Polaruschakov Pettibone, 1976: 55. – Uschakov, 1982: 124 (translated version). – Jirkov, 2001: 133. – Barnich & Fiege, 2003: 92.
Type species: Macellicephala polaris Uschakov, 1957.
Diagnosis (emended): Short body, dorsoventrally flattened, up to 25 segments. Frontal filaments absent. Eyesabsent.Medianandlateralantennaeabsent.Facial tubercle absent. Reduced palpophores. Tentacular segment fused with prostomium, tentaculophores without acicula or chaetae. Pharynx with seven pairs of distal papillae; two pairs of jaws with smooth margins or with a secondary small tooth (Polaruschakov lamellae sp. nov. and Polaruschakov omnesae sp. nov.). Dorsal tubercles present (Polaruschakov lamellae sp. nov. and Polaruschakov polaris) or absent (Polaruschakov reyssi, Polaruschakov limaae sp. nov. and Polaruschakov omnesae sp. nov.). Elytrophores prominent, up to ten pairs, on segments 2, 4, 5, 7, 9, 11, 13, 15, 17 and 19. Parapodia subbiramous, notopodia shorter than neuropodia; noto- and neuropodia with elongate acicular lobe; tips of noto- and neuroaciculae not penetrating epidermis. Notochaetae distally with spinous rows; notochaetae more slender than neurochaetae. Neurochaetae numerous, serrated along both margins. From segment 3, ventral cirri inserted medially on neuropodia. Nephridial papillae small. Pygidium small, with terminal anus.
Remarks: The diagnosis of genus Polaruschakov is emended to include the following characters observed in the new species described below: jaws with small secondary tooth on margin and absence of flattened scale-like structures on segment 6. As highlighted for Hodor gen. nov., this feature, occasionally present on anterior segments, is likely to be a reproductive character, as suggested by its presence or absence without pattern among the taxa belonging to the Anantennata clade (i.e. without median and lateral antennae).