Neanthes jihueiensis, Hsueh, 2019

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 : 179-180

Neanthes jihueiensis n. sp.

Figs 5A – G , 6A – E , Table 2

Material examined. Holotype ( NMNS 7946-016 ), Jihuei (23°06.86´N 121°24.18´E), Taitung County, Taiwan, rocky intertidal hard bottom, 28 April 2017 . Paratype: 1 specimen ( NMNS 7946-017 ), collection location and habitat information same as holotype, 29 April 2017 .

Description. Holotype, incomplete, posterior end missing, remaining body length 94.5 mm (45.5) with 121 (86) chaetigers, maximum width 2.5 mm (1.5) at chaetiger 5 (6), excluding parapodia; brown to beige in alcohol ( Fig. 5A ). Prostomium wider than long, one pair antennae arise antero-laterally, palpophores spherical and biarticulate with sub-conical palpostyles, four pairs of tentacular cirri, longest posterior tentacular cirri reaching chaetiger 4 ( Fig. 5B ). Two pairs of black eyes, in trapezoidal arrangement, subequal in size. One apodous anterior segment present, about 1.2 times as long as chaetiger 1. Pharynx with dark brown jaws, each with 4 lateral teeth; brown to dark conical paragnaths as: I=3 (2), in a triangle (in longitudinal line with 2); II=8 (11) (left), 12 (13) (right), in 2 oblique rows; III=15 (18), in 2–3 transverse rows; IV=28 (23) (left), 34 (25) (right), in 4–5 oblique rows; V=3, in a triangle ( Fig. 5C ); VI=2 (3) (left), 3 (right), in a transverse row; VII/VIII=18 (27), in 2–3 rows.

Notopodial dorsal ligules rounded on anterior chaetigers, narrowed triangular with a pointed tip on posterior chaetigers ( Fig. 5 D–G). Dorsal cirri basally attached to dorsal ligule on anterior chaetigers, mid-dorsally attached to dorsal ligule on posterior chaetigers; about as long as dorsal ligule on anterior chaetigers, shorter than dorsal ligule on posterior chaetigers ( Fig. 5 D–G). Notopodial ventral ligule conical on anterior chaetigers, narrowed triangular with a blunt tip on posterior chaetigers. Neuropodium with prominent inferior lobe and less developed superior lobe on anterior chaetigers, both lobes less developed on posterior chaetigers. Neuropodial postchaetal lobe absent. Neuropodial ventral ligule conical on anterior chaetigers, narrowed triangular with a pointed tip on posterior chaetigers; ventral cirri mid-ventrally attached to ventral edge of parapodia, shorter than ventral ligule ( Fig. 5 D–G).

Notochaetae present from chaetiger 3 to posterior chaetigers, homogomph spinigers ( Fig. 6A ). Neurochaetae dorsal fascicle: homogomph spinigers ( Fig. 6B ), and heterogomph falcigers with medium-length, serrated terminal blade ( Fig. 6C ). Neurochaetae ventral fascicle: heterogomph spinigers ( Fig. 6D ), and heterogomph falcigers with medium-length, serrated terminal blade ( Fig. 6E ). Pygidium not observed.

Etymology. The name is derived from the name of a coastal village, Jihuei, where the worm was collected.

Type locality. Jihuei , Taitung County, Taiwan .

Distribution. Only known from the type locality.

Remarks. Neanthes jihueiensis n. sp. has 3 conical paragnaths on Area V of the pharynx, which is also seen in N. donghaiensis and N. vitabunda reported from China and Philippines, respectively ( Pflugfelder 1933: 72, fig. 12b; Wu et al. 1981: 132; Table 2). Neanthes jihueiensis n. sp., however, is readily distinguished from the latter two species by having neuropodial heterogomph falcigers with medium-length terminal blade, whereas that of the latter two species is long terminal blade ( Pflugfelder 1933: 72, fig. 12d; Wu et al. 1981: 133, fig. 82H; Fig. 6C, E ). Of the nine species reported in the present study, two have 3 conical paragnaths on Area V of the pharynx as in N. jihueiensis n. sp.: N. babuzai n. sp. (n=18) and N. kinmenensis n. sp. (n=2) ( Table 2). Neanthes jihueiensis n. sp., however, differs from these two species by having fewer conical paragnaths on Area VII/VIII (18–27 versus 35 and up) and neuropodial heterogomph falcigers with a medium-length terminal blade (versus a long terminal blade) ( Figs 2C, E , 6C, E , 10C, E ; Table 2).

Figures

FIGURE 2. Neanthes babuzai n. sp.; holotype (NMNS 7946-001): A, notochaeta, homogomph spiniger, chaetiger 142; B, neurochaeta of dorsal fascicle, homogomph spiniger, chaetiger 129; C, neurochaeta of dorsal fascicle, long heterogomph falciger, chaetiger 129; D, neurochaeta of ventral fascicle, heterogomph spiniger, chaetiger 129; E, neurochaeta of ventral fascicle, long heterogomph falciger, chaetiger 129. Scale: A–E, 0.05 mm.

FIGURE 5. Neanthes jihueiensis n. sp.; holotype (NMNS 7946-016): A, whole animal; B, anterior body; C, paragnaths of the pharynx; D, right parapodium, anterior view, chaetiger 10; E, right parapodium, posterior view, chaetiger 10; F, right parapodium, anterior view, chaetiger 121; G, right parapodium, posterior view, chaetiger 121. Scale: A, 10.0 mm; B, 1.0 mm; C–G, 0.5 mm.

FIGURE 6. Neanthes jihueiensis n. sp.; holotype (NMNS 7946-016): A, notochaeta, homogomph spiniger, chaetiger 121; B, neurochaeta of dorsal fascicle, homogomph spiniger, chaetiger 121; C, neurochaeta of dorsal fascicle, medium heterogomph falciger, chaetiger 121; D, neurochaeta of ventral fascicle, heterogomph spiniger, chaetiger 121; E, neurochaeta of dorsal fascicle, medium heterogomph falciger, chaetiger 121. Scale: A–L, 0.05 mm.

FIGURE 10. Neanthes kinmenensis n. sp.; holotype (NMNS 7946-027): A, notochaeta, homogomph spiniger, chaetiger 82; I, neurochaeta of dorsal fascicle, homogomph spiniger, chaetiger 82; J, neurochaeta of dorsal fascicle, heterogomph falciger, chaetiger 82; K, neurochaeta of ventral fascicle, heterogomph spiniger, chaetiger 82; L, neurochaeta of ventral fascicle, heterogomph falciger, chaetiger 82. Scale: A–E, 0.05 mm.