Neanthes hsinchuensis, Hsueh, 2019

Hsueh, Pan-Wen, 2019, Two new species of nereidids (Annelida, Polychaeta) from Taiwan, Zootaxa 4652 (3), pp. 544-556 : 552-555

Neanthes hsinchuensis n. sp.

Figs 5A – I , 6A – F , Table 2

Material examined. Holotype ( NMNS 8064-001 ), Hsinchu fishing port (24°51.00´N 121°55.48´E), Hsinchu City, Taiwan, fouling community on docks of fishing port, 18 July 2016.

Diagnosis. Neanthes with short tentacular cirri (reaching chaetiger 3). Jaws dark brownish, each with 3 lateral teeth; conical paragnaths on maxillary and oral rings of pharynx as: Area I=2; Area II=14 (left), 12 (right); Area III=29; Area IV=3 (left), 4 (right); Area V=0; Area VI =3 (left), 4 (right); Area VII/VIII=12. Notopodial ligule markedly elongated and broader basally along middle to posterior chaetigers. Notopodial prechaetal lobe absent. Notochaetae: homogomph spinigers. Neurochaetae homogomph and heterogomph spinigers, short bladed heterogomph falcigers. Neurochaetae heterogomph spinigers, short bladed heterogomph falcigers.

Description. Holotype ( NMNS 8064-001), complete, ovigerous female, 80.0 mm long with 106 chaetigers, maximum width 3.5 mm at chaetiger 6, excluding parapodia; brown in alcohol ( Fig. 5A ). Prostomium longer than wide, one pair antennae arise antero-laterally, palps biarticulate, palpophores subcylingdrical, palpostyles sub-conical, four pairs of tentacular cirri, longest posterior tentacular cirri reaching chaetiger 3 ( Fig. 5B ). Two pairs of black eyes, in trapezoidal arrangement, anterior eyes slightly smaller than posterior ones. One apodous anterior segment present, about 1.4 times as long as chaetiger 1. Pharynx with dark brown jaws, each with 3 lateral teeth; brown to dark conical paragnaths as: I=2, in longitudinal line; II=14 (left), 12 (right), in 3–4 oblique rows; III=29, in 3–4 transverse rows; IV=24 (left), 26 (right), in 4–5 oblique rows; V=0; VI =3 (left), 4 (right), in a transverse row ( Fig. 5C ); VII/VIII=12, in 2 rows.

Chaetigers 1–15 with notopodial dorsal ligules triangular with rounded tips, narrow triangular with acute point- ed tips along chaetigers 16 to 23, then digitiform along chaetigers 24 to 104, and blunt triangular on last two chaetigers ( Fig. 5 D–I). In chaetiger 24 base of notopodial ligules start to elongate and broader, increased progressively along following chaetigers, reaching and maintaining maximum size along chaetigers 70 to 98, then progressively reduced along chaetigers 99 to 106 ( Fig. 5 D–I). Dorsal cirri basally attached to dorsal ligule throughout, longer than dorsal ligule throughout ( Fig. 5 D–I). Notopodial ventral ligule conical on anterior chaetigers, becoming digitiform along chaetigers 24 to 104, conical on last two chaetigers ( Fig. 5 D–I). Neuropodium with prominent inferior and superior lobes on all chaetigers with exception of last two chaetigers ( Fig. 5 D–I). Neuropodial postchaetal lobe present throughout. Neuropodial ventral ligule conical on anterior chaetigers, digitiform along chaetigers 24 to last chaetiger; ventral cirri mid-ventrally attached to ventral edge of parapodia, longer than ventral ligule throughout ( Fig. 5 D–I).

Notochaetae present from chaetiger 3 to posterior chaetigers, homogomph spinigers ( Fig. 6A ). Neurochaetae, dorsal fascicle: homogomph and heterogomph spinigers ( Fig. 6B, C ), and heterogomph falcigers with short serrated terminal blade ( Fig. 6D ). Neurochaetae, ventral fascicle: heterogomph spinigers ( Fig. 6E ), and heterogomph falcigers with short serrated terminal blade ( Fig. 6F ). Pygidium round, one pair of filamentous anal cirri attached ventrally, extending about 7 chaetigers.

Etymology. The name is derived from the name of the fishing port, Hsinchu, where the worm was collected.

Type locality. Hsinchu City, Taiwan .

Distribution. Only known from the type locality.

