Eunereis shichengensis, Hsueh, 2018

Hsueh, Pan-Wen, 2018, First records of Composetia, Eunereis and Nectoneanthes (Annelida: Nereididae) from Taiwan, with descriptions of two new species, Zootaxa 4531 (2), pp. 211-224 : 218-219

Eunereis shichengensis n. sp.

Figs 3 A–C, 4A–D, 5A–E

Material examined. Holotype ( NMNS 7898-007 ), Shicheng (24°58´46˝N 121°57´01˝E), in oyster clusters on cement wall of the Shicheng harbour, Ilan County, 21 July 2016.

Diagnosis. Body nereidid form, longest posterior tentacular cirri reaching chaetiger 4. Jaws dark brownish, each with 5 to 6 lateral teeth; maxillary ring of pharynx without paragnaths, oral ring paragnaths as: Area V=3 cones, in triangle; Area VI=1, 1 shield-shaped bars; Areas VII/VIII=33 cones, in 2 to 3 rows. Notopodial prechaetal lobes present throughout. Notochaetae: homogomph spinigers. Neurochaetae, dorsal fascicle: homogomph spinigers and short heterogomph falcigers. Neurochaetae, ventral neurochaetae: heterogomph spinigers and short heterogomph falcigers.

Description. Holotype, ovigerous female, complete, body length 55.1 mm with 78 chaetigers, maximum width 3.3 mm at chaetiger 6, excluding parapodia; dorsal and lateral body surfaces dark brown pigmented, light brown to beige on parapodia and ventral surface in alcohol ( Fig. 4A ).

Prostomium anterior margin entire, one pair of antennae, one pair of biarticulated palps, with conical palpostyles; four pairs of tentacular cirri with distinct cirrophores, longest tentacular cirri reaching chaetiger 4 ( Fig. 4B ). Two pairs of eyes, anterior pairs and posterior pairs similar in size, trapezoidal arranged. Apodous segment present, about 1.3 times as long as chaetiger 1. Jaws dark brownish, with 5–6 lateral teeth; pharyngeal maxillary ring without paragnaths, oral ring paragnaths as: Area V=3 cones, in triangle; Area VI=1, 1 shield-shaped bars ( Fig. 4C ); Areas VII/VIII=33 cones, in 2 to 3 rows.

First 2 chaetigers with neuroaciculae only, thereafter noto-aciculae also present. Notopodial dorsal ligule conical, base slightly dorsal expanded on anterior chaetigers ( Fig. 5A, B ); triangular, shorter and laterally compressed on middle chaetigers; triangular with base significantly elongate and laterally expanded from chaetiger 44 to chaetiger 75 ( Fig. 5C, D ); drastically reduced to small size but remaining laterally expanded in next five chaetigers prior to pygidium; basal dorsal edge of dorsal ligule sporadically filled with glands on anterior to middle chaetigers, entirely filled with gland on posterior chaetigers ( Fig. 5C, D ). Dorsal cirri attached basally to dorsal ligule, longer than dorsal ligule on anterior chaetigers ( Fig. 5A, B ), becoming subequal to dorsal ligule on middle chaetigers, shorter than dorsal ligule on posterior chaetigers. Notopodial ventral ligule conical on anterior chaetigers, triangular and blunt tipped on posterior chaetigers. Notopodial prechaetal lobes present throughout ( Fig. 5A, C ). Neuropodia with prominent inferior lobe on anterior chaetigers, blunt tipped. Superior lobe present on anterior chaetigers, digitiform with a blunt tip ( Fig. 5A, B ). Neuropodial postchaetal lobe present on anterior chaetigers, wide triangular with a blunt tip ( Fig. 5B ). Neuropodia without inferior, postchaetal or superior lobe on posterior chaetigers, acicular lobes rounded distally ( Figs 5 C–E). Neuropodial ventral ligule conical throughout; ventral cirri attached to middle of neuropodial ventral surface, shorter than ventral ligule ( Fig. 5 A–D).

Notochaetae present from chaetiger 3 to posterior chaetigers, homogomph spinigers ( Fig. 6A ). Neurochaetae, dorsal fascicle: homogomph spinigers ( Fig. 6B ) and short heterogomph falcigers present ( Fig. 6C ). Neurochaetae, ventral fascicle: heterogomph spinigers and short heterogomph falcigers present, terminal blade with serrations ( Fig. 6D, E ). Pygidium rounded with one pair of non-articulate ventral cirri extending back about 5 chaetigers ( Fig. 4A ).

