Boccardia pseudonatrix Day, 1961 Fig. 7C

Larval morphology.

Slender and fusiform in overall body shape. Prostomium rounded with a slight anterior notch. Three pairs of eyes present, most median pair rounded and lateral pairs double-eyes. Body entirely faint yellow. Dorsal melanophore absent, slight black pigmentation present (Fig. 7C, left). Pygidium with dorsal gap, pigmented with yellow. Internally, the vestibule and pharynx brown or black, gut green in color. Gastrotrochs on chaetigers V and VII.

Remarks.

Adults of this species were non-boring and collected from mud deposits in crevices of shells of living C. gigas oysters in Tomiura. Adult morphology (see Abe et al. 2019b) agrees with the descriptions of B. pseudonatrix from South Africa (Day 1967; Simon et al. 2010) and Australia (Sato-Okoshi et al. 2008, as B. knoxi; see Walker 2013). The 18S rRNA gene sequences obtained in the present study completely match (1714/1714 bp) that of B. pseudonatrix from South Africa (KY677895) reported by Williams et al. (2017) (Fig. 3). Therefore, this species was referred to B. pseudonatrix .

Boccardia pseudonatrix has been reported to have adelphophagic larvae with a short or absent planktonic phase (Sato-Okoshi et al. 2008; Simon 2015). The larvae herein reported accidentally hatched from egg capsules in an adult tube during the process of extraction of the adult specimens.