Transactions of the American Entomological Society 127(1): 5-29, 2001 Mayflies (Ephemeroptera) of the Great Plains. I: Nebraska W. P. McCafferty Department of Entomology, Purdue University, West Lafayette, IN 47907 Tom H. Klubertanz - Department of Biological Sciences, University of Wisconsin Rock County, Janesville, WI53546 R. P. Randolph Department of Entomology, Purdue University, West Lafayette, IN 47907 Arwin V. Provonsha Department of Entomology, Purdue University, West Lafayette, IN 47907 H. R. Lawson Division of Science and Mathematics, Chadron State College, Chadron, NE 69337 B. C. Kondratieff Department of Bioagricultural Sciences and Pest Management, Colorado State Univ., Fort Collins, CO 80523 abstract A 39 are total of 13 families, genera, and 81 species of Ephemeroptera state reported from the of Nebraska, including the first published state records two are new for families, 13 genera, and 38 species. Also provided 335 county are now records for 65 of the species. Mayflies known from 60 of the 93 areas Nebraska counties and from all drainage represented in the state. Most are common species of the Nebraska fauna relatively in North America. Notable exceptions include Apobaetis lakota McCafferty, Brachycercus edmundsi B. nasutus Sold?n, Sold?n, Cercobrachys serpentis Sold?n, Leptophlebiagravastella and (Eaton), Paraleptophlebia gregalis (Eaton). Much of the mayfly fauna is are psammophilous, being typical of sand-bottomed streams, which predomi nate throughout much of the state. The generally mixed North American of are geographic affinities the Nebraska fauna tabulated, and several species significantly demonstrate their eastern, western, or northern range limits in this north-central plains state. 6 GREAT PLAINS MAYFLIES BACKGROUND AND DISCUSSION Nebraska was one of several North American states indicated by McCafferty (2000a) as not having been studied to any significant extent with to its fauna. respect Ephemeroptera Study of the Nebraska mayflies was deemed because the central important of geographic position of the its state, relatively large size (77,227 square miles), and its extensive sand bottomed streams and rivers. the Nebraska fauna Thus, could yield data for important understanding transcontinental ranges of the North as a American fauna well providing better understanding of the poorly known psammophilous mayfly fauna (e.g., see McCafferty 1991). Ratcliffe (1990) provided an excellent physiographic review of this state from the perspective of insect habitat. Nebraska is primarily prairie with six different short and tall grassland types found throughout most of the state, although much of the prairie is now in cultivation. Pine ridges to the extent of elevation occur in the far western 5,340' portion of the state, and deciduous forest as low as 835' elevation may be found in the in Missouri Valley the extreme southeast. In the western two-thirds of the state are the Nebraska Sand Hills (19,300 square miles), the largest sand dune area in the Western Hemisphere. Streams range from low flow with moderate and mixed springs gradient substrates (e.g., Chadron Creek) to moderately large streams with predominately silt and sand bottoms Elkhorn to low (e.g., River) long, meandering, gradient streams, often ribboned due to considerable draw down for agricultural and seasonal low precipitation, that typically exhibit clean shifting sand substrates Niobrara to (e.g., River) the large Missouri River. Previous to this study, published reports of mayflies from Nebraska with associated record data included only 28 species (Traver 1935, Spieth 1941, Hamilton 1959, Swanson 1967, McCafferty 1975, Bednarik and McCafferty 1979, Kondratieff and Voshell 1984, Moul 1984, Pescador 1985, Provonsha and McCafferty 1985, McCafferty and Waltz 1986, Darrow and Pruess 1989, Provonsha 1990, Harris et al. 1999, Klubertanz and Jones 1999, McCafferty 2000b, Wiersema and McCafferty 2000). Five unpublished theses (Hamilton 1952, Pesek 1974, Carnevalo 1981, Decker 1981, Angle 1987) provided data associated with mayflies in Nebraska. Any reports of species in Nebraska contained in those studies are noted in the present study with respect to those that could be verified with additional records given herein or elsewhere or those that should have been identified with confidence at the time considering the state of taxonomic and available aids. knowledge diagnostic Voucher materials from the Carnevalo and Decker theses, if existent, were not made avail to us able upon request; however, AVP verified several of the species involved at the time of the studies. Several vouchers from the Hamilton that (1952) study had been initially deposited at the University of Utah now at were and reside PERC examined by WPM. Eleven of the 81 