A new species of in the Rhyacophila vagrita group (Trichoptera: Rhyacophilidae) from Olympic National Park, Washington, USA.

Rhyacophila vagrita Milne, 1936 was described from specimens collected in British Columbia and Alberta, Canada. Ross (1950), while examining R. vagrita paratypes from Alberta, discovered four males that did not fi t the R. vagrita description. These he described and named R. milnei Ross, 1950. Ross (1956) established the R. vagrita group for R. vagrita and R. milnei based primarily on the synapomorphies of the “curious dorsal projections of both ninth and tenth tergites”, a very small simple aedeagus, and “a curious development of the apical band and anal sclerite”. Schmid (1970) indicated that males of the vagrita group have genitalia that are among the most unique in all of the species of Rhyacophila. While collecting in Olympic National Park, Washington, USA, we discovered an undescribed Rhyacophila species, most similar to R. milnei, with structures as remarkable as those described for R. vagrita and R. milnei