AN ABSTRACT OF THE THESIS OF Loren Kenneth Russell for the degree of Doctor of Philosophy in Department of Entomology presented on May 11, 1979 Title: A Biological and Systematic Study of the Armored Boreid, Caurinus dectes, with Comparative Notes on Related Mecoptera Redacted for privacy Abstract approved: . Lattin Caurinus dectes Russell is a minute, brachypterous scorpionfly which was discovered at Marys Peak, Benton County, Oregon, in 1976, and subsequently described as the only representative of the subfamily Caurininae within the Boreidae (snow scorpionflies). Caurinus dectes is now known to range from the Olympic Peninsula and Northern Cascades in Washington, to northern Lane County, Oregon. The habitats of C. dectes include moist, forested sites with both coniferous and deciduous canopies. Larvae and adults have been found in bryophytes occurring as epiphytes, or on logs and stumps, and in terrestrial stands of mosses and liverworts. Feeding studies showed that both adults and larvae of Caurinus are specialized feeders on leafy liverworts (Jungermanniales). Twenty-five species of Jungermanniales in 15 genera were highly acceptable to adults, while 11 species in 10 genera were accepted slightly, if at all. Adults of C. dectes fed to some degree on two of four genera of the thalloid Metzgeriales, while liverworts of the Marchantiales and Anthocerotae were not accepted at all. Larval feeding preferences paralleled those of adults. The eggs of C. dectes are glued to the leaves of the host liverworts. Eggs hatch in spring, but some eggs may remain in diapause for a year or more. Larval feeding is within the shoot tissues, and is completed within 2 to 3 months of eclosion. There appear to be 3 larval instars. The fully grown larva constructs a silk-lined pupal cell within or under the substrate. The pupal molt occurs between July 1and August 15, adult emergence is between September 1and October 15. The major period of adult activity extends from eclosion to April. Mating and oviposition may occur through most of this period. There is evidence that some fraction of the adult population may perenniate. The univoltine life cycle, probable perenniation of adults, and extended egg diapause all are unusual within the Boreidae. The external morphology of larva and pupa, and internal and external morphology of adults are described. The larva is curculioniform, as compared with the scarabaeiform larvae of other Boreidae; the pupa is decticous and exarate. The most aberrant structures of adult Caurinus (cf. other Boreidae), the short rostrum and retractable postabdomen of the female, are probably adapted to the dorsoventral organization of the host liverworts. C. dectes is highly specialized, but a number of characters are primitive with respect to other boreids. These characters justify the recognition of Caurinus as the sister- group of all other boreids. Certain characters of C. dectes, including the free cerci of the female, support the view that the Boreidae are not closely related to other mecopteran families. A Biological and Systematic Study of the Armored Boreid, Caurinus dectes, with Comparative Notes on Related Mecoptera by Loren Kenneth Russell A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Completed May 11, 1979 Commencement June 1980 APPROVED: Redacted for privacy Professor of Elltothology ln charge of major Redacted for privacy Head of Department of Entomology Redacted for privacy Dean of Graduate School Date thesis is presented May 11, 1979 Typed by Judy Russell for Loren Kenneth Russell ACKNOWLEDGEMENTS AsI look over the odd career of my association with Oregon State University, the construction of proper thanks becomes a slippery matter. It is fitting, however, to note first my gratitude to Paul Johnson, Kenneth Cooper, and Paul Ritcher, who made this study possible in my mind, and to J. D. Lattin for taking on this uncertain prospect. I am also appreciative of the other members of my thesis committee: G. W. Krantz, N. H. Anderson, J. H. Lyford, F.R. Rickson, P. Oman, G. R. Ferguson, and P. S. Dawson. Dr. Oman, in particular, came in late in this study, and put a great deal of time into working with my manuscript. I have incorporated in this text comments, ideas, and data provided by a number of my colleagues. I have attempted to identify the sources of such information, The following contributors deserve special mention here: Kenneth Cooper, Department of Biology, University of California, Riverside; Miriam Rothschild, Peterborough, England; William Fender, Corvallis, Oregon; David Wagner, Department of Biology, University of Oregon, Eugene; N. H. Andersen, Department of Chemistry, University of Washington, Seattle; and Gerhard Mickoleit, University of Tubingen, Germany. I am further indebted to many individuals who have aided in this study: Gary Peters and Paul Johnson (field assistance and data); Kermit Cromack (nutrient analysis of bryophytes); Bo Addison and Dave Voegtlin (scanning electron microscope operation); Jean De Haven (histological preparation); Wayne Mathis (assistance with literature); Jim Cornell, Al Allen, George Byers, and Baldo Villegas (specimens of Mecoptera); Glenn Juday (habitat search); Dave Wagner and Jack Lyford (determination of liverworts and mosses, respectively); Abe Hindawi and Harold Bond (access to laboratory facilities). A tremendous amount of time was invested by Judy Russell in typing, correcting, and editing successive drafts of this dissertation. The study at Marys Peak was carried out under a Special Use Permit through the courtesy of the Alsea Ranger District, United States Forest Service. Finally, my supervisor, Nelson Pettit, and employers, Northrop Services Inc, of Corvallis, have provided some support and consideration during my study. TABLE OF CONTENTS I. Introduction 1 Specific Identity of Caurinus 5 II. Methods 8 Collection and Recovery 8 Wet-screening 9 Tuligren Funnel Operation 13 Direct Search 13 Culture Methods 14 III. Geographic Distribution of Caurinus 18 Elevation Range 19 Climatic Factors 20 Discussion 21 Effect of Pleistocene Glaciation 23 IV. Habitat of Caurinus dectes 37 Topography and Soils 38 Vegetation 38 Distribution of Caurinus Host Substrates 42 Distribution of Caurinus dectes in Relation to Plant Communities and Succession 44 Other Caurinus Populations 47 Other Coastal Populations 49 Populations in Washington 50 Crown Point Population 51 V. Feeding Biology of Caurinus dectes 64 Liverwort Survey 65 Feeding Tests - Adult and Larval Caurinus 66 Results of Feeding 72 Epiphytic Hepatics 83 Hepatics Growing on Logs and Stumps (xylicoles) 83 Hepatics Occurring on Rock Surfaces 84 Terrestrial Hepatics 85 Aquatic Hepatics 85 Discussion 85 VI. Behavior 91 Adult Feeding Behavior 91 Diurnal Cycle 95 Grooming Behavior 96 Antenna Cleaning 97 Cleaning of the Head and Mouthparts 99 Cleaning of the Legs 99 Cleaning of the Abdomen 100 Other Cleaning Behavior 100 VII, Life History of Caurinus dectes 103 Egg 103 Oviposition 104 Egg Hatching 106 Fecundity 109 Larvae of Caurinus - Behavior 112 Locomotion 112 Larval Feeding 113 Larval Feeding in Other Boreids 115 Molting 116 Post-feeding Larvae and Pupa 116 Construction of the Pupal Cell 117 Developrient of the Pharate Pupa 122 Pharate Adult and Eclosion 123 Adult Eclosion 123 Mortality Factors 125 Phenology 127 VIII. Larval Morphology 138 Description of Full-grown Larvae of Caurinus dectes 138 Color 138 Texture 138 Head 139 Thorax and Abdomen 141 Discussion 142 Comparison of Caurinus Larvae with Other Mecoptera 143 Epistomal Suture 146 Larval Eyes 147 Antennal Segmentation 148 Labium and Hypopharynx 149 The Eleventh Abdominal Segment 149 Number of Larval Instars in Caurinus 160 IX. Morphology of the Pupa 169 Description of the Pupa of Caurinus'dectes 169 X. Adult Morphology 174 Internal Anatomy - Methods of Study 174 Internal Anatomy of Adults of Caurinus dectes 175 The Digestive System 176 The Salivary (Labial) Glands 176 The Foregut (Stomodeum) 176 The Midgut (Mesenteron) 179 Hindgut (Proctodeum) and Malpighian Tubules 180 The Central Nervous System 181 The Male Reproductive System 182 The Female Reproductive System 185 The Tracheal System 186 XI. The Skeletomuscular System 193 The Head 193 Cranial Endoskeleton 196 The Mandibles 196 The Maxillae 197 The Labium 199 Muscles of the Maxillolabial Complex 206 Mouthpart Function 207 The Thorax 209 Cervix 210 Prothorax 210 Pterothorax 210 The Wing Mechanism in Male Caurinus dectes 211 Locomotion 215 The Abdomen 217 Male Genitalia 221 Anatomical Correlations During Mating 224 Discussion 225 The Spermatophore 228 Female Postabdomen 230 Mating Behavior of Caurinus dectes 236 Discussion of Mating Behavior 238 Cytology 243 XII. Discussion and Conclusion 246 Phylogenetic Position of Caurinus 247 Relationship of Boreidae to other families of Mecoptera 249 XIII. Bibliography 253 XIV. Appendices I. An Annotated List of Bryophagous Insects and Mites in Western Oregon and Western Washington262 II. Index to Plant and AnimalTaxa 272 LIST OF ILLUSTRATIONS Figure Page 1 Female Caurinus dectes, lateral aspect 2 2 Male C. dectes, dorsal aspect 2 3 Male C. dectes, frontal aspect 2 4 Epiphytic moss on lower branches of western hemlock 53 5 Epiphytic bryophytes( Porella- Metaneckera) 53 associations on arched stems of vine maple 6 Open grove of red alder and bigleaf maple with 53 old coniferous windthrow in foreground 7 Logs in depression, bearing Scapania bolanderi 55 and Calypogeja associations 8 Close-up of Scapania bolanderi growing near base 55 of decorticated red cedar stump 9 Base of mature red alder in open grove with 57 abundant Porella-Frullania epiphytic association 10 Close-up stem shown in Figure 9 57 11 Logging debris in small tributary of Mulkey Creek 57 12 Habitat of C. dectes in stream corridor at Depot 59 Creek 13 Tangle of vine maple near Siletz, Oregon 59 14 Terrestrial Gyrothyra underwoodiana association 61 growing on clay of north-exposed road bank 15 Gyrothyra underwoodiana and Diplophyllum 61 taxifolium growing on soil 16 Bog at head of stream (Klickitat Mountain) 61 17 Habitat of C. dectes in southwestern Washington.