Nereis shitipingensis, Hsueh, 2020

Hsueh, Pan-Wen, 2020, New species of Nereis (Annelida, Polychaeta, Nereididae) from Taiwanese waters, Zootaxa 4802 (1), pp. 1-31 : 16-17

Nereis shitipingensis n. sp.

Figs 9A–D, 10A–E

Material examined. Holotype ( NMNS 8174-005 ), Shitiping (23°28.96´N 121°30.78´E), Hualien County, Taiwan, intertidal vegetated hard bottom, 27 August 2010.

Description. Holotype (NMNS 8174-005), complete, body length 21.5 mm with 51 chaetigers, maximum width 1.0 mm at chaetiger 7, excluding parapodia; beige in alcohol (Fig. 9A). Prostomium wider than long, lateral antennae antero-lateral; palpophores globose, palpostyles conical, four pairs of tentacular cirri, surface smooth, longest one reaching chaetiger 4 (Fig. 9B). Two pairs of eyes, in trapezoidal arrangement, subequal in size. Apodous anterior segment about 1.2 times as long as chaetiger 1. Pharynx with light brown jaws, each with 7–8 teeth; I=2; II=17 (left), 17 (right), in 4 oblique rows; III=33, in 3 transverse rows; IV=27 (left), 32 (right), in 4–5 oblique rows; V=0; VI=10 (left), 10 (right), in 2 transverse rows; VII/VIII=14, in 2 rows (Fig. 9C).

Notopodial dorsal ligules conical with a rounded tip on anterior chaetigers (Fig. 9D), narrow triangular with a pointed tip on posterior chaetigers. Dorsal cirri basally attached to dorsal ligules throughout, about 3.0 times as long as dorsal ligules throughout (Fig. 9D). Notopodial prechaetal lobes absent. Notopodial ventral ligules conical on anterior chaetigers, narrow triangular with a pointed tip on mid-body to posterior chaetigers (Fig. 9D). Neuropodial postchaetal lobes absent. Neuropodial ventral ligules conical on anterior chaetigers, narrow triangular with a pointed tip on mid-body to posterior chaetigers; ventral cirri attached to ventral edge of parapodia on mid-body to posterior chaetigers throughout, about as long as ventral ligules throughout (Fig. 9D).

Notochaetae present from chaetiger 3 to posterior end, homogomph spinigers present on anterior chaetigers (Fig. 10A), homogomph falcigers present from chaetiger 24 to posterior end, blade slightly incurved at base, acute, with long serrations (Fig. 10B). Neurochaetae upper fascicle: homogomph spinigers present (Fig. 10C), heterogomph falcigers with serrated short-blade (Fig. 10D). Neurochaetae ventral fascicle: heterogomph spinigers absent, heterogomph falcigers with serrated short-blade (Fig. 10E). Pygidium round, one pair of filamentous anal cirri attached ventrally, as long as last six chaetigers (Fig. 9A).

Etymology. The name is derived from the name of nearby village, Shitiping, where the worm was collected.

Type locality. Shitiping , Hualien County, Taiwan .

Distribution. Only known from the type locality.

FIG. 10. Nereis shitipingensis n. sp.; holotype (NMNS 8174-005): A, chaetiger 30, notochaetal homogomph spiniger; B, same, notochaetal homogomph falciger; C, same, neurochaetal upper fascicle, homogomph spiniger; D, chaetiger 8, neurochaetal ventral fascicle, short-bladed heterogomph falciger; E, chaetiger 30, neurochaetal ventral fascicle, short-bladed heterogomph falciger. Scale: A–C, 0.025 mm; D, E, 0.01 mm.

Remarks. Of the 36 Nereis species reported from East and the present study, fourteen species share a morphological feature of having Areas VII & VIII with 1or 2 transverse rows of paragnaths, which are: N. coutieri Gravier, 1899 , N. dayana Shen & Sun in Sun, Wu & Shen, 1978 , N. denhamensis Augener, 1913 , N. falcaria ( Willey, 1905) , N. falcaria multignatha Wu, Sun & Yang, 1981 , N. heteromorpha Horst, 1924 , N. huanghaiensis Wu, Sun & Yang, 1981 , N. jacksoni Kinberg, 1866 , N. nichollsi Kott, 1951 , N. shitipingensis n. sp., N. sinensis Wu, Sun & Yang, 1981 , N. taitungensis n. sp., N. taiwanensis n. sp., and N. zhongshaensis Shen & Sun in Sun, Wu & Shen,1978 (see the Key provided in the present study). Of these 14 species, only N. nichollsi and N. shitipingensis n. sp. have more than 30 paragnaths on Area III and blade of notopodial homogomph falcigers with long serrations and slightly incurved at base ( Imajima 1972: 123–124, fig. 39 m, 1996: 150, fig. 119i; Fig. 10B, Table 2). However, N. shitipingensis n. sp. differs from N. nichollsi by having: 1) longest tentacular cirri reaching chaetiger 4 (versus chaetiger 2); 2) 33 paragnaths arranged in 3 transverse rows on Area III (versus 41 paragnaths arranged in 4 rows); 3) 14 conical paragnaths arranged in 2 transverse rows on Areas VII & VIII (versus 15 conical and longitudinal flatten paragnaths interspaced arranged in 1 transverse row); 4) dorsal cirri about 3.0 times as long as dorsal ligules on anterior chaetigers (versus about 4.0 times); and 5) notopodial dorsal ligules not elongated on all chaetigers (versus elongated on mid-body and posterior chaetigers ( Imajima 1972: 123–124, fig. 39a-h, j, k, 1996: 150, fig. 119a-g; Fig. 9A–D, Table 2).