AN ABSTRACT OF THE THESIS OF CHARLES WILLIAM BAKER for the Ph. D. in Entomology (Name) (Degree) (Major) Date thesis is presented 4ila-as t` :;2,/9c, Title LARVAL SYSTEMATICS OF THE TROGINAE IN NORTH AMERICA WITH NOTES ON BIOLOGIES AND LIFE HISTORIES (COLEOPTERA: SCARABAEIDAE). Abstract approve Major professor A study of the immature stages of the subfamily Troginae in North America was conducted from the spring of 1963 through the spring of 1965, Larvae of Trox and Omorgus were easily reared in the laboratory, but all attempts to rear the larvae of Glaresis were unsuccessful, The suberosus group, one of the five groups of species within the genus Trox in North America as recognized by Vaurie (1955), is given generic status. The 17 species of the suberosus group are placed in the genus Omorgus which was originally proposed by Erichson (1847) with Trox suberosus later designated as the type. The placement of these 17 species in Omorgus is done on the basis of the larval morphology and recent work on the morphology and cyto- genetics of the adults. A table listing 17 characters by which the genus Trox may be distinguished from the genus Omorgus is pre- sented. The other four groups of species in North America, as recognized by Vaurie (1955), are retained in the genus Trox. The adults of 22 species of Trox and Omorgus were collected during the summers of 1963, 1964, and 1965, in the states of Oregon, Arizona, New Mexico, and Texas. Cultures of these beetles were established in the laboratory and 595 larvae were reared for the systematic studies of the immature stages. Additional material was borrowed from the U. S. National Museum and Dr. P. O. Ritcher, and the larvae of two species were used for the descriptions. Generic descriptions of the larvae of Trox and Omorgus are given along with brief descriptions of 24 of the 42 species of these genera known to occur in North America. The larvae of the following species are described: T. scaber (L. ), T. aequalis Say, T. fascifer LeConte, T. atrox LeConte, T. spinulosus dentibius Robinson, T. foveicollis Harold, T. frontera Vaurie, T. sonorae LeConte, T. robinsoni Vaurie, T. tuberculatus (De Geer), T. plicatus Robinson, T. sordidus LeConte, T. variolatus Melsheimer, T. unistriatus Beauvois, O. suberosus (Fabricius), O. rubricans (Robinson), O. carinatus (Loomis), O. monachus (Herbst), O. fuliginosus (Robinson), O. asper LeConte, O. punctatus (Germar), O. inflatus (Loomis), O. texanus LeConte, O. scutellaris (Say). The general life history of Trox scaber (L. ) as it occurs in the laboratory is described and notes on other species are included. A section on the general biology of Trox and Omorgus is given. The method whereby the immature stages of Trox and Omorgus were reared is described. Pertinent morphological characters of the im- mature stages are presented in 59 figures, and the literature of the immature stages reviewed on a worldwide basis. A key to the third stage larvae is given, but larvae of several closely related species were inseparable and are keyed out in the same couplet. Structures of taxonomic importance include the epi- pharynx, hypopharynx, antennae, head capsule setation and topog- raphy, maxillae, spiracles, and setal and spinule patterns on the thoracic and abdominal lobes and legs. A simplified terminology is utilized for reference to the lobes of the abdominal and thoracic regions. The terms subtorma, subapotorma, and fused phobal mass are proposed to facilitate the description of the larval hypopharynx and epipharynx. A synoptic collection of the larvae utilized in this study has been deposited in the collection of the U. S. National Museum, Washington, D. C. LARVAL SYSTEMATICS OF THE TROGINAE IN NORTH AMERICA WITH NOTES ON BIOLOGIES AND LIFE HISTORIES (COLEOPTERAN SCARABAEIDAE). by CHARLES WILLIAM BAKER A THESIS submitted to OREGON STATE UNIVERSIT Y in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY June 1967 APPROVED: Professor and Chairman of Department of Entomology In Charge of Major De of raduate School Date thesis is presented A.A./s-T , /966 Typed by Nancy Kerley ACKNOWLEDGEMENT The writer wishes to express his sincere gratitude to all those persons who assisted him during the course of this study. A special debt of gratitude is owed to the following: Dr. Paul O. Ritcher who suggested the topic, provided the assistantship, and gave liberally of his time and energies in the capacity of major professor. Dr, J, D, Lattin, Dr, C. H, Martin, Dr. F. H. Butt, and other members of the entomology department for their advice and encouragement. Mrs. P. Vaurie, American Museum of Natural History, for the loan and exchange of adult specimens. Mr. O. L. Cartwright and Mr. D. M. Anderson, U. S. National Museum, for the exchange of adult specimens and the loan of adults and immatures. Mr. L. J. Bottimer, Kerrville, Texas; Dr. M. A. Cazier and Mr. M. A. Mortenson, Portal, Arizona; Dr. C. Cottam, Rob