Neanthes, Kinberg, 1865

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 : 191-196

Neanthes sp. 1

Figs 17A – G , 18A – F , Table 2

Material examined. One specimen (NMNS 7946-035), Jihuei (23°06.86´N; 121°24.18´E), Taitung County, Taiwan, intertidal hard bottom, 7 October 2010.

Description. Incomplete, in two fragments, remaining body length 38.0 mm with 70 chaetigers, maximum width 2.2 mm at chaetiger 8, excluding parapodia; dark brown to beige in alcohol ( Fig. 17A ). 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 5 ( Fig. 17A ). Two pairs of black eyes, subequal in size. One apodous anterior segment present, about 1.4 times as long as chaetiger 1. Pharynx with dark brown jaws, each with 6–7 lateral teeth; dark conical paragnaths as: I=8 ( Fig. 17B ); II=20, 23, in 2–3 oblique rows; III=30, in a cluster; IV= 23, 29 in 2–3 oblique rows; V=4 (3 large cones+1 minute cone), in a triangle; VI=2, 2, in a transverse row ( Fig. 17C ); VII/VIII=45, in 2–3 transverse row.

Notopodial dorsal ligule conical on anterior chaetigers, narrowed triangular with a pointed tip in posterior chaetigers; basal dorsal edge of dorsal ligule slightly broaden on posterior chaetigers ( Fig. 17 D–G). Dorsal cirri mid-dorsally attached to dorsal ligule throughout, shorter than dorsal ligule ( Fig. 17 D–G). Notopodial prechaetal lobe present on anterior chaetigers, small oval ( Fig. 17D ). Notopodial ventral ligule rounded on anterior chaetigers, narrow and triangular on posterior chaetigers. Neuropodium with prominent inferior and superior lobes on anterior chaetigers, both lobes projecting beyond neuropodial postchaetal lobe on anterior chaetigers, both inferior and superior lobes absent on posterior chaetigers. Neuropodial postchaetal lobe present, conical on anterior chaetigers, triangular with a pointed tip on posterior chaetigers, shorter than neuropodial acicular ligule ( Fig. 17 D–G). Neuropodial postchaetal lobe present, rounded on anterior chaetigers, triangular with a blunt tip on posterior chaetigers. Neuropodial ventral ligule conical on anterior chaetigers, narrowed triangular with a pointed tip on posterior chaetigers; ventral cirri attached to ventral edge of parapodia, shorter than ventral ligule on anterior chaetigers, about as long as ventral ligule on posterior chaetigers ( Fig. 17 D–G).

Notochaetae present from chaetiger 3 to posterior chaetigers, homogomph spinigers ( Fig. 18A ). Neurochaetae dorsal fascicle: homogomph spinigers ( Fig. 18B ), and heterogomph falcigers with short, serrated terminal blade ( Fig. 18C ). Neurochaetae ventral fascicle: heterogomph spinigers ( Fig. 18D ), and heterogomph falcigers with short, serrated terminal blade on anterior chaetigers ( Fig. 18E ), and medium-length, serrated terminal blade on posterior chaetigers ( Fig. 18F ). Pygidium not observed.

Remarks. The specimen is recorded as an undetermined species due to its small body size and incomplete specimen condition. Of the 22 Neanthes species reported from East and Southeast Asia, N. vitabunda from Philippines is the only species which has somewhat similar counts of conical paragnaths on most areas of the pharynx as in N. sp. 1 (6, 27, 29–34, 3, 2 & 40 versus 8, 30, 23–29, 4, 2 & 45, respectively), with an exception of Area II (6 versus 20–23) ( Pflugfelder 1933: 72, fig. 12b; Table 2). However, N. sp. 1 can be distinguished from N. vitabunda by having the longest posterior tentacular cirri reaching chaetiger 5 (versus posterior of peristomium), notopodial prechaetal lobe on anterior chaetigers, heterogomph spinigers on ventral fascicle of the neuropodia (versus none), and short and medium heterogomph falcigers in neuropodia (versus long heterogomph falcigers) ( Pflugfelder 1933: 72, fig. 12a, d; Fig. 22C–F, Table 2). Of the five species that have notopodial prechaetal lobe on anterior chaetigers in the present study, N. sp. 1 is the only species with 4 conical paragnaths on Area V of the pharynx ( Table 2). Neanthes sp. 1 is also the only species, which has both short and medium-length heterogomph falcigers in neuropodia ( Table 2).

cricognatha (Ehlers, 1904) with N. acuminata ( Ehlers, 1868) . A=brackish aquaculture farm, B=salt pan, C=oyster racks, D=intertidal hard bottom, E=intertidal soft bottom,

F=subtidal soft bottom, G=abyssal soft bottom; H=coastal brackish water lake, n.a.=not available.

Species\Categories P/Ch1 RCLPTC LTJ Paragnaths

I II (left, right) III IV (left, right) V VI VII/VIII N. babuzai n. sp. ~1.2–1.7 5–9 6–10 3–7 15–26, 11–25 45 –63 16–28, 11– 27 2–3 2–3, 2–4 35 – 66 N. donggungensis n. sp. ~1.4 6–7 7–9 2 8–9, 10– 11 12–15 15 –17, 17 0 7–10, 7–13 76 – 91 N. jihueiensis n. sp. ~1.2 4 4 2–3 8–11, 12–13 15–18 23–28, 25–34 3 2–3, 3 18– 27 N. kaomeiensis n. sp. ~1.1 7–9 4–6 6–7 9–12, 8–12 30–36 8–11, 8–12 0 1, 1 0 N . kinmenensis n. sp. ~1.4 2 5–6 3–4 10 –13, 11–15 28–31 22–24, 20– 23 3 2, 2– 3 46 N. cf. nanhaiensis Wu, Sun & Yang, 1981 ~1.1 2 10–12 0 6–7, 8–9 1–3 7–9, 8–13 0 0 1/0 N. sanguensis n. sp. ~1.3 4 7 1 12, 15 10 17, 18 1 2, 2 33 N . shigungensis n. sp. ~1.3 3 6–7 7 24, 27 65 25, 32 7–8 3, 3 57– 58 N. sp. 1 ~1.4 5 6–7 8 20, 23 30 23, 29 4 2, 2 45

Figures

FIGURE 17. Neanthes sp. 1 (NMNS 7946-035): A, anterior body; B, Area I of the pharynx; B, Areas V & VI of the pharynx; D, right parapodium, anterior view, chaetiger 10; E, right parapodium, posterior view, chaetiger 10; F, right parapodium, anterior view, posterior chaetiger; G, right parapodium, posterior view, posterior chaetiger. Abbreviation: NoPL, notopodial prechaetal lobe. Scale: A, 1.0 mm; B, 0.5 mm; C–G, 0.1 mm; H–M, 0.05 mm.

FIGURE 18. Neanthes sp. 1 (NMNS 7946-035): A, notochaeta, homogomph spiniger, posterior chaetiger; B, neurochaeta of dorsal fascicle, homogomph spiniger, posterior chaetiger; C, neurochaeta of dorsal fascicle, medium heterogomph falciger, posterior chaetiger; D, neurochaeta of ventral fascicle, heterogomph spiniger, posterior chaetiger; E, neurochaeta of ventral fascicle, short heterogomph falciger, chaetiger 10; F, neurochaeta of ventral fascicle, medium heterogomph falciger, posterior chaetiger. Scale: A–F, 0.05 mm.