Pararhynchelmis, Fend, Steven V. & Lenat, David R., 2010

Fend, Steven V. & Lenat, David R., 2010, New southeastern Nearctic Rhynchelmis (Rhynchelmoides) species and the description of Pararhynchelmis n. gen. (Annelida: Clitellata: Lumbriculidae), Zootaxa 2554, pp. 1-22 : 14

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Fend & Gustafson 2001 , and Tatriella Hrabĕ ), plus two undescribed southeastern Nearctic species (S. Fend & D. Lenat, unpublished) have the first spermathecae located two segments anterior to the atria.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brachycephala Michaelsen , Rhynchelmis komareki brevirostra Hrabĕ , and an undescribed Nearctic species [S. Fend, unpublished]) closely resemble proboscis-bearing species: they are all large worms, usually found in profundal lake habitats.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.