Lepidastheniella nishii, Barnich & Fiege, 2004

Barnich, R & Fiege, D, 2004, Revision of the genus Lepidastheniella Monro, 1924 (Polychaeta: Polynoidae: Lepidastheniinae) with notes on the subfamily Lepidastheniinae and the description of a new species, Journal of Natural History 38, pp. 863-876 : 872-874

Lepidastheniella nishii sp. nov.

(figure 3A–I)

Type material. Lepidastheniella nishii , holotype: af (63 segments; only few last segments missing), CMNH ZW01400 , Shimoda, St. 43, 34 ° 37.339 ∞ N, 138 ° 58.183 ∞ E, 13 July 2000, dredge, 93–109 m, leg. Rei Ueshima.

Additional material. Three spms (2 mf, 3 pf), CMNH ZW01401 , Shimoda, St. 43, 34 ° 37.339 ∞ N, 138 ° 58.183 ∞ E, 13 July 2000, dredge, 93–109 m, leg. Rei Ueshima. (Although all specimen fragments studied herein were found at the same station, it is impossible to decide whether one of them belongs to the holotype.)

Description (based on holotype, except for characters described for last few segments). Dorsum without distinct pigmentation; antennae, tentacular cirri and dorsal cirri pigmented, except for distalmost part. Anterior end (figure 3A): prostomium without cephalic peaks; median antenna with ceratophore in anterior notch, style smooth, abruptly tapering sub-distally; lateral antennae inserted terminally, with distinct ceratophores, styles smooth, abruptly tapering sub-distally; anterior pair of eyes dorsolaterally on widest part of prostomium, posterior pair dorsally near posterior margin (prostomium of holotype slightly damaged at right side); palps smooth, tapering (broken on holotype, but one separate in vial); facial tubercle absent. Pharynx extended, with two pairs of jaws and nine pairs of border papillae (not figured). Tentaculophores (segment 1) inserted laterally to prostomium, without chaetae, with a pair of dorsal and ventral tentacular cirri with styles smooth, abruptly tapering sub-distally. Second segment with first pair of elytra, sub-biramous parapodia, and long, ventral buccal cirri; few, slender, spinous notochaetae present; neurochaetae distally with distinct rows of spines and unidentate, elongate, pointed tips.

Numerous pairs of elytra, inserted on segments 2, 4, 5, alternating to end of body, last three to four segments cirrigerous (cf. additional material); elytra covering dorsum all over body; elytral margin smooth; elytral surface mostly smooth, except for a band of conical microtubercles present near margin in anterior half of elytron (figure 3B, C). Styles of dorsal cirri smooth, abruptly tapering sub-distally in anterior segments, tapering gradually in more posterior ones; anteriormost reaching well beyond tips of neurochaetae, more posterior ones getting shorter (figure 3A); styles of ventral cirri smooth, tapering, shorter than neuropodia (figure 3D).

Parapodia sub-biramous, smooth; notopodia reduced; neuropodia truncate, notched dorsally and ventrally, with elongate distally rounded lobes; tips of noto- and neuro-acicula not penetrating epidermis (figure 3D). Without or with few, slender notochaetae (up to three), short ones with blunt tips, longer ones with elongate, pointed tips (figure 3E, F). Neurochaetae more numerous (up to 20), stout, falcate, with numerous rows of spines, without crest near tip, tips mostly bidentate with stout secondary tooth (sometimes abraded), some upper and lower unidentate with blunt tips, in anterior segments uppermost occasionally with elongate, pointed tips (figure 3G–I).

Nephridial papillae rather indistinct, beginning at segment 8. Holotype female with eggs visible in parapodia from segment 14.

Etymology. The species is named in honour of Dr Eijiroh Nishi, polychaetologist at Yokohama National University, Japan, who made it possible for us to study an interesting collection of Japanese scale worms.

Remarks. The new species Lepidastheniella nishii is close to L. comma ; distinguishing characters of the former are bi- and unidentate neurochaetae and parapodia without or with up to three notochaetae (figure 3E–I), while the latter shows exclusively unidentate neurochaetae and a rather high number of notochaetae (up to 20) (figure 1F–J).

Measurements. Holotype of Lepidastheniella nishii : L 46 mm, W 9 mm for 63 segments (anterior fragment with only last few segments missing).

Distribution. Off Shimoda, Honshú, Japan.

Habitat. 100 m.