Eunice jihueiensis, Hsueh, Pan-Wen & Li, Yan-Huei, 2014

Hsueh, Pan-Wen & Li, Yan-Huei, 2014, New species and new records of eunicids (Polychaeta, Eunicidae) from Taiwan, Zootaxa 3802 (2), pp. 151-172 : 159

Eunice jihueiensis sp. nov.

Fig. 5

Material examined. Taiwan: Holotype ( NMNS 6993), Jihuei (23°06´53˝N, 121°24´11˝E), Taitung County, intertidal algal and coral mixed reefs, October 14, 2007.

Description. Complete specimen, sex unknown, total body length 22.0 mm with 69 chaetigers; maximum width at chaetiger 1 about 0.8 mm; length through chaetiger 10 about 3.4 mm; chaetiger 10 width about 0.7 mm. Paired anal cirri present, elongate and tapering, without articulations ( Fig. 5 C). Body anterior rounded, compressed after chaetiger 6 to posterior region, tapering towards pygidium ( Fig. 5 A).

Prostomium distinctly shorter than peristomium, about as wide as peristomium, more than 1/2 as deep as peristomium, prostomial lobes anteriorly round, dorsally inflated separated by deep median sulcus. Eyes present, situated posteriorly to base of palps, rounded and black. Prostomial antennae and palps arranged in semicircle, almost evenly spaced, similar in thickness; palpophores and ceratophores bases ring-shaped, without articulations; palpostyles and ceratostyles tapering, wrinkled surface, without articulations. A-II reaching posterior margin of anterior ring of peristomium, A-I and III and palps to anterior margin of peristomium. Peristomial cirri short and tapering, about half-length of peristomium, surface wrinkled, without articulations ( Fig. 5 B).

Maxillary formula: 1+1, 4+5, 7+0, 4+9, 1+1; MxIII long, partially covered by MxII; mandibles flat.

Branchiae present, single filament, distinctly longer than dorsal cirri ( Fig. 5 D), first present on chaetiger 13 and absent by chaetiger 51, representing 57% of all chaetigers.

Acicular neuropodial lobes distally rounded; aciculae emerging above midline; prechaetal and postchaetal lobes truncate. First five ventral cirri short, digitiform, no inflation at base, chaetiger 6 to chaetiger 28 with inflated bases ovate, tips button-shaped, thereafter short, digitiform. Dorsal cirri short, surface wrinkled, without articulations ( Fig. 5 C).

Limbate chaetae slender, longest among all chaetae, marginally smooth ( Fig. 5 E); pectinate chaetae furled and flaring, with elongated marginal tooth on each side, 12 to 20 inner teeth ( Fig. 5 E–F). Shafts of compound falcigers slender, distally inflated, beak-like, marginally serrated, internal striations present ( Fig. 5 G); appendages tapering, bidentate; proximal tooth isosceles triangle, perpendicular to appendage; distal tooth about equal to proximal tooth at anterior segments, distinctly smaller than proximal tooth at posterior segments; guards distally symmetrically rounded, cutting edge finely serrated, without mucros ( Fig. 5 G); pseudo-compound falcigers and compound spinigers absent. Aciculae light yellow, distally blunt, cross-section round, single per chaetiger; separation of acicular cores and sheaths indistinct ( Fig. 5 H). Subacicular hooks light yellow, bidentate; present from chaetiger 12 (right body side) or chaetiger 14 (left body side) to last chaetiger, single per chaetiger; shafts of hooks straight, slightly inflated subdistally; proximal tooth acute angle triangle, nearly perpendicular to appendage, distinctly larger than distal tooth; guards large, distally truncate, covering distal head entirely, internal striations present ( Fig. 5 I).

Etymology. The name is derived from the name of village where the animal was collected.

Type locality. Jihuei, Taitung County, Taiwan.

Habitat. Intertidal areas of algal and coral mixed reefs.

Distribution. Known only from the type locality.

Remarks. The present species could be assigned to the A-3 group, with flavus-bidentate subacicular hooks and branchiae occurred between chaetiger 13 and chaetiger 51 which is less than 65% of the total chaetiger number (sensu Fauchald 1970, 1992). However, this group has never previously been reported for the genus Eunice ( Hartman 1944; Miura 1977, 1986, 1987; Fauchald 1970, 1986, 1992; Hanley 1986; Leon-Gonzalez 1988; Carrera- Parra & Salazar-Vallejo 1998, 2011; Hartmann-Schröder 1998; Hartmann-Schröder & Zibrowius 1998; Lu & Fauchald 1998, 2000; Zanol et al. 2000; Nogueira et al. 2001; Leon-Gonzalez et al. 2004; Ardila et al. 2005; Imajima 2006, 2007; Wu et al. 2013a, b). A possibility is that our specimen is too small to have developed adult features. However, it has peristomial cirri and therefore is not considered as a juvenile stage ( Nogueira et al. 2001; Zanol et al. 2014). Nogueira et al. (2001) examined Eunice (= Nicidion ) insularis ( Nogueira, Steiner & Amaral, 2001) , a eunicid with single or no branchiae, and noted that younger specimens of the species lack peristomial cirri, but are identical to the larger specimens with regards to all other features. Thus, at least for species with few branchial filaments, the branchial distribution pattern observed for this new species, we suggest is valid for all sized individuals of this species.

Figures

FIGURE 5. Eunice jihueiensis sp. nov. A, whole animal; B, dorsal view of anterior region; C, dorsal view of posterior end; D, left parapodium 14 to 16, dorsal view; E, limbate and pectinate chaetae, right parapodium 57; F, pectinate chaeta, right parapodium 46; G, compound falciger, right parapodium 52; H, acicula, right parapodium 58; I, subacicular hook, left parapodium 18. A – I from holotype NMNS- 6993. Scale bars: A, 5 mm; B – C, 1 mm; D, 0.5 mm; E – I, 0.05 mm.