Pilaridrilus, Fend, Steven V. & Lenat, David R., 2007

Fend, Steven V. & Lenat, David R., 2007, Two new genera of Lumbriculidae (Annelida, Clitellata) from North Carolina, USA, Zootaxa 1666, pp. 1-22 : 3

Pilaridrilus n. gen.

Diagnosis. Medium-sized to large worms with rounded-conical prostomium. Chaetae simple-pointed, sigmoid. One pair of lateral, branched, blind blood vessels present in posterior segments. Holandric, testes usually in IX and X; one pair of ovaries, usually in XI. Male pores usually in X, near 10/11, paired on chaetal lines. Penial structures complex, with a thick-walled chamber and a very long, thin, retractable penis. Atria petiolate, ental 3/4 or more loosely covered with multicellular prostate glands. Atrial musculature in orthogonal layers; the inner transverse, the outer longitudinal. Two pairs of male funnels; the anterior may be smaller than the posterior. Vasa deferentia do not penetrate posterior septum (10/11); they join atria near the ental end; both vasa with a thin muscle layer in ectal part. One pair of spermathecae; pores somewhat lateral to ventral chaetal lines, five segments behind male pores (usually in XV). Spermathecae complex: a narrow, ectal vestibule is followed by a thin duct leading to the ampulla; ectal chamber of ampulla narrow, with epithelium forming many lamellae, separated from the wide ental chamber, which has thin epithelium. Entire sequence of reproductive organs may be shifted forward by two segments.

Remarks. Pilaridrilus can be separated from all other Lumbriculidae by the position of the spermathecal pores, which are five segments behind the male pores or four segments behind the ovaries. In other genera having post-atrial spermathecae, the first pair are usually in either the first or second post-atrial segment. Exceptions include a few hologynous species (some Lumbriculus ambiguus [Holmquist] and Lamprortus orientalis Rodriguez ), and the genus Styloscolex Michaelsen (which has ovaries in the second post-atrial segment); in those cases, the first spermathecae are in the first post-ovarian segment. Morphology of the spermathecae and the male pores is also unique, although there are some similarities with both Lumbriculus and Eclipidrilus (Premnodrilus) ; those characters will be discussed below. Pilaridrilus is currently monotypic; the single species, Pilaridrilus uliginosus , is known from a single site in North Carolina, southeastern USA.