Neanthes cf. nanhaiensis Wu, Sun & Yang, 1981

Hsueh, Pan-Wen, 2019, Neanthes (Annelida: Nereididae) from Taiwanese waters, with description of seven new species and one new species record, Zootaxa 4554 (1), pp. 173-198 : 186-188

Neanthes cf. nanhaiensis Wu, Sun & Yang, 1981

Figs 11A – F , 12A – F , Table 2

Material examined. Two specimens (NMNS 7946-029), station C2 (25°12.78´N 121°23.5´E), Bali, New Taipei City, Taiwan, subtidal muddy bottom, 9 January 2015.

Description. Incomplete, posterior body missing, remaining body length 15.0 mm (12.0) with 34 (37) chaetigers, maximum width 1.5 mm (1.0) at chaetiger 6 (4), excluding parapodia; beige in alcohol ( Fig. 11A ). Prostomium wider than long, one pair antennae arise antero-laterally; palpophores spherical and biarticulate with sub-conical palpostyles, four pairs of tentacular cirri present. Two pairs of purple red eyes, in trapezoidal arrangement, anterior pair slightly larger than posterior pair. One apodous anterior segment present, about 1.1 times as long as chaetiger 1. Pharynx with brownish jaws, each with 5–6 lateral teeth; dark conical paragnaths as: I=0; II=6 (7) (left), 9 (8) (right), in 2–3 oblique rows; III=3 (1), in a transverse row; IV=9 (7) (left), 13 (8) (right), in a cluster; V=0; VI=0; VII=1; VIII=0 ( Fig. 11A, B ).

Notopodial dorsal ligule digitiform on anterior chaetigers, narrowed triangular with a pointed tip on posterior chaetigers ( Fig. 11 C–F). Dorsal cirri attached basally to dorsal notopodial ligule throughout, about as long as dorsal ligule. Notopodial prechaetal lobe present on chaetiger 3 to 25, about 2/3 as long as notopodial ventral ligule ( Fig. 11C, D ). Notopodial ventral ligule digitiform throughout. Neuropodial postchaetal lobe present, digitiform projecting beyond neuropodial acicular ligule. Neuropodial ventral ligule digitiform; ventral cirri basally attached to base of ventral ligule, shorter than ventral ligule ( Fig. 11 C–F).

Notochaetae present on chaetiger 3 to posterior chaetigers, homogomph spinigers ( Fig. 12A ). Neurochaetae dorsal fascicle: homogomph spinigers ( Fig. 12B ), and heterogomph falcigers with medium-length, serrated terminal blade ( Fig. 12C ). Neurochaetae ventral fascicle: homogomph spinigers ( Fig. 12D ), heterogomph falcigers with medium-length ( Figs. 12C, E ) and long, serrated terminal blade ( Fig. 12F ). Pygidium not observed.

Distribution. South China Sea, northeastern Taiwan Strait.

Remarks. The two specimens examined in the present study are very similar to N. cf. nanhaiensis from China in terms of: 1) number of lateral teeth on jaws, 2) paragnath patterns, 3) the presence/absence of prechaetal lobe on anterior chaetigers, 4) types of notopodial and neuropodial chaetigers. Both species have 5 to 6 lateral teeth on jaws. The paragnath pattern of the present specimens is the same as that of N. cf. nanhaiensis on Areas I, III & V– VIII, with a slightly different in the range of conical paragnath numbers on Areas II & IV ( Table 2). Both species have prechaetal lobes on anterior chaetigers, notopodial and neuropodial homogomph spinigers, medium and long neuropodial heterogomph falcigers ( Wu et al. 1981: 139–140, figs 86A–E, G, H; Figs 11D , 12 A–F). Additionally, both species were collected from subtidal soft bottom habitats ( Wu et al. 1981: 139). Few minor differences between the two are: 1) the present specimens have more slender notopodial and neuropodial ligules than that of N. cf. nanhaiensis , 2) dorsal cirri of the present specimens are about as long as the dorsal ligule, whereas those of N. cf. nanhaiensis are longer than the dorsal ligule ( Wu et al. 1981: 139–140, fig. 86A–E, G, H; Fig. 12 C–F). However, the latter difference may be due to specimen damage as tip of dorsal cirri in the present specimens were broken off during the trawling process.

Figures

FIGURE 11. Neanthes cf. nanhaiensis Wu, Sun & Yang, 1981 (NMNS 7946-029): A, anterior body, dorsal view; B, anterior body, ventral view; C, left parapodium, anterior view, chaetiger 5; D, left parapodium, posterior view, chaetiger 5; E, left parapodium, anterior view, chaetiger 34; F, left parapodium, posterior view, chaetiger 34. Abbreviation: NoPL, notopodial prechaetal lobe. Scale: A–B, 1.0 mm; C–F, 0.1 mm.

FIGURE 12. Neanthes cf. nanhaiensis Wu, Sun & Yang, 1981 (NMNS 7946-029): A, notochaeta, homogomph spiniger, chaetiger 32; B, neurochaeta of dorsal fascicle, homogomph spiniger, chaetiger 32; C, neurochaeta of dorsal fascicle, medium heterogomph falciger, chaetiger 32; D, neurochaeta of ventral fascicle, homogomph spiniger, chaetiger 32; E, neurochaeta of ventral fascicle, medium heterogomph falciger, chaetiger 32; F, neurochaeta of ventral fascicle, long heterogomph falciger, chaetiger 32. Scale: A–B, D, 0.05 mm; C, E–F, 0.01 mm.