Eunice reticulata, 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 : 161-163

Eunice reticulata sp. nov.

Fig. 6

Material examined. Taiwan: Holotype ( NMNS 6695), Jihuei (23°06´53˝N, 121°24´11˝E), Taitung County, intertidal algal and coral mixed reefs, August 22, 2010; paratypes: two specimens ( NMNS 2572-113, 113-1), Wunzihkeng (25°02´31˝N, 121°55´47˝E), New Taipei, intertidal hard-bottom, March 12, 1989; one specimen ( NMNS 2572-111), Dawen (21°57´23˝N, 120°45´17˝E), Pingtung County, subtidal hard-bottom, 4–6 m deep, August 14, 1996; one specimen ( NMNS 2572-118), Houbihu Fish Port (21°57´26˝N, 120°45´32˝E), Pingtung County, subtidal hard-bottom, 4 m deep, June 25, 1989.

Description. Holotype, complete specimen, sex unknown, 255 mm long with 255 chaetigers; maximum width about 6.0 mm at chaetiger 18; length through chaetiger 10 about 17.5 mm. Anterior body slightly compressed dorsoventrally, dorsum reticulated with iridescence on both sides ( Fig. 6 A–B), posterior body cylindrical without reticulation, becoming pale, tapering to the end. Paired anal cirri present, short, ovate, without articulations ( Fig. 6 C).

Prostomium distinctly shorter than peristomium, equal in width and about 1/2 as deep as peristomium; prostomial lobes frontally rounded, dorsally flattenned, median sulcus deep ( Fig. 6 A–B). Eyes present, situated posteriorly to base of palps, ovate and purple red. Palps and antennae arranged in semicircle, similar in thickness, median antenna isolated by gap; palpophore and ceratophore bases short cylindrical, with indistinct ring; palpostyles and ceratostyles digitiform; A-I, A-II and A-III with 7 indistinct cylindrical articulations, left palps 6 articulations and right 4 articulations; A-II reaching chaetiger 1, A-II to posterior peristomium, palps to middle of anterior peristomial ring. Peristomium lower lip distinctly muscular; separation between rings distinct all around, anterior peristomium about 2/3 of total peristomial length, peristomial cirri tapering, without articulations, brown band present subdistally in larger specimen ( Fig. 6 O).

Maxillary formula: 1+1, 4–5+4–5, 6–8+0, 3–4+6–7, 1+1; MxIII located at front end part of distal arc with left MxIV ( Fig. 6 D); mandibles flat ( Fig. 6 E).

Branchiae present, pectinate, distinctly longer than dorsal cirri, not reduced in mid-body region ( Fig. 6 F–G). Branchiae present from chaetiger 5 to chaetiger 75, representing about 23 % of chaetigers branchiate; anterior and last 10 pairs with single filament; most branchiae between chaetiger 12 to chaetiger 45 with 15 to 18 filaments, chaetiger 31 with maximum 21 filaments; branchial filaments tapering, shorter than dorsal cirri, similar in thickness to dorsal cirri.

Anterior neuropodial acicular lobes rounded, acicular lobes transverse folds at middle segments and triangle at posterior segments ( Fig. 6 F–H); aciculae emerging above midline; prechaetal lobes low, transverse folds, postchaetal lobes projected as free lobes at anterior segments and becoming truncate at posterior segments. First seven ventral cirri bases without inflation, digitiform; median ventral cirri thick, swollen laterally, bases slightly inflated; posterior ventral cirri short, digitiform, without inflation. Dorsal cirri tapering, without articulations, brown bands present subdistally at anterior body in large specimen ( Fig. 6 O).

