Pararhynchelmis n. gen.

Included species: Pararhynchelmis murdocki n. sp.

Diagnosis. Small worms with rounded prostomium. Lateral blood vessels in middle and posterior segments unbranched. Preclitellar nephridia on 6/7. Pharynx without a distinct dorsal pad. Male pores in X, behind and slightly medial to chaetae; spermathecal pores inconspicuous, paired in VIII and IX, behind and slightly medial to chaetae; female pores on chaetal line, intersegmental on 11/12. Testes in IX and X, ovaries in XI. Spermathecae simple, roughly cylindrical; without ampulla or diverticula, connected to the gut entally. Atria petiolate, with thin duct, and club-shaped ampulla covered with multicellular prostate glands. Very short, retractable penes. Semiprosoporous; each atrium with two thin vasa deferentia; both anterior and posterior male funnels functional; posterior vasa deferentia do not form a loop in the postatrial segment or penetrate septum 10/11.

Etymology. From Latin para, “beside”, indicating its possible close relationship to Rhynchelmis.

Remarks. The single known Pararhynchelmis species, described herein, has male pores in X and spermathecal pores paired in both VIII and IX, distinguishing it from all other lumbriculids except for two Palearctic Rhynchelmis species (Rhynchelmis tetratheca Michaelsen and Rhynchelmis granuensis Hrabĕ). Four described genera (Rhynchelmis, Pseudorhynchelmis Hrabĕ, Secubelmis Fend & Gustafson 2001, and Tatriella Hrabĕ), plus two undescribed southeastern Nearctic species (S. Fend & D. Lenat, unpublished) have the first spermathecae located two segments anterior to the atria. Of these, only Rhynchelmis includes species in which the spermathecae connect to the gut (Martin & Kaygorodova 2008). Almost all described Rhynchelmis species have a long, filiform proboscis. The few species or subspecies without a proboscis (Rhynchelmis brachycephala brachycephala Michaelsen, Rhynchelmis komareki brevirostra Hrabĕ, and an undescribed Nearctic species [S. Fend, unpublished]) closely resemble proboscis-bearing species: they are all large worms, usually found in profundal lake habitats. The petiolate atria of Pararhynchelmis do not resemble those of any described Rhynchelmis species, and the very short, duct-like spermathecae are unique within the family. Other distinguishing characters are evaluated below, in the Discussion.

Pararhynchelmis has a narrower geographic range than any of the Rhynchelmis subgenera or species groups. The single known species has been collected only within a single spring system in the southern Appalachian Mountains, USA.