Genus Notomastus M. Sars, 1851

Type species: Notomastus latericeus Sars, 1851, by monotypy.

Diagnosis (after Magalhães & Blake, 2020). Prostomium conical, palpode present or absent; eyespots present or absent, when present as multiple spots. Peristomium clearly distinct from prostomium; achaetous segment absent. First chaetiger uniramous or biramous. Eleven thoracic chaetigers. Chaetigers 1–11 with only capillaries or last thoracic chaetiger transitional with notopodial capillaries and neuropodial hooks. Thorax clearly demarked from abdomen. Abdominal segments with only hooded hooks. Branchiae present or absent. Genital pores absent or present. Lateral organs present on thorax and abdomen. Pygidium without cirribut unknown for many species.