THE awrmmv Q? NQRTH AMERECAN LEPEDOCYRTUS? S. 3112., (EZWMBQLA 1 EN?©£%@ERWE§§) Titus: {av {'Ew Dogma 42$ M. 5. MCKEGAN STATE UKEE’ERSETY Richard J. Snider 1.967 THESL-fi ” ' mi LIB R A R Y ‘- Michigan State. University ABSTRACT THE CHAETOTAXY OF NORTH AMERICAN LEPIDOCYRTUS S. STR., (COLLEMBOLA:ENTOMOBRYIDAE) by Richard J. Snider This work is a comparative morphological study of the macro- and microchaetae occurring on members of the genus Lgpidocyrtus Bourlet. A metfihd for mounting cleared exoskeletons of specimens to be studied is given. Tables of comparative macro- and microchaetal patterns are included. Descriptions of fourteen species with illustrations of their chaetotaxal patterns form the main study. Three species are described as new and two new combinations are identified. THE CHAETOTAXY OF NORTH AMERICAN LEPIDOCYRTUS S. STR., (COLLEMBOLA:ENTOMOBRYIDAE) BY Richard J. Snider A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Entomology 1967 ACKNOWLEDGMENTS I wish to thank the members of my committee: Dr. Roland Fischer committee chairman, Department of Entomology; Dr. Gerald Prescott, Department of Botany; Dr. Fredrick Stehr, Department of Entomology; and Dr. T. Wayne Porter, Department of Zoology for their kind coopera— tion during the writing of this thesis. Special thanks are extended to: Dr. James Butcher, Department of Entomology, for consultation and encouragement; Dr. Kenneth Christiansen, Grinnell College, for aid in limiting and outlining the thesis topic; Dr. Hermann Gisin, Museum d'Histoire Naturelle de Geneve, for his criticism and additional suggestions; Dr. Harlow B. Mills, Chief (ret.), the Illinois Natural History Survey, for many years of aid and understanding. Finally, I want to thank my office partners, James Shaddy and Jon Maki, for perseverance while this thesis was being completed. ii TABLE OF CONTENTS Page ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . ii LIST OF TABLES O O O O O O O O O O O O O O O O O O O O O O O O 0 LIST OF PLATES O O O O O O O O O O O O O O O O O O O O O O O 0 INTRODUCTION 0 O O O O O O O O O O O O O O O O O O O C O C O C O 1 MATERIALS AND METHODS O O O O O O O O O C O O O O O O O O O O I S CHAETOTAXY O O O O O O O O O O O O O O O O O O O O O O O O O O O 8 I. The Macrochaetal Pattern . . . . . . . . . . . . . . . . 8 II. The Microchaetae (Accessories) Associated with the Lateral Lasiotrichia of Abdomen III . . . . . . . 13 III. The Microchaetae (Accessories) Associated with the Anterior Lasiotrichia of Abdomen IV . . . . . . . 15 CHAETOTAXY OF NORTH AMERICAN SPECIES . . . . . . . . . . . . . . 16 Group "A" . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Lepidocyrtus lignorum . . . . . . . . . . . . . . . . . . . l6 Lepidocyrtus unifasciatus . . . . . . . . . . . . . . . . . l7 Lepidocyrtus finensis . . . . . . . . . . . . . . . . . . . l7 Lepidocyrtus curvicollis . . . . I . . . . . . . . . . . . . 18 Lepidocyrtus neofasciatus . . . . . . . . . . . . . . . . . l8 Lepidocyrtuspparadoxus . . . . . . . . . . . . . . . . . . . l9 Lepidocyrtus violaceous . . . . . . . . . . . . . . . . . . 20 Group "B" . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Lepidocyrtus cinereus . . . . . . . . . . . . . . . . . . . 20 Lepidocyrtus lanuginosus . . . . . . . . . . . . . . . . . . 2l Lepidocyrtus heleni . . . . . . . . . . . . . . . . . . . . 22 Lepidogyrtus millsi . . . . . . . . . . . . . . . . . . . . 24 Lepidocyrtus floridensis . . . . . . . . . . . . . . . . . . 26 Lepidocyrtus pallidus . . . . . . . . . . . . . . . . . . . 28 Lepidocyrtus cyaneus . . . . . . . . . . . . . . . . . . . . 