NOTES ON THE GENUS OREODYTES

Eleven species of Oreodytes have been collected by the author in the Pacific Northwest. Distributional data, by state and county, are presented for each species. Habitat and biological notes are also given. New state records are: 0. crassulus, Montana; 0. picturatus, Montana; 0. quadrimaculatus, Idaho and Montana. Additionally, significant range extensions within states are presented. Oreodytes species are relatively common inhabitants of cool and cold, higher elevation streams and small rivers that are common throughout much of the Pacific Northwest. The group was recently revised by Zimmerman (1985);. his study was slightly modified by Larson (1990). Little is known concerning the life histories of the 18 taxa. All, except for Oreodytes scitulus scitulus (LeConte), are restricted to the western United States and Canada. Specimens of Oreodytes species are most often found in flowing streams and small rivers, where they inhabit areas of emergent grasses along the shoreline, eddies with emergent grasses, and shoreline overhangs where vegetation, tree roots, and trapped debris provide refuges from strong current. This appears especially true for members of the angustior group of species (0. angustior (Hatch), 0. congruus (LeConte), 0. crassulus (Fall), 0. picturatus (Horn), 0. abbreviatus (Fall), 0. subrotundus (Fall), and 0. obesus cordillerensis Larson) which I encountered in my sampling. I collected very few scitulus group species (0. scitulus scitulus (LeConte), 0. snoqualmie (Hatch), and 0. alaskanus (Fall)) and, while they were found in the above habitats, they also occurred in areas of streams that lacked or had only slight flow. These latter habitats were often pools which had been cut off from the main stream as summer progressed. They were usually relatively shallow and developed luxuriant algal mats.