O a a O l - 0000100000 O O O O b l O Hydrophilina O b O O O l O a b O l b O O O O b l l l 0000001011 1000000010 0 0 0 0 1 1 a Megasternini l O O O O l l b l O l O O O O a O l b b O a b l O l O O b O 0 0 1 d d b l l - 0 0 0 0 0 0 1 a

Definitions

- = character does not apply to that taxon a = multistate character for t h a t t a x o n (0/1), 0 is supposed to b e ancestral and 1 derived. b = multistate character for t h a t t a x o n ( 1 / 0 ) , 1 is s u p p o s e d to b e ancestral and 0 derived. c = multistate character for t h a t t a x o n (1/2), 1 is s u p p o s e d t o b e ancestral and 2 derived. d = multistate character for t h a t t a x o n (2/1), 2 is s u p p o s e d t o b e ancestral and 1 derived. ? = data not available for that taxon.

427 APPENDIX E

Data matrix used for the combined analysis:

TAXACHARACTERS

1 11111111122222222223 3333333334 1234567890 1234567890 1234567890 1234567890

O c h t h e b i u s 0000000000 0000000001 0000100001 0010000000 Helophoridae 1100110110 1011211010 1111011200 0100100001 Epimetopidae 1110110110 1011210011 1111011200 1100710000 Georissidae ???0110110 1011111010 1111011200 1100700001 Hydrochidae 0 1 0 1 1 2 1 7 1 0 2010210011 0012111210 1101700001 Spercheidae 1111121110 2000210011 0102110110 1 1 0 1 7 0 0 1 1 0 Sperchopsini 1101121111 2111110011 0112011110 H O l l l O O a O Hydrophilina 1 1 0 1 1 2 1 1 1 a 2111110111 0112011110 H O l l l a a O O Megasternini 1101121111 2111210111 0112011110 1 101111010

4444444445 5555555556 6666666667 7777777778 88888 1234567890 1234567890 1234567890 123456789012345

O c h t h e b i u s 0000001110 111-010011 1001011000 1 1 -0 0 0 0 0 00-10 Helophoridae 0000000001 0000000000 0001000000 0011100000 00100 Epimetopidae 1000010000 0000000000 O b O O a O O l O O O O l O l l a O O O 00100 Georissidae 1000110002 0000001000 0100000100 00110100-0 02001 Hydrochidae 0000000001 0000001000 0010010100 0010101000 00001 Spercheidae 0110000010 0110100001 0010110000 0001010000 10100 Sperchopsini O l l l l O O O b O O O O l l a O b O l a O U O O O O l l 0000000001 10100 Hydrophilina O a l l l O O O l O O O O O O a O l O l 0001000011 O O O O O l O c a l 12100 Megasternini l a b l l O a a a O O O O l l a l O b l l O O l O a O l b b O O l O l b O c l O 12-10

428 111111 1111111111 1111111111 1111111 8888999999 9999000000 0000111111 1111222222 2222333 6789012345 6789012345 6789012345 6789012345 6789012

O c h t h e b i u s 0010100001 0010010000 0000100001 011-- 221-1 1100000 Helophoridae 0000000000 0000000000 O O O O O a a O O l 0010000000 0010000 Epimetopidae O O O O l O a O O O O O O a O b O O O O 1100000000 0010000000 0-11001 Georissidae 10011101-1 0001110010 11001101-0 0112110010 0011000 Hydrochidae 1101000000 0101111000 0100010100 0010000000 0010100 Spercheidae 0000000000 0100001000 1101010001 1002000010 0000000 Sperchopsini O a O O O b b O l O H O O O O l l b b O O l O O a a O l - 0000100000 O O O O b l O Hydrophilina O b O O O l O a b O l b O O O O b l l l 0000001011 1000000010 0 0 0 0 1 1 a Megasternini l O O O O l l b l O l O O O O a O l b b O a b l O l O O b O 0 0 1 d d b l l - 0 0 0 0 0 0 1 a

Definitions

- = character does not apply to that taxon a = multistate character for t h a t taxon (0/1), 0 is supposed to be ancestral and 1 derived. b = multistate character for t h a t taxon (1/0), 1 is s u p p o s e d t o b e ancestral and 0 derived. c = multistate character for that taxon (1/2), 1 is s u p p o s e d to b e ancestral and 2 derived. d = multistate character for that taxon (2/1), 2 is s u p p o s e d t o b e ancestral and 1 derived. ? = data not available for that taxon.

429 APPENDIX F

Mickevich & Farris Incongruence Metric (1981):

Preimaginal Adult Combined

# of characters 36 97 132

# o f synapomorphies 42 104 146

Length of tree 51 177 236

Extra steps 9 73 90

IM = . ESc - [ESI + ESa] CS

90-[73+ 9] = 0.034 236

IM = Incongruence metric ESc = Extra steps of the combined tree ESI = extra steps of the tree from characters from immature stages ESa = extra steps of the tree from adult characters CS = total steps of the tree from the combined matrices

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