Contributions towards a review of the genus Rhynchelmis Hoffmeister (Clitellata: Lumbriculidae)
Morphological characters for several Palearctic taxa attributed by recent authors to the genus Rhynchelmis Hoffmeister, 1843 were reviewed using new or previously studied museum specimens. The genus Rhynchelmis s. lat. was supported, and the Palearctic subgenus Rhynchelmis (Rhynchelmis) was proposed, based on several probable synapomorphies: longitudinal muscles with lateral margins curled; strong dorsolateral-transverse muscles; vasa deferentia with thickened, glandular epithelium; spermathecal ampullae with anterior, sacciform diverticulum; accessory organ often present in preatrial segment. The Japanese Rhynchelmis orientalis Yamaguchi, 1936 was redescribed using new material, and had none of the abovementioned characters. The separation of other potential subgenera, the Rhynchelmoides and Sutroa groups, is still subject to review of those primarily Nearctic taxa. Attribution by Kaygorodova & Liventseva (2007) of several Lake Baikal species to Pseudorhynchelmis Hrabě (1982) was supported, and Rhynchelmis paraolchonensis Giani & Martinez-Ansemil, 1984 may also belong in Pseudorhynchelmis.