Remarks. Neanthes hsinchuensis n. sp. belongs in the group of 14 species without paragnaths on Area V of the pharynx, from a total of 29 species reported from East Asia and Southeast Asia ( Hsueh 2019). The species in this group are N. bongcoi Pillai, 1965 , N. donggungensis Hsueh, 2019 , N. flava Wu, Sun & Yang, 1981 , N. glandicincta ( Southern, 1921) , N. kaomeiensis Hsueh, 2019 , N. maculata Wu, Sun & Yang, 1981 , N. nanhaiensis Wu, Sun & Yang, 1981 , N. pachychaeta ( Fauvel, 1918) , N. philippinensis de León-González & Salazar-Vallejo, 2003 , N. sakhalinensis ( Okuda, 1935) , N. suluensis Kirkegaard, 1995 , N. trifasciata ( Ehlers, 1901) , N. trifasciata vandersandi ( Horst, 1924) , and N. wilsonchani Lee & Glasby, 2015 ( Ehlers 1901: 107, pl. 12, fig. 3, 4; Fauvel 1918: 507, fig. 3e – h; Southern 1921: 590 – 592, text-fig. 5a – e, pl. XXIII, fig. 9K – L; Horst 1924: 155; Okuda 1935: 56 – 57, fig. 3c – e; Pillai 1965: 142 – 144, fig. 12F, H – G; Wu et al. 1981: 134, 140 – 142, 144 – 145, figs 83F – J, 86G – J, 89H – G; Kirkegaard 1995: 33 – 34, fig. 19c; de León-González & Salazar-Vallejo 2003: 368 – 370, fig. 2E – J; Glasby et al. 2011: 362 – 369, figs 1C – D, 8D; Lee & Glasby 2015: 89; Hsueh 2019: 177 – 178, 181 – 182,, figs 4B – E, 8B – D; Fig. 6B – F ; Table 2 ). Of these 14 species, N. hsinchuensis n. sp. resembles N. maculata , N. suluensis , N. trifasciata , and N. trifasciata vandersandi because they do not have notopodial prechaetal lobes ( Table 2 ). However, N. hsinchuensis n. sp. can be readily distinguished from these four species by the paragnaths pattern on the pharynx and types of neuropodial chaetae. Neanthes hsinchuensis n. sp. has greater number of conical paragnaths on Area III of the pharynx than those present in the other four species (29 vs. 6 – 18, 0, 8 and 15, respectively) ( Table 2 ). Further, the number of paragnaths on Area VII/VIII of the pharynx in N. hsinchuensis n. sp. is 12, whereas in the four other species is 46, 1, 2 – 7 and 3 – 6, respectively ( Table 2 ). Moreover, N. hsinchuensis n. sp. has three types of chaetae (homogomph and heterogomph spinigers, and heterogomph falcigers) on upper neuropodial fascicle, comparing only one (homogomph spinigers) or two types (homogomph spinigers and heterogomph falcigers) of chaetae in that of the four species ( Table 2 ). Neanthes hsinchuensis n. sp. can be further distinguished from N. suluensis , N. trifasciata , and N. trifasciata vandersandi by having short bladed heterogomph falcigers, whereas the three other species have either long or both short and long bladed heterogomph falcigers ( Table 2 ). Neanthes maculata has short bladed heterogomph falcigers on ventral fascicle of the neuropodia as in N. hsinchuensis n. sp. ( Table 2 ). However, blades of heterogomph falcigers in N. maculata have serrations on the entire length of the blade, but blades of heterogomph falcigers in N. hsinchuensis n. sp. have serrations only basally ( Wu et al. 1981: 136, fig. 83H–J; Fig. 6E, F ). The most prominent morphological feature separating N. hsinchuensis n. sp. from the above-mentioned fourteen congeners is the different elongation of the notopodial dorsal ligule on different body segments of N. hsinchuensis n. sp., which is not seen in any of these fourteen congeners ( Ehlers 1901: 107, pl. 12, figs 1, 2, 5; Fauvel 1918: 507, fig. b – d; Southern 1921: 590 – 592, pl. XXIII, fig. 9E – H; Horst 1924: 155; Okuda 1935: 55 – 56, figs 2a – c, 3a; Pillai 1965: 142 – 144, fig. 12D, E, J; Wu et al. 1981: 134, 140 – 142, 144 – 145, figs 83C – E, 86C – F, 89C – F; Kirkegaard 1995: 33 – 34, fig. 19b; de León-González & Salazar-Vallejo 2003: 368 – 370, fig. 2B – D; Glasby et al. 2011: 362 – 369, fig. 1B – D; Lee & Glasby 2015: 89, fig. 11A – D; Hsueh 2019: 177 – 178, 181 – 182,, figs 3D – G; 7D – G).

The description of N. hsinchuensis n. sp. is based on one specimen and therefore unable to provide information on variations of morphological characters (i.e., length ratio of peristomium/chaetiger 1, numbers of lateral teeth on jaws, numbers of paragnaths on pharyngeal rings), which have been often observed within a population ( Bakken 2006; Glasby & Hsieh 2006; Hsueh 2019).

