Two new species of Fluminicola (Caenogastropoda, Lithoglyphidae) from southwest Oregon, USA, and a range extension for F. multifarius

Abstract. We describe two new species of pebblesnails (Lithoglyphidae: Fluminicola) from southwest Oregon based on morphologic and mitochondrial DNA (COI, cytB) evidence. Fluminicola umpquaensis sp. n., which had been traditionally identified as F. virens prior to the recent restriction of the latter to the lower Columbia River drainage, lives in lotic habitats in the Umpqua River basin. This species is readily distinguished from closely related F. gustafsoni and F. virens by shell and anatomical characters, and by its mtDNA sequences (divergence >3.6% for both genes). Fluminicola fresti sp. n. ranges among lotic habitats in the North Umpqua River basin, and in the upper Rogue River drainage north of Little Butte Creek. This species differs from other congeners by >9.1% for both genes and is distinguished from closely similar and geographically proximal F. multifarius by several anatomical characters. Additionally, new records are provided for F. multifarius from the upper Rogue River basin south of Little Butte Creek, which extend the geographic range of this species about 80 km northward from the Sacramento River headwater region. This continues a recent series of taxonomic papers on the poorly known and little studied pebblesnail fauna of the vast Pacific watershed from northern California to southern British Columbia.