Boccardia sp. 1 Fig. 7D-F

Larval morphology.

Slender and slightly fusiform in overall shape, widest in anterior part of body. Prostomium rounded anteriorly. Three pairs of black eyes present, most median pair rounded and lateral pairs double-eyes. Body entirely yellowish in color. A prominent row of dorsal melanophores occurs medially from chaetiger IV, lateral black pigment spots present from chaetiger V onwards (Fig. 7E). Pygidium with dorsal gap, pigmented with black color. Vestibule black, gut orange in color internally. Larval chaetae on first chaetiger long especially in early larvae (Fig. 7D). Gastrotrochs on chaetigers III, V, VII, X, and XIII.

Remarks.

No adult individuals of this species were collected in the present study. The 18S and 16S rRNA gene sequences obtained from the larvae did not match any available Boccardia sequences, but this species is very similar to the other Boccardia species in larval morphology and gene sequences (Figs 2, 3). Therefore, this species was referred to Boccardia sp. 1.

Planktonic larvae of this species were collected from Onagawa Bay in April, May, November, and December 2011, and January, February, March, and May 2012. The overall body shape of these larvae is slender and slightly fusiform, similar to those of B. proboscidea . However, other larval morphological characteristics differ between these two species: overall body color is faint yellow in the former species and faint green in the latter; the larval chaetae are longer in the former species than in the latter, especially in early larvae (Fig. 7D); lateral black spots are present on chaetiger V onwards in the former species but only on chaetigers VII and VIII in the latter species.