28 SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 LITERATURE C ITED O O O O O O O O O O O O O O O O O I O O O O O O 3 1 PLATES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 iii LIST OF TABLES Table Page 1. Groups of Species for North American Lepidocyrtus Based on the Numbers of Medial Macrochaetae of ABD IV 0 O O O O O O O O O O O O O O O O O O O I O C O 10 2. Lateral Macrochaetotaxal Formulae of Abdominal Segment III of Lepidocyrtus . . . . . . . . . . . . . . 11 3. Macrochaetotaxal Formulae of Abdominal Segment IV of Lepidocyrtus . . . . . . . . . . . . . . . . . . . . 12 4. Table of Comparative Formulae for Microchaetae (Accessories) of ABD III of Lepidocyrtus . . . . . . . 14 iv LIST OF PLATES Page PLATE I O O C O O O C O O O C O O O I O O O O O O O O O O O O I 3 5 Fig. l. Macrochaeta Fig. 2. Lasiothrichium Fig. 3. Pseudopore Fig. 4. Dorsal Composite View of Lepidocyrtus PLATE II 0 O O O O O O O O O O I O O I C I O O l O O O O O C O O 3 7 Fig. 5. 'L. lignorum, Dorsal Macrochaetae Fig. 6. .L. unifasciatus, Dorsal Macrochaetae Fig. 7. .L. finensis, Dorsal Macrochaetae PLATE III 0 O O O O I O O O O O O O O O O O O O O O O O O C C I 3 9 Fig. 8. .L° curvicollis, Dorsal Macrochaetae Fig. 9. IL. neofasciatus, Dorsal Macrochaetae Fig. 10. L. paradoxus, Dorsal Macrochaetae PIATE IV 0 O C O 0 O C O I O O C O O O O O O O O O O O O O O O C 1+ 1 Fig. 11. .L. violaceous, Dorsal Macrochaetae Fig. 12. ‘L. cinereus, Dorsal Macrochaetae Fig. 13. .L- lanuginosus, Dorsal Macrochaetae PLATE V . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Fig. 14. .L' heleni, Dorsal Macrochaetae Fig. 15. 'L. millsi, Dorsal Macrochaetae Fig. 16. .L. floridensis, Dorsal Macrochaetae PI‘ATE VI 0 O C I O O I O O I O O O O O O O O O O O O O O O C O O 45 Fig. 17. L. pallidus, Dorsal Macrochaetae Fig. 18. ,L. cyaneus, Dorsal Macrochaetae PLATE VII . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Fig. 19. ‘L. lignorum, Microchaetae of ABD III Fig. 20. .L. unifasciatus, Microchaetae of ABD III Fig. 21. ‘L. finensis, Microchaetae of ABD III Fig. 22. .L- curvicollis, Microchaetae of ABD III V Fig. Fig. 23. 24. PLATE VIII . Fig. Fig. Fig. Fig. Fig. Fig. PLATE IX . Fig. Fig. PLATE X Fig. Fig. Fig. Fig. PLATE XI. Fig. Fig. Fig. Fig. Fig. Fig. Fig. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. Q*k* lrflyflpflyflpdp* IHIH .L. lignorum, unifasciatus, finensis, neofasciatus, violaceous, cinereus, Eallidus, Microchaetae of ABD III cxaneus, Microchaetae of ABD III heleni, millsi, Microchaetae of ABD IV .L- paradoxus, floridensis, Microchaetae of ABD IV L. curvicollis, Microchaetae of ABD IV L. lanuginosus, cyaneus, Microchaetae of ABD IV Lepidocyrtus heleni n. 37. 38. 39. 40. 41. 42. 43. PLATE XII. Fig. Fig. Fig. Fig. Fig. Fig. Fig. 44. 45. 46. 47. 48. 49. 50. Dorsal Habit Tenaculum Lateral Habit Mucro Claw Eye Patch Antenna SP Lepidocyrtus millsi, n. Dorsal Habit Tenaculum Lateral Habit Mncro Claw Eye Patch Antenna sp. violaceous, Microchaetae of ABD III cinereus, Microchaetae of ABD III lanuginosus, Microchaetae of ABD III heleni, Microchaetae of ABD III millsi, Microchaetae of ABD III floridensis, Microchaetae of ABD III neofasciatus, Microchaetae of ABD III Earadoxus, Microchaetae of ABD III Page 49 51 53 55 57 Page PLATE XIII. Lepidocyrtus floridensis, n. sp. . . . . . . . . . 