Lumbriculus genitosetosus

Lumbriculus genitosetosus was described by Holmquist in 1976 from almost 2,000 individuals collected in Northern Alaska.[1] Initially, Holmquist revived the genus Thinodrilus (previously established by Smith in 1895 for Th. inconstans) for L. genitosetosus, Lumbriculus inconstans and Lumbriculus ambiguus on the basis of the Lumbriculus-species having only one pair of vas deferens and sperm funnels per atrium, whereas the Thinodrilus-species have two (one in the anterior end and one in the posterior); this division is, however, not generally recognised today, even if Thinodrilus may be a valid subgenus.[2][3]

L. genitosetosus, as the name suggests, can be recognised by its modified male genital setae, unique within the Lumbriculidae.[4]