species herein remain based on or reported entirely unpublished theses abstracts thereof (Carnevalo and Lunt 1982, Decker and Lunt 1982). Our review of previous reports and study of large collections of Nebraska accumulated us Ephemeroptera variously by for the past W. P. MCCAFFERTY ET AL. 7 have occurrence of 13 39 nearly 25 years, indicated the families, genera, in the state. Reviewed and new data are and 81 mayfly species presented 1 is as a indication of the in the text, and Table provided summary geographic affinities of the Nebraska species. From Table 1, it can be seen or less com that several species find their western, eastern, northern, monly southern distribution limits in Nebraska, and that Nebraska is a area with to the eastern and western North clearly transitional respect American fauna. Of considerable interest is the fact that certain otherwise southwestern species have been found in the Pine Ridge area of far and western Nebraska, for example, Baetis magnus McCafferty and Waltz western Caenis bajaensis Allen and Murvosh. Some widespread species, as are also common Ne such Heptagenia elegantula (Eaton) throughout braska but remain unknown east of there. Several eastern and mid western western limits in eastern for species apparently find Nebraska, example, Tricorythodes allectus (Needham) and Stenonemafemoratum (Say), although some of these, such as the latter, occur somewhat farther west in Canada (McCafferty and Randolph 1998). Nebraska serves as a bridge between western eastern for certain such as and populations species Ephemerella inermis Eaton and Stenonema terminatum (Walsh). None of the 81 mayfly are to species endemic Nebraska. vast are common The majority of Nebraska mayflies species through out in America. In their ranges North particular, however, Nebraska has a relatively rich fauna of caenid mayflies (both Caeninae and Homoeoneuria Brachycercinae), long-clawed Baetidae, Pseudironidae, and - (Oligoneuriidae) all groupings commonly associated with sand sub strates. Generally poorly known and infrequently taken mayflies found in Nebraska include Apobaetis lakota McCafferty, Camelohaetidius waltzi B. nasutus B. McCafferty, Brachycercus edmundsi Sold?n, Sold?n, prudens (McDunnough), Caenis youngi Roemhild, Cercobrachys serpentis Sold?n, Homoeoneuria ammophila (Spieth), Leptophlebia gravastella (Eaton), and Paraleptophlebia gregalis (Eaton). The first two species have only recently been discovered, are small and difficult to collect, and thus it is premature to estimate or environmental status. their potential rarity Species of are Brachycercus and Cercobrachys poorly understood, and thus many are not to no collected specimens identified species, and valid estimation or concern can of rarity environmental be made for these species at this time. In addition, the sand-silt habitats that Brachycercinae are found in are often not sampled adequately. Recent collections of C. youngi by WPM and AVP outside Nebraska would indicate that this species ismuch more common than Homoeoneuria is more previously thought. probably common than reports would indicate because its psammophilous habitat not taxonomic status has been adequately sampled. The of L. gravastella must be validated before estimates of rarity are assigned to it. Also, future studies of western species of the genus Paraleptophlebia should reveal the true commonness of P. a that not gregalis, species notably had been as far east as previously reported Nebraska. Historical and new faunistic data are reported below with no further comment. Presentation is alphabetical by family, genus, and species. All 8 GREAT PLAINS MAYFLIES or not and whether or previous reports, whether published complete not, are Previous New state and records are given under reports. county in the first name of collectors are record given full. Only any given per in case If a (abbreviated the of present authors). species has previously for a additional records from that are not been reported county, county names in all letters for easier given here. County appear capital tracking. counties with stream are For reference, the location of along key systems on state in 1. Data are shown the Nebraska map given Fig. abbreviated as as to conserve The materials for which much possible printed space. new data are are in the Purdue Entomo record reported mostly deposited material logical Research Collection (West Lafayette, Indiana). However, associated with collectors names including Klubertanz (THK), Clopton, or Sorgenfrei are deposited in the private collection of THK (Janseville, new state are Wisconsin), except for material contributing records, which also deposited in PERC. Those with collectors name including Kondratieff (BCK), Harris, or Opler are deposited at the C. P.