Neanthes babuzai Hsueh 2019, n. sp.

Neanthes babuzai n. sp.

Figs 1 A–G, 2A–E, Table 2

Material examined. Holotype (NMNS 7946-001), Xianxi (24°09.56´N 120°37.55´E), Changhua County, Taiwan, intertidal muddy bottom, 22 April 2017. Paratypes: 15 specimens (NMNS 7946-002 – 011; AM W.51458; NTM W29677), collection location, habitat and date information same as holotype; 1 specimen (NMNS 7946-012), Wanggong (23°58.08´N 120°19.45´E), Changhua County, Taiwan, intertidal muddy bottom, 17 March 2007; 1 specimen (NMNS 7946-013), Fufong Bridge (24°01.66´N 120°22.78´E), Changhua County, Taiwan, intertidal muddy bottom, 18 March 2007.

Description. Holotype, complete, body length 131.0 mm (35.0–226.0, n=11 complete specimens) with 161 (106–187, n=11) chaetigers, maximum width 2.5 mm (4.5–7.2, n=11) at chaetiger 5 (5–9, n=11), excluding parapodia; light brown in alcohol (Fig. 1A). Prostomium about equal in length and width, one pair antennae arise antero-laterally; palpophores spherical and biarticulate with sub-conical palpostyles, four pairs of tentacular cirri present, longest posterior tentacular cirri reaching chaetiger 5 (5–9, n=12) (Fig. 1B). Two pairs of black eyes, in trapezoidal arrangement, subequal in size. One apodous anterior segment (= peristomium) present, about 1.7 times (about 1.2–1.7, n=8) as long as chaetiger 1. Pharynx with dark brown jaws, each 7–8 (6–10, n=12) lateral teeth; dark conical paragnaths as: I=6 (3–7, n=12, sample size of Areas II to VIII same as Area I), 5 paragnaths in a longitudinal line with 1 paragnath aside (in triangle, diamond-shaped or a cluster with 3, 4 & 5–7 paragnaths, respectively); II=15(16–26) (left), 16 (11–25) (right), in 2 crescentic rows; III=57 (45–63), in 4–7 transverse rows; IV=15 (16–28) (left), 22 (11–27) (right), in 2 crescentic rows; V = 3 (2), in a triangle (in a longitudinal line with 2); VI=2 (2–4) (left), 2 (2–3) (right), in a transverse row; VII/VIII=57 (35–66), in 2–3 rows (Fig. 1C).

Notopodial dorsal ligule triangular with a pointed tip on anterior chaetigers, narrowed triangular with a pointed tip on posterior chaetigers (Fig. 1 D–G). Dorsal cirri attached to dorsal edge 1/3 from base of dorsal ligule on anterior chaetigers, attached basally to dorsal ligule on posterior chaetigers, shorter than dorsal ligule throughout (Fig. 1 D–G). Notopodial ventral ligule narrowed triangular with a pointed tip throughout. Neuropodium with prominent inferior lobe on anterior chaetigers, becoming less developed on posterior chaetigers. Neuropodial superior lobe present, inconspicuous on anterior chaetigers, about as long as inferior lobe on posterior chaetigers. Neuropodial postchaetal lobe present, rounded triangular with a pointed tip on anterior chaetigers, triangular with a pointed tip on posterior chaetigers. Neuropodial ventral ligule digitiform throughout; ventral cirri basally attached to neuropodial ventral ligule on anterior chaetigers, basally attached to ventral edge of parapodia, shorter than ventral ligule throughout (Fig. 1 D–G).

Notochaetae present from chaetiger 3 to posterior end, homogomph spinigers (Fig. 2A). Neurochaetae dorsal fascicle: homogomph spinigers (Fig. 2B), and heterogomph falcigers with long, basally serrated terminal blade (Fig. 2C). Neurochaetae ventral fascicle: heterogomph spinigers (Fig. 2D) and heterogomph falcigers with long basally serrated terminal blade (Fig. 2E). Pygidium round, one pair of filamentous anal cirri attached ventrally, extending about 15 (8–24, n=8) chaetigers.

Etymology. The name is derived from the Babuza, an aboriginal tribe lived in the Changhua area during the prehistoric ages of Taiwan.

Type locality. Xianxi, Changhua County, Taiwan.

Distribution. Only known from the type locality and two other coastal locations in Changhua County, Taiwan.

Remarks. Of the 22 Neanthes species reported from East and Southeastern Asia, only N. donghaiensis Wu, Sun & Yang, 1981 from China and N. vitabunda (Pflugfelder, 1933) from Indonesia were recorded with 2–3 conical paragnaths on Area V of the pharynx as in N. babuzai n. sp. (Pflugfelder 1933: 72, fig. 12b; Wu et al. 1981: 132; Table 2). Neanthes babuzai n. sp., however, differs from N. donghaiensis by having greater numbers of conical paragnaths on Areas III & VII/VIII of the pharynx (49–63 & 51–66 versus 20–30 & 20–30, respectively) (Wu et al. 1981: 132; Table 2). Neanthes babuzai n. sp., can be distinguished from N. vitabunda by having greater numbers of conical paragnaths on Areas II, III & VII/VIII of the pharynx (11–25, 49–63 & 51–66 versus 6, 27 & 40, respectively) (Pflugfelder 1933: 72, fig. 12b; Table 2). Moreover, N. babuzai n. sp. has 3 types of neurochaetae (i.e., homogomph spinigers, heterogomph spinigers and heterogomph falcigers; Fig. 2 A–E; Table 2), but N. vitabunda has only two types of neurochaetae (i.e., homogomph spinigers and heterogomph falcigers; Pflugfelder 1933: 72, fig. 12d). Neanthes babuzai n. sp. is one of the three species reported in the present study, which has 3 conical paragnaths on Area V of the pharynx. The other two species are: N. jihueiensis n. sp. (n=2) and N. kinmenensis n. sp. (n=3). However, N. babuzai n. sp. differs from these two species by having a greater number of conical paragnaths on Area III of the pharynx (45–63 versus 15–18, 28–31 & 17–21, respectively) (Table 2). Neanthes babuzai n. sp. can also be distinguished from N. jihueiensis n. sp. by having long neuropodial heterogomph falcigers, whereas that of N. jihueiensis n. sp. is medium-length heterogomph falcigers (Figs 2C, E, 6C, E; Table 2). Neanthes babuzai n. sp. can also be distinguished from N. kinmenensis n. sp. by having dorsal cirri attached 1/3 from base of dorsal ligule, but that of N. kinmenensis n. sp. attached at base of dorsal ligule (Figs 1D, E, 9D, E; Table 2).