New Nearctic Eremidrilus species (Clitellata: Lumbriculidae). Part 2, western species with one spermathecal segment

Three new species of the lumbriculid genus Eremidrilus Fend Rodriguez, 2003 are described from rivers in California, Nevada and Idaho, USA. The new species share the typical characters of the genus: a filiform proboscis, semiprosoporous male ducts and atria in X, spermathecae paired in the postatrial segment and male pores usually associated with distinct porophores. Species in Eremidrilus have either two spermathecal segments, XI and XII, or only one, XI. Compared with other Eremidrilus species having only one pair of spermathecae in XI, E. chalonensis n. sp. is mainly distinguished by the presence of a ring of glands at the spermathecal pore; E. pinedai n. sp. has a very small atrium and porophore; E. owyhee n. sp. has a thin, cylindrical atrium and a very long porophore. The spermathecal pores open in line with ventral chaetae in E. chalonensis, a position which separates it from previously described California species where the pore opens in a more lateral position. In contrast, the spermathecal pores in E. owyhee open at the lateral line in a transverse body fold. Most Eremidrilus species described so far show narrow endemicity, and their geographic distributions are restricted to small hydrographic areas. Only E. felini and E. owyhee have distribution ranges greater than 200 km. We provide a key to all known species of Eremidrilus.