Genus Spio Fabricius, 1785

Spio Fabricius, 1785; type-species: Nereis filicornis Müller, 1776 .

Paraspio Czerniavsky, 1881; type-species: Spio decoratus Bobretzky, 1870, by monotypy. Euspio McIntosh, 1915; type-species: Euspio mesnili McIntosh, 1915 .

Diagnosis. (Bick & Meißner 2011, amended) Prostomium anteriorly rounded, truncate or slightly incised, lacking frontal or lateral horns; eyes present or absent; digitiform occipital antenna absent, but posterior portion of prostomium may be raised or inflated. Nuchal organ with short median and long lateral ciliary bands, extending to chaetiger 2 or 3. Metameric dorsal ciliated organs present. Branchiae present from chaetiger 1, continuing almost throughout the body, completely separate from or basally fused with notopodial lamella, often reduced in size on chaetiger 1. Ventral epidermal glands usually present in anterior and middle chaetigers. Notochaetae and anterior neurochaetae all capillaries; capillaries, hooded hooks and inferior sabre chaetae on middle and posterior chaetigers. Pygidium with four anal cirri.