59 Fig. 50. Lateral Habit Fig. 51. Tenaculum Fig. 52. Dorsal Habit Fig. 53. Antenna Fig. 54. Eye Patch Fig. 55. Claw Fig. 56. Mucro vii INTRODUCTION The problems involved in making generic and specific determina- tions of some members of the order Collembola 3go‘- finding reliable morphological key characters to separate them one from the other. The small size of Collembola forced early workers to restrict their obser- vations to limited anatomical differences and color patterns. When Sir John Lubbock (1873) published his great monograph on the Apterygota, a more organized and exacting approach to the study of Collembola began. He observed and recorded, both in text and figures, minute structures omitted by earlier taxonomists. The detailed comparative systematic pursuit of the order was initiated at the beginning of the 20th century with the work of Carl Borner (1901 and 1906) and until recently has not changed significantly. The first advances in chaetotaxy began with Bonet (1945), who described the chaetotaxy of the head of some species of Hypogastrura. Delamare-Debouttville (1951) surveyed the known information on macro- chaetae and trichobothria associated with soil-type Collembola and related these structures to phylogeny. Yosii (1956) described the basic chaetotaxy of the Hypogastruridae and distinguished each seta of the head and body segments. Cassagnau (1959) discussed the distribu- tion of macrochaetae on the tergites of Tetracanthella. He stated that the position of the macrochaetae was of great systematic importance. Using chaetotaxic patterns he was able to divide Tetracanthella into three chaetotaxic types. In his revision of the genus Entomobrya, 1 2 Christiansen (1958) used chaetotaxy to a limited extent. He divided the body setae into five types based on shape and lengths, but made no use of gross body setal patterns except on the male genital plate. Yosii (1959) revised the genus §gi£§_and utilized the distribution of the macrochaetae on the tergites. Gisin (1960) used chaetotaxy of various groups to advantage in his discussion of species and included setal pattern drawings for his new species. As Yosii has pointed out in an earlier paper (1956), the use of chaetotaxy is an important taxonomic tool. Yosii (1960) refined his work on Hypogastrura and attempted to define the evolution of the selected species he worked with and to show affinities. Once again using chaetotaxy, Yosii (1961) surveyed Collembola, and related the family groups phylogenetically. Gisin (1961) in reworking the collection of Carl Borner elabo- rated species descriptions using chaetotaxy. Gisin and DaGama (1962) compared the chaetotaxy of three species of §gi£§. They found that the setae showed differences in relative distances from each other. As chaetotaxic technique developed, authors put it to use in difficult situations. Cassagnau (1964) made a comparative study of the dorsal chaetotaxy of Hypogastrura and was able to group closely allied species by pattern type. Massoud (1964) used a chaetotaxic table in describing a new species. Christiansen (1964) used position of the macrochaetae for specific identification. He also mentioned that the microsetae associated with the trichobothria are constant in position. Murphy (1966) discussed the taxonomy and bionomics of Sphaeridia utilizing the dorsal head and body chaetotaxy. He assigned a notation system to the setae which his descriptions of species followed. Betsch 3 and Cassagnau (1966) presented the evolution and form of the chaetotaxy of the abdominal papillae of Arrhopalites from the juvenile to the adult stage. Christiansen (1966) in a revision of Arrhopalites system- atically used chaetotaxy to characterize species. The understanding of the chaetotaxy for the genus Lepidocyrtus has been largely due to the efforts of one man, Dr. Hermann Gisin. In a paper dealing with the Lepidocyrtini, Gisin (1963) discussed the. pseudopores and chaetotaxy of this tribe, and illustrated the chaeto- taxic pattern for Pseudosinella, a genus closely allied to Lepidocyrtus. In this paper he outlined a basic chaetotaxic map