The Nearctic species of Rhynchelmis (Lumbriculidae) are distinguished frown the Palearctic group Rhynchelmis s. str. by longitudinal muscle bands that do not curl inwards. Six new species from western North America support the existence of two major groupings within the Nearctic fauna. Species in Group 1 are distinguished from other Rhvychelmis by large penial bulbs and multiple spermathecal diverticula. Within Group I, Rhynchelmis yakimorum n. sp., Rhynchelmis monsserratus n. sp., Rhynchelmis gustafsoni n. sp. and Rhynchelmis utahensis n. sp. differ from the related Rhynchelmis (=Sutroa) rostrata in having short penes and spermathecae with 2 short, lobed diverticula. R. monsserratus is distinguished by a single, median spermatheca, R. gustafsoni has closely appressed, median spermathecae and atria, and R. utahensis differs in structural details of spermathecae and male pores. Rhynchelmis gilensis n. sp. has a single, median spermatheca with unbranched diverticula and distinctive nephridia. Redescription of material from the type localities of both Sutroa alpestris and R. rostrata supports their combination. Group 2, corresponding in part to Rhynchelmoides, is distinguished from Group 1 mostly by characters that are inconsistent or appear plesiomorphic. Within Group 2, Rhynchelmis saxosa n. sp. closely resembles Rhynchehlmis alaskana, except for the absence of lateral blood vessels in posterior segments and distribution of prostates. Rhynchelmis elrodi and Rhynchelmis glandula consistently differ in presence of ventral glands and have different distributions, so their supposed synonymy is rejected.
Additional publication details
New species of Rhynchelmis (Clitellata, Lumbriculidae), with observations on the Nearctic species