Genus Prionospio Malmgren, 1867

Larval diagnosis.

Overall shape long and slender. Prostomium rounded anteriorly. Lateral parts of peristomium not demarcated from the prostomium. Two pairs of red or dark red eyes present. Pigmentation usually absent except for eyes and on pygidium. Some species (e.g., P. steenstrupi and P. krusadensis) have red or green pigmentation on pharynx, dorsal side, and/or pygidium. Nototrochs absent or occur in branchial chaetigers in late larvae. Gastrotrochs occur in all chaetigers from chaetiger II-IV onwards (Thorson 1946, as Disoma; Hannerz 1956; Plate and Husemann 1994; Radashevsky et al. 2006).