analogous to the setal maps used in describing lepidopterous larvae, and set down a notation system for the tribe Lepidocyrtini. Gisin (1964a) presented a partial revision of the genus Lepidocyrtus s. str. in which he was able to show differences between species. This first article was concerned with seven species. Using only the mid-dorsal setae, he managed to develop four categorical chaetotaxic groups within the genus for European species: 1) Lepidocyrtus curvicollis Bourlet, Lepidocyrtus violaceous Geoffroy and Lepidocyrtus instratus Handschin; 2) Lepidocyrtus lanuginosus Gmelin and Lgpidocyrtus cyaneus Tullberg; 3) Lepidocyrtus paradoxus Uzel; 4) Lepidocyrtus fimetarius Gisin. Previously L. violaceous Geoffroy and L. cyaneus Tullberg had been difficult to separate. He noted that they could be distinguished with chaetotaxic characters. This discovery eventually led to other usable morphological differences in separating these two very similar species. Dr. Gisin showed that the dorsal chaetotaxy of abdominal segment IV differed between L. cyaneus and L. violaceous on the 4 microchaetal level. Gisin (1964b) later developed more refined tech- niques for their separation. His studies of the genus Lepidocyrtus led to the use of the taxonomic characteristics of fine structures associated with the macrochaetae which had heretofore never been considered. Gisin was able to separate L. lignorum Fabricius from L. curvicollis Bourlet, a Species that had up to this time masked lignorum on general morpho- logical characters. Gisin (1965) separated Lepidocyrtus pallidus Reuter from L. cyaneus Tullberg using chaetotaxy. At the same time he distinguished Lepidocyrtus serbicus Denis from L. pallidus Reuter and described a new species, Lepidocyrtus flexicollis Gisin, a species closely related to L. curvicollis. Hale (1966) made use of the precepts laid down by Gisin and studied L. lignorum intensively demonstrating that there is some varia- tion in macrochaetae size between individuals of the same species. Two of the species described as new in this paper were observed by Dr. Justus Watson Folsom in the late nineteen twenties. Dr. Folsom made preliminary observations of the species described herein, Lepidocyrtus millsi n. sp. and Lepidocyrtus floridensis n. sp., but never published his results. Through Dr. Harlow Mills the efforts of Dr. Folsom were made available. I have made use of Dr. Folsom's habit drawings where applicable and have given him credit. Death prevented the work on the genus Lepidocyrtus which Dr. Folsom has started. It is to his credit that work thirty years old has stood the test of time and is still valid. MATERIALS AND METHODS The specimens used in this study were obtained, where possible from the collections in the Entomology Museum, Michigan State Univer- sity. This collection was augmented by specimens of Lepidocyrtus on loan from: the Illinois Natural History Survey; the United States National Museum; the University of Michigan Museum; the collection of Dr. Kenneth Christiansen of Grinnell College, Iowa; the collection of Dr. H. Goto, Imperial College, London, England; and the Museum of Natural History, Geneva, Switzerland through Dr. Hermann Gisin. With- out the cooperation of these sources this study would not have been possible. All specimens which have been examined were taken from alcohol preserved collections for previously made slide mounts were not usually of the nature which allowed good microscopic work. In my experience, 95% ethanol is the best allaround preservative. It tends to make the specimens stiff, but the color and integrity of the exoskeleton re- main intact much better than in other preservative