Boccardia sp. 1

Abe, Hirokazu & Sato-Okoshi, Waka, 2021, Molecular identification and larval morphology of spionid polychaetes (Annelida, Spionidae) from northeastern Japan, ZooKeys 1015, pp. 1-86 : 1

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.

Figures

Figure 2. Maximum Likelihood tree inferred from nuclear 18 S and mitochondrial 16 S rRNA gene sequences of spionids obtained from Japan in the present and previous studies (provided in Table 1). The gene sequences of adult and larval spionid polychaetes are indicated by solid squares and circles in front of each species name, respectively. SH-aLRT / approximate Bayes support / ultrafast bootstrap support values of ≥ 80 %, ≥ 0.95, ≥ 95 %, respectively are given beside the respective nodes. Nodes with red circles indicate triple high support values of SH-aLRT ≥ 80, approximate Bayes support ≥ 0.95, and ultrafast bootstrap support ≥ 95. The scale bar represents the number of substitutions per site. Sequences of Laonome sp. and Sabella pavonina Savigny, 1822 obtained from DDBJ / EMBL / GenBank were used for outgroup rooting.

Figure 3. Maximum Likelihood tree inferred from nuclear 18 S and mitochondrial 16 S rRNA gene sequences of spionid polychaetes obtained from Japan in the present and previous studies (shown in Table 1) and from DDBJ / EMBL / GenBank (shown in Table 2). The tree is divided into two parts A, B. The gene sequences obtained in the present study are highlighted by bold and red color and the adult and larval sequences are indicated by solid squares and circles in front of each species name, respectively. SH-aLRT / approximate Bayes support / ultrafast bootstrap support values of ≥ 80 % / ≥ 0.95 / ≥ 95 %, respectively are given beside the respective nodes. Nodes with red circles indicate triple high support values of SH-aLRT ≥ 80, approximate Bayes support ≥ 0.95, and ultrafast bootstrap support ≥ 95. The scale bar represents the number of substitutions per site. Sequences of Laonome sp. and Sabella pavonina Savigny, 1822 obtained from GenBank were used for outgroup rooting.

Figure 7. Light micrographs showing the morphologies of living spionid larvae of genera Boccardia, Boccardiella, and Dipolydora A, B Boccardia proboscidea, dorsal view of accidentally hatched 9 - chaetiger (A) and 15 - chaetiger larvae (B) C Boccardia pseudonatrix, dorsal (left) and ventral (right) view of accidentally hatched 10 - chaetiger larvae D-F Boccardia sp. 1, dorsal view of 9 - chaetiger (D) and dorsal (E) and ventral view (F) of 17 - chaetiger larvae G Boccardia sp. 2, dorsal view of 15 - chaetiger larva H, I Boccardiella hamata, dorsal view of 16 - chaetiger (H) and 18 - chaetiger larvae (I) J, K Dipolydora bidentata, dorsal view of 13 - chaetiger (J) and 18 - chaetiger larvae (K) L Dipolydora cf. commensalis, dorsal view of 21 - chaetiger larva M, N Dipolydora giardi, dorsal view of 19 - chaetiger (M) and lateral view of 21 - chaetiger larvae (N) O Dipolydora cf. socialis, dorsal view of 18 - chaetiger larva P Dipolydora sp., dorsal view of 7 - chaetiger larva. Scale bars: 300 μm.