Figures

FIG. 5. Neanthes hsinchuensis n. sp.; holotype (NMNS 8064-001): A, whole animal, dorsal view; B, anterior end, dorsal view, arrow indicates the apodous segment; C, paragnaths of the pharynx, ventral view (arrows point to Area VI paragnaths); D, chaetiger 10, right parapodium, anterior view; E, chaetiger 17, right parapodium, anterior view; F, chaetiger 24, right parapodium, anterior view; G, chaetiger 31, right parapodium, anterior view; H, right parapodium, anterior view, chaetiger 70; I, chaetiger 105, right parapodium, anterior view. (Abbreviations: DC, dorsal cirrus; NeIL, neuropodial inferior lobe; NePL, neuropodial postchaetal lobe; NeVL, neuropodial ventral ligule; NoDL, notopodial dorsal ligule; NoVL, notopodial ventral ligule; NeSL, neuropodial superior lobe; VC, ventral cirrus). Scale bars: A, 10.0 mm; B–I, 1.0 mm.

FIG. 6. Neanthes hsinchuensis n. sp.; holotype (NMNS 8064-001): A, chaetiger 59, notochaeta, homogomph spiniger; B, chaetiger 96, neurochaeta, dorsal fascicle, homogomph spiniger; C, same, neurochaeta, dorsal fascicle, heterogomph spiniger; D, same, neurochaeta, dorsal fascicle, short heterogomph falciger; E, same, neurochaeta, ventral fascicle, heterogomph spiniger; F, same, neurochaeta, ventral fascicle, short heterogomph falciger. Scale bars: A–C, E, 0.5 mm; D, F, 0.1 mm.

Tables

TABLE 2. Key morphological characters of Neanthes species have been reported from East and Southeast Asia and the present study, which have no paragnath teeth on Area V of the pharynx. Abbreviations: DFN = neurochaetae of dorsal fascicle; HoS = homogomph spinigers; HeF = heterogomph falcigers; NPL = notopodial prechaetal lobe; SeS = sesquigomph spinigers; SeF = sesquigomph falcigers; THeF = blade types of heterogomph falcigers; VFN = neurochaetae of ventral fascicle; n/a = not available.

Species\ Categories				Paragnaths				NPL	DFN	VFN	THeF
	I	II	III	IV	V	VI	VII/VIII
N. bongcoi Pillai, 1965	1	6–8	5	4–5	0	3–4	12	present	HoS, HeF	HeS, HeF	long
N. donggungensis Hsueh, 2019	2	8–11	12–15	15–17	0	7–13	76–91	present	HoS, HeF	HeS, HeF	medium
N. flava Wu, Sun & Yang, 1981	1	10–12	1	9–10	0	6–7	40–50	present	HoS, HeF	HeS, HeF	long
N. glandicincta ( Southern, 1921)	0–17	7–21	30–63	7–20	0	0–1	0–8	present	HoS	SeS, SeF	long
N. hsinchuensis n. sp.	2	12–14	29	24–26	0	3–4	12	absent	HoS, HeS, HeF	HeS, HeF	short
N. kaomeiensis Hsueh, 2019	6–7	8–12	30–36	8–12	0	1	0	present	HoS	SeS, SeF	long
N. maculata Wu, Sun & Yang, 1981	1–3	6–12	6–18	10–18	0–1	2–5	46	absent	HoS, HeF	HeS, HeS, HeF	short
N. nanhaiensis Wu, Sun & Yang, 1981	0	5–8	3–5	9–11	0	0	1–3/0	present	HoS, HeF	HoS, HeF	medium/ long
N. pachychaeta ( Fauvel, 1918)	1–4	4–13	1–8	2–11	0–2	0–8	0–8	present	HoS, HeF	HeS, HeF	medium
N. philippinensis de León- González & Salazar-Vallejo, 2003	3	9	5	9	0	3	5	present	HoS, HeF	HeS, HeF	short/ medium
N. sakhalinensis ( Okuda, 1935)	2	12–14	28	19–21	0	4–5	8	present	HoS, HeF	HoS, HeF	long
N. suluensis Kirkegaard, 1995	0	0	0	0	0	0	1	absent	HoS	HoS, HoF	long
N. trifasciata ( Ehlers, 1901)	0	11	8	n/a	0–1	3–6	2–7	absent	HoS, HeF	HoS, HeF	short/ long
N. trifasciata vandersandi ( Horst, 1924)	0	2–15	15	n/a	0	n/a	3–6	absent	HoS, HeF	HeF	long
N. wilsonchani Lee & Glasby, 2015	0–4	4–9	11–18	1–9	0	0–1	0–5	present	SeS	SeS, SeF	n/a