The Caddisflies(Insecta: Trichoffera)Of the Lake Itasca Region, Minnesota, and a Preliminary Assessment of the Conservation Status of Minnesota Trichoptera
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THE CADDISFLIES(INSECTA: TRICHOFFERA)OF THE LAKE ITASCA REGION, MINNESOTA, AND A PRELIMINARY ASSESSMENT OF THE CONSERVATION STATUS OF MINNESOTA TRICHOPTERA A THESIS SUBMMTD TO THE FACULTY OF THE GRADUATE SCHOOL OF THE UNIVERSITY OF MINNESOTA BY MARGOT PECK MONSON IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE SEPTEMBER, 1994 .2:-?, FISHERIES, I WELLAAVE LIBRARY p El 6 if 9? JAN12 3 T 0 Margot Peck Monson 1994 ACKNOWLEDGMENTS I would like to express my sincere gratitude to my major advisor, Dr. Ralph Holzenthal, for taking me on as his student and for his time, effort, and patient guidance in helping me pursue this project. I also wish to thank Dr. Roger Moon for his helpful counsel and encouragement, as well as the other members of my examination committee, Dr. William Miller and Dr. Francesca Cuthbert, for their support. I am grateful to Dr. 0. J. Flint, Dr. Steve Harris, Dr. David Etnier, and the Illinois Natural History Survey for their assistance in making specimens available and for verification of some determinations. Dr. Etnier was also most generous in making several donations to the University of Minnesota Insect Collection. I am thankful for the partial funding for this project, contributed by the Nongame Wildlife Program of the Minnesota Department of Natural Resources and the Minnesota Chapter of The Nature Conservancy. The helpfulness of Dr. Phil Clausen, Curator of the University of Minnesota Insect Collection, was most appreciated (as was his willingness to answer my many questions). The friendship and good humor extended by my colleagues in the lab, Roger, Atilano, Jolanda, Sonia, John, and Marc, as well as Sue, Paul, Sujaya, and Diann will be fondly remembered. My friends Dave, Linda, Bill and Martha, were helpful from the first days of my study and the support of Ann and Ginner in the field was invaluable. Without the love and constant encouragement from my husband, Bjorn, and children, Amy and Bjorn, I would not have been able to complete this project. To them I will always be deeply grateful. 1 TABLE OF CONTENTS ACKNOWLEDGMENTS TABLE OF CONTENTS LIST OF TABLES iv LIST OF FIGURES ABSTRACT 1 PART I INTRODUCTION 3 Trichoptera 7 Morphology 7 Biology 8 Case and Retreat-making Behavior 9 Trophic Relations 13 Distribution 16 MATERIALS AND METHODS 17 Study Area 17 Collection Sites 17 Collection Techniques and Equipment 20 Species Determinations and Depositions 24 Diversity and Similarity Indices 26 •• II RESULTS 28 Annotated Species List . 28 Species Richness and Relative Abundance 63 Seasonal Distribution 77 DISCUSSION 87 SUMMARY AND CONCLUSIONS 98 LITERATURE CITED 100 PART II A NEW SPECIES AND NEW RECORDS OF OXYETHIRA (TRICHOPTERA: HYDROPTILIDAE)FROM MINNESOTA 112 ABSTRACT 113 INTRODUCTION 113 METHODS • 113 DISCUSSION 116 ACKNOWLEDGEMENTS 117 LITERATURE CITED 117 PART III A PRELIMINARY ASSESSMENT OF THE CONSERVATION STATUS OF MINNESOTA TRICHOPTERA 119 LITERATURE CITED 135 111 LIST OF TABLES PART I Table 1. All caddisfly species and their abundances in collections from four sites in Minnesota during 1988 and 1989 29 Table 2. Species richness, diversity, and evenness 64 Table 3. The 15 most abundant species collected at each site 70 Table 4. Ratios of females to males for those species most abundant and collecteed in 1988 and 1989 at each creek site, and from Beaver Lake 75 Table 5. Similarity of caddisfly fauna between sites based on Sorensen's coefficient of similarity. 76 Table 6. Seasonal distribution of caddisfly species collected from the Itasca region of Minnesota, 1988 & 1989 78 Table 7. A comparison of caddisfly species richness at regional and local scales 88 PART III Table 1. Annotated checklist of the Trichoptera of Minnesota 123 iv LIST OF FIGURES PART I Fig. 1. Phylogeny of the Trichoptera. 11 Fig. 2. Collection sites for Trichoptera in the Lake Itasca region in northern Minnesota. 18 Fig. 3. Collection sites. A. Nicollet Creek; B. Beaver Lake 19 Fig. 4. Collection sites. A. Sucker Creek; B. LaSalle Creek 21 Fig. 5. A. Light trap; B. Malaise trap 23 Fig. 6. Rank abundance for the 25 most common species from all sites, 1988-1989. 65 Fig. 7. Rank abundance for the most common species at Nicollet Creek, 1988-1989. 66 Fig. 8. Rank abundance for the most common species at LaSalle Creek, 1988-1989 67 Fig. 9. Rank abundance for the most common species at Sucker Creek, 1988-1989 68 Fig. 10. Rank abundance for the most common species at Beaver Lake, 1989 69 Fig. 11. A comparison of rank abundance at Nicollet Creek, 1988 and 1989 71 Fig. 12. A comparison of rank abundance at LaSalle Creek, 1988 and 1989 72 Fig. 13. A comparison of rank abundance at Sucker Creek, 1988 and 1989 73 Fig. 14. Phenology of the most common species at Nicollet Creek, 1988 and 1989 83 Fig. 15. Phenology of the most common species at LaSalle Creek, 1988 and 1989 84 Fig. 16. Phenology of the most common species at Sucker Creek, 1988 and 1989. 