A NEW SPECIES OF SPRINGSNAIL (PYRGULOPSIS) FROM THE OWYHEE RIVER BASIN, NEVADA

摘要

We describe a new springsnail species, Pyrgulopsis cybele, from the Owyhee River basin (northwestern Nevada) based on morphologic and molecular (mtCOI) evidence. Pyrgulopsis cybele differs from other members of its genus in its unique pattern of penial ornament, which consists of small glands on the distal edge of the penial lobe, base of the penial filament, and outer edge of the medial section of the penis. It is further differentiated from regional congeners by its thickened inner-shell lip and mtCOI sequences. A Bayesian analysis based on COI data placed P cybele in a well-supported clade that contained congeners from Snake River, Great Basin, Colorado River, and California Pacific Coastal drainages; the sister taxon of this new species was not resolved. The COI divergence of P cybele relative to its most genetically similar congener (P glandulosa) suggests that it evolved subsequent to emplacement of the Miocene basalt that carpets the upper South Fork Owyhee basin. Pyrgulopsis cybele was collected from 2 closely proximal springs along the South Fork Owyhee River below the Nevada Pipeline Crossing. Although these populations are in a remote wilderness study area, they may be threatened by livestock grazing and human disturbance.