Etymology. The species name is derived from the name of the village, Shicheng where the worm was collected.

Type locality. Shicheng Harbour , Ilan County, Taiwan .

Distribution. Only known from the type locality.

Remarks. León-González & Solís-Weiss (2000) divided the known species of the genus into two groups on the basis of the absence/presence of notopodial homogomph falcigers. The group with notopodial homogomph falcigers includes E. eugeniae León-González and Solís-Weiss, 2000 , E. longipes ( Hartman, 1936) , E. longissima , E. marri and E. wailesi ( Berkeley & Berkeley, 1954) , whereas the group without notopodial homogomph falcigers includes E. caeca Hartman, 1960 , E. elittoralis , E. paitillae Fauchald, 1977 and E. patagonica ( McIntosh, 1885) ( McIntosh 1885; Hartman 1960; Eliason 1962; Fauchald 1977). Eunereis shichengensis n. sp. has only notopodial homogomph spinigers ( Fig. 6A ) and can be included in the latter group. Of the 5 species without notopodial homogomph falcigers, only E. paitillae has bar-shaped paragnaths on pharyngeal oral ring (i.e., one each on Area VI and three smooth bars on Area VII) ( Fauchald 1977: 25, fig. 5a, e). Eunereis shichengensis n. sp., however, differs from E. paitillae by having one shield-shaped bar on Area VI and 33 conical paragnaths on Area VII/VIII of the pharynx, respectively. Moreover, E. shichengensis n. sp. has homogomph spinigers and heterogomph falcigers in dorsal fascicle of neuropodia, but that of E. paitillae has heterogomph spinigers and heterogomph falcigers ( Fauchald 1977: 25; Fig. 6B, D ). It is worth mentioning that the presence of the shield-shaped bars on Area VI of the pharynx in the present species is also observed for the group of Perinereis species with a single Area VI paragnaths and several Pseudonereis species ( Bakken 2007; Bakken et al. 2009, 2018; Conde-Vela 2018).

Figures

FIGURE 3. Composetia budaiensis n. sp.; A–C, F–H, paratype (NMNS 7898-004); D, E, paratype (NMNS 7898-002). A, notochaetae, homogomph spinigers, chaetiger 72; B, neuropodial homogomph spinigers, dorsal fascicle, chaetiger 76; C, neuropodial sesquigomph spinigers, dorsal fascicle, chaetiger 76; D, neuropodial homogomph spinigers, ventral fascicle, chaetiger 5; E, neuropodial sesquigomph falciger, ventral fascicle, chaetiger 5; F, neuropodial homogomph spinigers, ventral fascicle, chaetiger 72; G, neuropodial sesquigomph falciger, ventral fascicle, chaetiger 72; H, neuropodial sesquigomph falciger, ventral fascicle, chaetiger 76. Scale: A–H, 0.01 mm.

FIGURE 4. Eunereis shichengensis n. sp.; holotype (NMNS 7898-007). A, whole animal; B, anterior body, lateral view; C, pharynx. Roman numeric numbers: Areas of the pharynx. Scale: A, 5.0 mm; B, 0.5 mm; C, 1.0 mm.

FIGURE 5. Eunereis shichengensis n. sp.; holotype (NMNS 7898-007). A, left chaetiger 6, anterior view; B, left chaetiger 6, posterior view; C, left chaetiger 53, anterior view; D, chaetiger 53, posterior view; E, close-up of neuropodia, left chaetiger 53, anterior view. Abbreviations: DC, dorsal cirrus; Gla, gland; IL, inferior lobe; NeAL, Neuropodial acicular lobe; NePL, neuropodial postchaetal lobe; NeVL, neuropodial ventral ligule; NoDL, notopodial dorsal ligule; NoVL, notopodial ventral ligule; SL, superior lobe; VC, ventral cirrus. Scale: A–D, 0.5 mm; E, 0.1 mm.

FIGURE 6. Eunereis shichengensis n. sp.; holotype (NMNS 7898-007). A, notopodial homogomph spinigers, chaetiger 63; B, neuropodial homogomph spinigers, dorsal fascicle, chaetiger 63; C, neuropodial heterogomph spinigers, ventral fascicle, chaetiger 63; D, neuropodial heterogomph falciger, dorsal fascicle, chaetiger 63; E, neuropodial heterogomph falciger, ventral fascicle, chaetiger 63. Scale: A–E, 0.01 mm.