Prionospio krusadensis Fauvel, 1929 Fig. 5C, D

Larval morphology.

Long and thin in shape. Prostomium rounded anteriorly, lateral parts of the peristomium not especially well demarcated. Two pairs of red eyes arranged somewhat in trapezoidal shape, lateral pair kidney-shaped and situated anteriorly. Body extremely transparent (Fig. 5D). Green pigmentation on pharynx and pygidium (Fig. 5C, D). Caruncle develop in late larvae, extends posteriorly from posterior part of prostomium (Fig. 5C). In late larvae, branchial anlages occur from chaetiger II, pygidium acquires anal cirri.

Remarks.

Adult individuals of this species were collected from shallow subtidal muddy bottom sediments in Sasuhama in August 2011 by using a hand-scoop. The species was referred to P. krusadensis as the adult morphology agrees with the descriptions of this species by Imajima (1990a). The larvae and adults were confirmed to match (18S: 1749/1749, 16S: 506/507 bp) using molecular data (Fig. 2).

Planktonic larvae of this species were found in Sasuhama and Onagawa Bay in July and August, but they were rare in the plankton samples. Green pigmentation on the pharynx and pygidium is characteristic of the larvae of this species.