Cenogenus Chamberlin, 1919, emended Carrera-Parra, 2001

Type species. Cenogenus descendens Chamberlin, 1919

Diagnosis. Prostomium with one antenna, without eyes; notopodia slightly developed; branchiae associated to anterior parapodia; simple multidentate hooded hooks present; pygidium with anal cirri; maxillary apparatus with four pairs of maxillae, carriers as long as MI, joined to entire base of MI; MI forceps-like without internal accessory teeth, with attachment lamella; MII as long as MI, with ligament, attachment lamella wide along 1/2 of posterior lateral edge; without connecting plates; MIII completely pigmented, attachment lamella wide along entire lateral edge; MIV completely pigmented, attachment lamella wide. Mandible fused up to 3/4 of its length.