Genus Heteromastus Eisig, 1887

Type species: Capitella filiformis Claparède, 1864

Diagnosis (after Green 2002). Prostomium short to long, conical, sometimes tapering, eyes present or absent. Thorax with 12 segments including an achaetous peristomium and 11 chaetigers. Chaetiger 1 biramous. Chaetigers 1–5 with capillary chaetae, chaetigers 6–11 with long-shafted hooded hooks. Abdominal chaetigers with short–shafted hooded hooks. Branchiae may be present on posterior abdomen.