Vol. 103, No. 4, September & October. 1992 135 EPHEMERELLA APOPSIS, A NEW SPECIES FROM ROCKY MOUNTAIN HIGH (EPHEMEROPTERA: EPHEMERELLIDAE) 1 * 2 W. P. McCafferty 3 ABSTRACT: A new species of mayflies, Ephemerella apopsis McCafferty, is described from male adults taken at 1 1,000 feet elevation in Colorado in 1947. The species is evidently closely related to the eastern species E. needhami McDunnough, both sharing deeply forked, spineless penes and a small body size. It is an apparent anomaly that larvae of the new species, which are predictably much different than larvae of other Ephemerella known from the mountain West have evidently not been recognized or reported by western stream biologists. During an intensive study of the Ephemeroptera fauna of Colorado, being conducted by myself and Boris C. Kondratieff and Richard S. Durfee of Colorado State University, a new species of the genus Ephemerella was discovered among pinned material housed in the Pur-due Entomological Research Collection (PERC). Several factors as-sociated with this new species make it noteworthy. First, this genus (both sensu stricto and sensu lato) is one of only a few groups of mayflies that are presently very well known in North America, especially in the wes-tern half of the continent, thanks to the revisionary work of R. K. Allen and G. F. Edmunds, Jr. in the 1960's (esp., Allen and Edmunds 1965). Second, male adults of the new species possess distinctive, deeply forked penes. Only in E. aurivillii (Bengtsson) in the West (two more species in the East) are males known to possess this type of genitalia, but this much larger species is different in all details from the new species and could not be confused with it. Third, the specimens of the new species were taken at 1 1,000 feet elevation at Chasm Lake in Colorado in 1947. These data, together with the fact that aquatic macrobenthic pop-ulations in Colorado have been sampled and studied intensively by many freshwater ecologists and biologists for many years, seem to sug-gest a couple of possible explanations for this new species being dis-covered only now. Apparently, it is either very rare and limited with respect to acceptable habitat (it may even be extinct), or its larvae the life stage of mayflies that has historically been most sampled in Colorado have been taken but misidentified as another species of Colorado Ephemerella. Other species of Ephemerella that have been 1 Received March 23, 1992. Accepted April 9, 1992. -Published as Purdue Experiment Station Journal No. 13367. 3 Department of Entomology, Purdue University, West Lafayette, IN 47907. ENT. NEWS 103(4): 135-138, September & October, 1992
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