Euthelepus McIntosh 1885

Diagnosis by Hutchings et al. (2015: 251): ''Transverse prostomium attached to dorsal surface of upper lip; basal part usually with eyespots; distal part low, restricted to base of upper lip. Buccal tentacles all uniformly cylindrical. Peristomium forming lips, continuing dorsally as narrow annulation, with nuchal organs on anterior margin; short, hood-like upper lip, about as long as wide or wider than long; lower lip also short, button-like, restricted to oral area. Short anterior segments, usually visible all around body, segment 1 with ventral lobe marginal to mouth, segments 2–3 or 2–4 with lateral or ventro-lateral lobes. Three pairs of branchiae, beginning from segment 2, each pair with relatively few, thick and elongate branchial filaments progressively tapering to tips, mid-dorsal gap between filaments of each side within pairs absent or very narrow, at least on segment 2. Anterior body highly glandular ventrally, swollen, smooth to corrugated between neuropodia. Notopodia beginning from segment 3, extending for variable number of segments; distally bilobed notopodia, post-chaetal lobe sometimes longer, chaetae emerging between lobes. Winged notochaetae in anterior row, posterior row with winged or serrated notochaetae, sometimes changing types from anterior to posterior segments with notopodia. Neuropodia beginning from segments 4 or 5, as fleshy ridges anteriorly, as raised pinnules after termination of notopodia. Neurochaetae throughout as short-handled avicular uncini, with dorsal button at anterior third of base, short, conspicuous prow, and strongly curved, convex base; uncini in single, straight rows. Nephridial and genital papillae frequently absent. Pygidium unknown.''

Original diagnosis by McIntosh (1885: 443) "The new genus Euthelepus is intermediate between the Ampharetidae and the Terebellidae. The branchiae resembling those of the former, the hooks those of the latter."