On the genus Eclipidrilus Eisen, 1881 (Lumbriculidae, Clitellata), including a description of Eclipidrilus ithys sp.nov.

The genus Eclipidrilus is recognized from the unique apomorphy of elongate atria with spiral muscles. The spermathecae are in segment IX, the male pores in X, and female pores in 10/11; testes are found in IX-X or X and ovaries in XI. The seven North American species, one of which has been recorded from Wales, differ in regard to the presence or absence of a proboscis, the median unpaired or lateral paired gonopores, the form of the penes, and the number of spermathecae and (or) atria. The primary characteristics of Eclipidrilus ithys sp.nov, are that it lacks a proboscis, it has a small penis, and while there may be one or two atria, the atrial pores are ventrolateral (not median), the ejaculatory duct forms an upright structure in X, and the spermathecal and male pores are not enclosed in massive glands.