Laonice sp. 2

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

Laonice sp. 2 Fig. 4E

Larval morphology.

Late larvae thick and stumpy in shape (Fig. 4E ). Prostomium stumpy, somewhat notched at tip. Lateral parts of peristomium well demarcated from prostomium. In late larvae, two pairs of red eyes are arranged in a trapezoidal shape, the medial pair bigger and situated anteriorly. Short palps developed in late larvae, attached to outer end of lateral parts of peristomium. Parapodia weakly differentiated; serrated larval chaetae in both noto- and neuropodia; notochaetae characteristically introverted toward medial line of dorsal side. Gut dark green in color internally. Pigmentation absent except in the eyes.

Remarks.

Adult individuals of this species were not collected in the present study. Only one individual of larva of this species were collected in Habu Port in June 2016. Even though the 18S and 16S rRNA gene sequences were not obtained, the larvae were identified as belonging to Laonice because the larval morphology of this species agrees with that of L. cirrata described by Hannerz (1956) and L. cf. cirrata described by Plate and Husemann (1994). However, the hooded hooks in neuropodia described by Hannerz (1956) were not observed in the specimens of the present study (nor in those reported by Plate and Husemann [1994]); this may be because the larvae collected here were less developed and the hooks were reported only from chaetiger XIV onwards.

Figures

Figure 4. Light micrographs showing morphologies of living spionid larvae of Aonides, Laonice, Rhynchospio, Scolelepis, and Spiophanes A-C Aonides cf. oxycephala, dorsal view of early planktonic (A), 8 - chaetiger (B), and 18 - chaetiger larvae (C) D Laonice sp. 1, dorsal view of early planktonic larva E Laonice sp. 2, dorsal view of 12 - chaetiger larva F Poecilochaetus sp., dorsal view of 17 - chaetiger larva G, H Rhynchospio aff. asiatica, dorsal view of 6 - chaetiger (G) and 12 - chaetiger larvae (H) I Scolelepis cf. kudenovi, dorsal view of 7 - chaetiger larva J, K Scolelepis sp. 1, dorsal view of 17 - chaetiger (J) and 19 - chaetiger larvae (K) L Scolelepis sp. 2, dorsal view of 20 - chaetiger larva M, N Spiophanes uschakowi, dorsal (M) and lateral view (N) of 18 - chaetiger larvae O, P Spiophanes aff. uschakowi, dorsal view of 16 - chaetiger larva (O) and 27 - chaetiger juvenile (P). Scale bars: 300 μm.