solutions which have been tried. To make observations of the chaetotaxy in the genus Lepidocyrtus, it was necessary that specimens be placed on microscope slides. Speci- mens of all species described in this paper were prepared in the fol- lowing manner: 1. The individuals were placed in 95% ethanol if not previously pre- served in the same. 6 They were decapitated and the appendages removed, including the collophore. The head was placed aside for separate mounting as it is easily lost in a watch glass of alcohol. With very fine pins mounted in match stick handles, a cut was made along the mid-ventral line from prothorax to anus. The Specimen was held by the furcula while the cutting was done. The preparation was then placed into a 5.25% solution of sodium hypochlorite. The clearing of the specimen must be closely ob- served since it praceeds very rapidly (3-5 minutes). Clearing in such a manner insures that all body contents are dissolved with nothing remaining except the exoskeleton. The cleared exoskeleton undergoes two rinses of distilled water which removes the sodium hypochlorite. The specimen was then placed on a microscope slide dorsal side up in a drop of water, and the slide was tilted at an angle so the water drained from beneath the specimen. Excess water was removed with blotting paper. A drop of CMC-10* was placed next to the wet preparation, allowed to penetrate the specimen, and a 12-mm number zero, round coverslip was placed on the slide. With the coverslip in place, generally heat from an alcohol lamp, would expand the exoskeleton and float folded edges into position. After 48 hours the coverslip could be ringed with asphalt. Specimens which were used for examination of the fine structures and trichobothria were mounted directly from 95% ethanol into CMC-lO * Available from Turtox, General Biological Supply House, Inc. and allowed to "cure" for at least a week. This process, although slow, retained the macrochaetae, trichobothria, and other fine structures in position. It is highly desirable to use this technique because it allows time to prepare a large quantity of slides in a short time. CHAETOTAXY I. The Macrochaetal Pattern The techniques referred to in the preceeding section permitted close examination of the dorsal and lateral macrochaetae. The basic positions of the dorsal macrochaetae and lasiotrichia proposed by Gisin (1964 and 1965) agree with the present work. However, he did not include the lateral setae placed the species he examined only into groups of species. I have attempted to follow his examples wherever possible, but have departed by showing a macrochaetal pattern for each species. The constituents of the macrochaetal pattern include the macro- chaetae, lasiotrichia, and pseudopores. The macrochaetae (fig. 1) are pubescent and arise from sockets surrounded by a chitinous ring. Lasiotrichia (Salmon, 1964) are long, fringed, sensory hairs (fig. 2) and are found on abdominal segments II, III, and IV. Pseudopores (Gisin and DaGama, 1962) are structures which resemble pseudocelli, but lack internal structure (fig. 3). Gisin and DaGama (1962) described a thin thread arising externally from the center of the pseudopore. I have not as yet observed such a structure. The pseudopores occur on each body segment and Gisin (1963) reports that they also occur on the coxae. Figure 4 is a composite chaetotaxy pattern and is representa- tive of all possible macrochaetae. A black dot indicates a macrochaeta, an open circle (0) represents a pseudopore, and a short, curved line 8 represents a lasiotrichium. The Species treated are arranged in order of their pattern com- plexity, beginning with the most