and Bessie Welder Wildlife Foundation, Sinton, Texas; Dr. R. O. Drummond and Dr, O. H. Graham, Entomology Research Division, U. S. D. A. , Kerrville, Texas; Dr. R. I. Gara, Boyce Thompson Institute Forest Research Laboratory, Beaumont, Texas; Mr, E. L. Pond, San Pedro Ranch, Carrizo Springs, Texas; and Mr. V. D. Roth, Southwest Research Station, American Museum of Natural History, Portal, Arizona for the hospitality and assistance that they rendered during the collecting trip through Arizona, New Mexico, and Texas during the summer of 1964, Mr. L. J. Bottimer, Dr, R. I. Gara, Mr. N. McFarland, Dr. F. D. Parker, and Dr. L. A. Stange for their interest in the study and the collection and shipment of numerous live adults to the writer. Mr. J. F. Cornell, Mr, R, K. Eppley, Mr, K. Goeden, Mr, D. L. Mays, Mr. C. E. Osgood, Dr. R. L. Rabb, Dr. S. Radinovsky, Dr. W. P. Stephen, and Mr. J. R. A. Willard for assistance in the collection of adults and larvae. Dr. N. Virkki, University of Puerto Rico, Agricultural Experiment Station, for his studies of the spermatogenesis and chromosomes of Trox and Omorgus. Dr. O. Zethner-Moller and Mr, W. H. C. Schallig for their kind assistance in the translation of foreign papers. Mr. P, Schilling and the genetics department for their help in attaining insecticide -free foodstuffs for the beetles. Mr. David R. Smith for his assistance in the investigation of many malodorous carcasses on the collecting trip during the summer of 1964. TABLE OF CONTENTS Page I. INTRODUCTION 1 II. LITERATURE REVIEW 5 Incertae Sedis 10 III. SYSTEMATIC SECTION 11 IV. METHODS AND MATERIALS 17 Collection of Specimens 17 Preservation of Specimens 19 Rearing of Immature Stages 20 Preparation and Study of Specimens 21 Terminology 23 Illustrations 25 V. GENERAL BIOLOGY 27 VI. GENERAL DESCRIPTION OF IMMATURE STAGES 31 VII. LIFE HISTORY 34 VIII. KEYS TO THE THIRD STAGE LARVAE 38 Key to the Genera 38 Key to the Known Third Stage Larvae of Trox 39 Key to the Known Third Stage Larvae of Omorgus 43 IX. GENERIC DESCRIPTION OF TROX LARVAE 45 X. SPECIES DESCRIPTIONS OF TROX LARVAE 52 Trox fascifer LeConte 52 Trox scaber (Linnaeus) 54 Trox aequalis Say 56 Trox atrox LeConte 58 Trox spinulosus dentibius Robinson 60 Trox foveicollis Harold 62 Trox frontera Vaurie 64 TABLE OF CONTENTS (continued) Page Trox robinsoni Vaurie 66 Trox plicatus Robinson 68 Trox tuberculatus (De Geer) 70 Trox sonorae LeConte 72 Trox variolatus Melsheimer 74 Trox sordidus LeConte 76 Trox unistriatus Beauvois 78 XI. GENERIC DESCRIPTION OF OMORGUS LARVAE 80 XII. SPECIES DESCRIPTIONS OF OMORGUS LARVAE 87 Omorgus suberosus (Fabricius) 87 Omorgus fuliginosus (Robinson) 89 Omorgus monachus (Herbst) 91 Omorgus asper LeConte 93 Omorgus inflatus (Loomis) 95 Omorgus punctatus (Germar) 97 Omorgus carinatus (Loomis) 99 Omorgus scutellaris (Say) 101 Omorgus rubricans (Robinson) 103 Omorgus texanus LeConte 105 XIII. SUMMARY 107 109 XIV. BIBLIOGRAPHY SYMBOLS USED ON FIGURES 114 FIGURES 118 LIST OF FIGURES Figure Page 118 1 Trox unistriatus Beauvois. Head 2 Trox variolatus Melsheimer. Epipharynx. 118 120 3 Trox scaber (Linnaeus). Epipharynx. 4 Trox sonorae LeConte. Epipharynx. 120 120 5 Trox spinulosus dentibius Robinson. Epipharynx. 120 6 Trox aequalis Say. Epipharynx. ? Trox unistriatus Beauvois. Epipharynx. 120 8 Trox fascifer LeConte. Epipharynx. 120 122 9 Omorgus scutellaris (Say). Epipharynx. 10 Omorgus rubricans (Robinson). Dorsal aspect of labium and hypopharynx. 122 122 11 Omorgus suberosus (Fabricius). Epipharynx. 12 Omorgus carinatus (Loomis). Dorsal aspect of labium and hypopharynx. 122 13 Omorgus monachus (Herbst). Ventral aspect of abdominal segment 8 of female pupa. 122 14 Omorgus monachus (Herbst). Ventral aspect of abdominal segment 8 of male pupa. 122 15 Trox tuberculatus (De Geer). Egg bursters from dorsum of mesothorax and metathorax. 122 16 Trox frontera Vaurie. First stage larva. 124 17 Trox frontera Vaurie. Second stage larva. 124 18 Trox frontera Vaurie. Third stage larva. 124 LIST OF FIGURES (continued) Figure Page 19 Trox sordidus LeConte. Dorsal aspect of labium and hypopharynx. 124 20 Trox sonorae LeConte. Second and third segments of antenna. 124 21 Omorgus asper LeConte. Second and third segments of antenna. 124 22 Trox sonorae LeConte. Lateral aspect of segments 7, 8, 9, and 10 of abdomen. 124 23 Trox and Omorgus eggs. A. Omorgus texanus LeConte B. Trox scaber (Linnaeus). C. Trox atrox LeConte. D. Trox sonorae LeConte. E. Omorgus monachus (Herbst). 126 24 Omorgus monachus (Herbst). Head. 126 25 Omorgus texanus LeConte. Head. 126 26 Omorgus inflatus (Loomis). Dorsal aspect of galea and lacinia. 27 Omorgus punctatus (Germar). Anterior aspect of left matathoracic leg. 126 28 Omorgus carinatus (Loomis). Ventral aspect of segment 2 of abdomen. 126 29 Omorgus fuliginosus (Robinson). Lateral aspect of thorax. 128 30 Omorgus monachus (Herbst). Prothoracic leg of pupa.