Thelepus Leuckart, 1849

Thelepus Leuckart 1849: 169; Hutchings 1997a: 145.

Type species. Amphitrite cincinnatus Fabricius, 1780, by monotypy.

Diagnosis. Tentacular membrane short, compact, collar-like, usually with numerous eyespots. Branchiae as numerous simple filaments arranged in transverse rows typically on segments 2–4, sometimes only on segment 2, and occasionally absent. Notopodia from segment 3, continuing for numerous segments. Notochaetae smooth- tipped, narrowwinged capillaries. Neuropodia from segment 5, continuing for numerous segments, uncini arranged in one single row, avicular, with prow below dorsal button, variously developed.

Remarks. While over 40 species of Thelepus have been described, data on many of the characters critical for species determination are lacking for many species. These missing data include relative numbers and length of branchial filaments, their arrangement, any lateral extension of filaments, presence or absence of medial gap between branchial pairs, dental formulae of uncini, shape of uncini or the range of uncinial variation within a row and along the body, and the average number of pairs of notopodia relative to the total number of segments. A revision of the genus is needed, including a redescription of the type species Thelepus cincinnatus (Fabricius, 1780) .