Paratherochaeta coronata ( Ehlers, 1908 ), 2013

Salazar-Vallejo, Sergio I., 2013, Revision of Therochaeta Chamberlin, 1919 (Polychaeta: Flabelligeridae), Zoosystema 35 (2), pp. 227-263 : 252-253

Paratherochaeta coronata ( Ehlers, 1908) n. comb., restricted

( Fig. 10 )

Stylarioides coronatus Ehlers, 1908: 121-123 , pl. 16, figs 3-8 (partim); Hartwich 1993: 93.

Stylarioides coronatus – Caullery 1944: 35, fig. 26.

Therochaeta coronate – Fauchald 1972: 416 (n. comb.).

TYPE MATERIAL. — Western Indian Ocean. Lectotype of Stylarioides coronatus ( ZMB 6776 ), Deutsche Tiefsee-Expedition 1898-99, R/V Valdivia, Stat. 258 (02°58’N, 46°50’E), off Mogadishu ( Hamar ), Somalia, 1362 m, pteropod ooze .

DISTRIBUTION. — Western Indian Ocean and Java Sea, in deep water (1300-3300 m).

DESCRIPTION

Lectotype complete (ZMB 6776), slightly damaged, some portions of tunic eroded ( Fig. 10A ). Body medially swollen, tapered towards both body ends; 28 mm long, 2 mm wide, cephalic cage chaetae 16.5 mm long, 66 chaetigers. Chaetigers 1-7 with fine, cemented, sediment particles ( Fig. 10 A-C), following chaetigers without cemented particles, individual papillae with very fine sediment particles, not blocking their individual shape. Chaetigers 3-7 with triangular sediment tubercles, larger in chaetigers 3-4, gradually decreasing in following chaetigers ( Fig. 10B, C ).

Cephalic tube not exposed; anterior end details unknown.

Cephalic cage chaetae about as long as 4/7 body length or more than eight times longer than body width. Chaetigers 1-2 involved in cephalic cage; chaetiger 3 with long chaetae but not reaching anterior margin of chaetiger 1. Cephalic cage chaetae arranged into short series, four-five chaetae per bundle. Anterior dorsal margin of first chaetiger with a short rounded projection, margin papillated ( Fig. 10C ). Chaetigers 1-2 depressed, long papillae restricted to base of chaetal lobes. Chaetiger 1 very short, chaetiger 2 markedly longer, slightly constricted towards its posterior margin, chaetiger 3 shorter, slightly wider than chaetiger 2, shorter than chaetiger 1. Sand cemented anterior shield surrounding chaetigers 1-3, less well-defined in following chaetigers. Chaetal transition from cephalic cage to body chaetae abrupt; neurohooks start in chaetiger 7. Gonopodial lobes not seen.

Parapodia well-developed in chaetigers 1-3, flat lobes with elongate papillae and abundant chaetae; remaining parapodia poorly developed, chaetae emerge from body wall. Parapodia lateral, median neuropodia ventrolateral.Noto- and neuropodia short lobes, without long papillae; a single capitate interramal papillae.Noto- and neuropodia well separated.

Median notochaetae arranged in short transverse series; all notochaetae multiarticulated capillaries, all articles very long (five-six times longer than wide), progressively smaller towards tip; three-four per bundle, 1/6-1/7 as long as body width, longer in posterior chaetigers.Neurochaetae multiarticulated capillaries in chaetigers 1-3, chaetigers four-six with anchylosed thick neurospines, two per bundle ( Fig. 10E ); falcate neurohooks from chaetiger 7 ( Fig. 10F ), 4-6 per ramus in median and posterior chaetigers ( Fig. 10G ).

Posterior end tapered; pygidium rounded,colorless, with anus terminal, without anal cirri ( Fig. 10D ).

REMARKS

The type material of Stylarioides coronatus Ehlers, 1908 included two different species. One was illustrated as having its chaetiger 3 thicker than chaetigers 1-2, and provided with large papillae ( Ehlers 1908: pl. 16, figs 5-8); it was collected from shallow water (141 m). The other one was illustrated with a thinner chaetiger 3 and having smaller papillae ( Ehlers 1908: pl. 16, fig. 4); it was collected in deeper water (1302 m). Both syntypes were kept in Berlin ( Hartwich 1993: 93), but the shallow water form is dried-out; some specimens which are regarded as conspecific to one of them are described below as Paratherochaeta ehlersi n. sp. The remaining syntype, which was collected in deep water, is herein designated as a lectotype, in order to restrict the delineation of the species. This species does not belong in Therochaeta because it lacks pseudocompound chaetae in anterior chaetigers.

Paratherochaeta coronata n. comb. resembles P. antoni . They differ by the relative length of notochaetal median articles, since in P. coronata n. comb., they are five-six times longer than wide, whereas they are about three times longer than wide in P. antoni . These two species live in different water depths since P. coronata n. comb. was found in about 1300 m, whereas P. antoni lives in 110- 450 m.

Figures

FIG. 10. — Paratherochaeta coronata (Ehlers, 1908) n. comb., restricted,lectotype (ZMB 6776); A, lateral view; B, anterior end, lateral view;C, anterior end,dorsal view;D, posterior region,dorsal view;E, chaetiger 6, right parapodium,neurochaetae (insert:neurochaetae); F, chaetiger 7, right parapodium, neurochaetae (insert: neurochaetae enlarged); G, chaetiger 41, right parapodium, neurochaetae. Scale bars: A, 2 mm; B, 1 mm; C, 0.7 mm; D, 0.6 mm; E, G, 100 µm; F, 200 µm.