85 Fig. 17. Phenology of the most common species at Beaver Lake, 1989 86 PART II Fig. 1. The three major biomes of Minnesota and the distribution of 0.itascae, n. sp. Inset: Approximate extent of the same biomes in the Great Lakes region 114 Fig. 2. Oxyethiraitascae, new species, male genitalia. A. Segments VII-X, lateral; B. Segment IX, lateral; C. Segment VIII, dorsal; D. Segments VIII and IX, ventral, inset: details of inferior appendages, subgenital processes, and bibbed processes; E. Phallus, dorsal. Abbvreviations: bp = bibbed process; ia = inferior appendage; sg = subgenital process; sl = setal lobe 115 vi ABSTRACT Objectives of this survey and subsequent study were to prepare an annotated species list of the caddisflies from the Lake Itasca region, to record relative abundance and seasonal distribution for these species, and to compare the diversity and similarity among the caddisfly communities at each site. A companion study was initiated to make a preliminary assessment of the conservation status of all Trichoptera species known from Minnesota at this time. Annotated records are presented for 126 species of caddisflies representing 37 genera in 13 families. Records are based on 73 light trap collections of over 95,000 adult caddisflies from four sites in the Lake Itasca region of northern Minnesota: LaSalle Creek, Nicollet Creek, Sucker Creek, and Beaver Lake. Caddisflies were collected from June- October 1988, and May-October, 1989. Rank abundance graphs are used to present relative abundance data for the most common species; among these, Cheumatopsyche pettiti, C. oxa, Hydropsyche tnorosa, H. slossonae (Hydropsychidae), Leptocerus americanus, Ceraclea alagma, C. cancellata, C. excisa, Oecetis inconspicua, 0. avara, 0. cinerascens, Triaenodes marginatus, T. tardus(Leptoceridae), Lepidostoma bryanti (Lepidostomatidae), and Pycnopsyche glint:ter(Limnephiliciae), include the five most abundant species from each site. The families Leptoceridae and Hydropsychidae represent 90% of the total individuals reported. Differences in species richness, relative abundance, and sex ratios are discussed for each site each year. There were generally more species and individuals collected in 1989 than 1988, and among the most common species, females frequently outnumbered males. The Brillouin and Shannon indices and an evenness formula were used to determine that all sites have moderate species diversity. Sorensen's index of similarity is employed to describe beta diversity; based on quantitative information, the degree of similarity is high for Nicollet Creek, Sucker Creek, and Beaver Lake. Seasonal distribution is recorded for all species for 1988 and 1989. The first flight activity is reported near the end of May for several Cheumatosyche and Hydropsyche (Hydropsychidae) and Oxyethira (Hydroptilidae) species, and for Limnephilus parvulus and Nemotaulius hostilis (Limnephilidae). The last flight activity- of the year is recorded during the second week of October for P. guttifer and Neophylax concinnus (Uenoidae). Considering all sites collectively, species found to be most common over the two-year period were generally active over the entire season,from late spring to mid-autumn; C. pettiti, O. incompicua, 0. avara, T. marginatus, and H. morosa are among these species. 1 In comparison, certain species were encountered only for limited periods, such as Fabria inornata (Phryganeidae) and Hesperophylax designatus(Limnephilidae), collected only in June, and Glossosoma intermedium and Protoptilatenebrosa (Glossosomatidae), found only from late July through mid-August. A new species, Oxyethiraitascae Monson and Holzenthal, was discovered at Nicollet Creek during the study; in addition, Oxyethiraverna, Hydroptila wyomia, H. xera, Polycentropus clinei, P. iculus, Pycnospyche limbata, Ceracleavertreesi, Oecetisnocturna, and Triaenodes ignitis, collected during this study, are new records for Minnesota, and 0. ecornuta is a new record for Minnesota and the United States. Other new State records were encountered during examination of museum specimens and include Hydroptila angusta, Hydroptila antennopedia, Diplectronatnodesta, Oligostomisocelligera, Micrasema gelidum, ironoquialyrata, Onocosmoecus quadrinotatus, Pycnopsyche aglona, Goera stylata, Lepidostoma sackeni, and Ylodesfrontalis. The conservation status of Minnesota Trichoptera is discussed and species are classified as endemic, disjunct, regionally restricted, range limited, or widely distributed. Recommendations are made for future study of the endemic, disjunct, and regionally restricted species. Endemic species are