Limbate chaetae elongate, longer than all other chaetae, marginally serrated. Pectinate chaetae furled, flaring, marginal teeth heterodont, 18 inner teeth ( Fig. 6 I). Shafts of compound falcigers distally inflated, beak-like, marginally serrated; appendages tapering, bidentate; proximal tooth triangle, perpendicular to axis of appendage, distinctly smaller than distal tooth at anterior segments, about equal to distal tooth at posterior segments; distal tooth scimitar-shaped, both proximal and distal tooth directed laterally ( Fig. 6 J); guards marginally serrated, without mucros; asymmetrical on anterior segments, distally blunt; symmetrical on posterior segments, distally blunt; pseudo-compound falcigers and compound spinigers absent. Aciculae dark brown, distally blunt, crosssections round; chaetiger 1 to chaetiger 45 with paired aciculae, thereafter single per chaetiger; separation between core and sheath distinct in both aciculae and subacicular hooks ( Fig. 6 K). Subacicular hooks dark brown, bidentate, present from chaetiger 30 to last chaetiger, most with one per chaetiger, some chaetigers with two hooks; shafts of hooks straight, subdistally tapering; proximal tooth triangle, distally blunt, directed laterally, distinctly larger than distal tooth; distal tooth triangle, directed laterally; guards ginkgo leaf-like, covering only proximal tooth ( Fig. 6 L).

Etymology. The name is derived from the reticulate pattern on dorsum of the worm.

Type locality. Jihuei, Taitung County, Taiwan.

Habitat. Intertidal and subtidal areas of algal and coral mixed reefs.

Distribution. Known only from Taiwan, occurs on northeastern, eastern and southern coasts of Taiwan.

Remarks. This new species belongs to the B-1 group (sensu Fauchald 1970). The presence of articulations on the prostomial appendages and lack of articulations on either peristomial or parapodia dorsal cirri, aligns the new species to one species in the group, namely Eunice rosaurae Monro, 1939 ( Miura 1987: 1–4, Figs. 1–2; Fauchald 1992: 350, Table 25; Carrera-Parra & Salazar-Vallejo 1998: 162–163, Fig. 5 H–M). However, several characters can be used to separate the former species from the new species. Eunice rosaurae is different from Eunice reticulata sp. nov., by having: 1) moniliform prostomial appendages, 2) single filament branchiae, 3) flat and tapering pectinate chaetae with 10 inner teeth, 4) appendages of compound falcigers with relative small bidentate head, and 5) tridentate or distally fused bidentate subacicular hooks ( Fauchald 1992: 287, Fig. 961–p), in comparison to: 1) cylindrical articulated prostomial appendages, 2) pectinate branchiae, 3) furled and flaring pectinate chaetae with 18 inner teeth, 4) appendages of compound falcigers with relative large bidentate head, and 5) bidentate subacicular hooks of the new species ( Fig. 6 A–L).

The reticulate pattern and iridescence on the dorsum of the anterior body of Eunice reticulata sp. nov., as well as the brown bands on the prostomial appendages and parapodia dorsal cirri, vary with size. Smaller specimens often have smooth dorsum throughout the body. The reticulate pattern and iridescence on anterior dorsum gradually appear on medium sized specimens and become obvious on large specimens; the same type of ontogenetic change occurs also on the colour bands on prostomial appendages and dorsal cirri ( Fig. 6 M–O).

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.

FIGURE 6. Eunice reticulata sp. nov. A, dorsal view of anterior end; B, lateral view of anterior end; C, dorsal view of posterior end with two anal cirri; D, maxillae; E, mandibles; F, left parapodium 11, anterior view; G, left parapodium 40, anterior view; H, right parapodium 104, anterior view. I, pectinate chaetae, left parapodium 40; J, compound falciger, right parapodium 70; K, acicula, left parapodium 40; L, subacicular hook, left parapodium 40; M – O, dorsal view, showing the ontogenetic changes of reticulate pattern on anterior dorsum of small, median and large specimens. A – L, O from holotype NMNS 6695; M from paratype NMNS 2572 - 111; N from paratype NMNS 2572 - 113. Scale bars: A – B, 5 mm; C – G, 1 mm; H, 0.5 mm; I – L, 0.05 mm; M – O, 2 mm.