complex. Three basic regions of the trunk are noted: the medial region (M), the paramedial (P), and the lateral region (L) (fig. 4). These regions are based on the natural groupings of the macrochaetae which are constant throughout the genus. All designated setae are indicated by a segment number, region letter, and position subscript number. For example, the first medial seta on abdominal segment IV is referred to as: ABD IV, Ml' Lasiotrichia are designated by a "t" and a subscript number such as: ABD IV, Mtz. By following this system, one is able to indicate the presence or absence of a given seta by a notation. Setae beyond the lateral line of the body are not indicated as they are beyond the scope of the present study, as are also the setae of the parafurcular lobes and the setae of abdominal segments V and VI. Abdominal segment IV is the most variable in number and position of setae. On the basis of macrochaetae, two distinct groups of species may be discerned; group ”A", with 3 medial macrochaetae; group "B", with two medial macrochaetae. If the species are arranged under A and B groups (table 1), they may be listed numerically from greater to lesser numbers of macrochaetae. 10 TABLE l.--Groups of species for North American Lepidocyrtus based on the numbers of medial macrochaetae of ABD IV "A" Group "B" Group L. lignorum L. cinereus unifasciatus lanuginosus finensis heleni curvicollis millsi neofasciatus floridensis paradoxus pallidus violaceous cyaneus Tables 2 and 3 summarize the macrochaetal pattern of the fourteen species examined. Thoracic segments II and III, and abdominal segment I only have pseudopores, otherwise completely lacking all chaetotatic elements, and are therefore omitted from tabulation. It is significant to note that M1 is always present on ABD II and always lacking on ABD III; likewise, the paramedials (P) are always lacking on both seg- ments. Lateral seta (L1) is consistently present on ABD II, but all other laterals are lacking on that particular segment. All fourteen species have the same pattern of lasiotrichia which is as follows: ABD II, Mt L 1, 1; ABD III, Mt Lt t 1, 1 2; ABD IV, Ptltz (fig. 4). Any unique positions or deletions are discussed under the individual species. 11 TABLE 2.--Lateral macrochaetotaxal formulae of abdominal segment III of Lepidocyrtus Species ,L. lignorum L1 L2 L3 unifasciatus L1 L2 L3 L4 finensis L1 L2 L3 curvicollis L1 L2 L3 neofasciatus L1 L2 L3 paradoxus L1 L2 L3 violaceous L1 L2 L3 cinereus L1 L2 L3 lanuginosus L1 L2 L3 heleni L1 L2 L3 millsi L1 L2 L3 floridensis L1 L2 pallidus L1 L2 L3 cyaneus L1 L2 12 oHA «HA NHA oq «AmANAHA ¢m Hm mzmz mummMNw oHA «HAMHANHAHHAOHA quANAHA ¢m Hm MZNE mmmwwflmm mag mHQqHAmHA qu mu mqqqmqmq mmqm MEN: mflmcmpwuofim qu NHAQHA dad mu ca qgmqmq mm mm Hm mZNz mewfla mHAwHANHAoHA «HA NHA mg 04 mANQHA ¢m Hm MEN: wmwflmm maqofiqmfiqqaq NHAHHQOHQ 0A «AmANA mmqm Hm mzwz mSwOCMNNGmH magnaqoaqmaqcaququA 0H4 wqmqoq d4 Na cm mmfim mzNz mmmmmmmm. naqoaqmfiqqaq HHAOHA mg mg «Amqmq mm mm Hm MENZHS msooomfiofl> wag OHA qHAmHA HHAOHAmAwq «Amqmqaq mm Hm MZNZHS mmmmmmmmm NHAQHQ «HA HHAOHA mg mg «gmANAHA mm mm Hm mZNZHZ msumfiommmomc mad NHAQHAmHAQHQ HHQOHA wqmqoq damqmqaq mm Hm MZNZHZ mfiHHoofi>uso wHAmHAoHA daumHA HHAOHA mg mg dumqmqaq mm mm Hm mZNzH: mmmmmmflw quNHAQHAmHAqHAmHANHAHHAOHAmA mqoq qA NAHA mm Hm MENZHZ msumwommmwcs NHAQHAmHQ¢HAmHANHAHHAoHA ma ogmqqqmqmgaq 0 mm mm Hm MENSHZ ammmmwflw. m. mwflomam mauHNwopfimmA mo >H ucmemm HmcHEopnm mo mmHDEuom meMuODmmzoouomZuu.m mqm maxopmumm WSHMHUmNWOQC meHooH>udo mHmCm:wm msumwommwwcs Enuocwfla 4| mofiomam mauumwdpflmoq mo HHH Qm< mo Ammqummmoomv mmummsoouofle MOM meDEuom m>HumpmmEoo Mo mHannu.q mqm