Therochaeta sp.

Salazar-Vallejo, Sergio I., 2013, Revision of Therochaeta Chamberlin, 1919 (Polychaeta: Flabelligeridae), Zoosystema 35 (2), pp. 227-263 : 244

Therochaeta sp. from Xcacel

MATERIAL EXAMINED. — Caribbean Sea. One specimen (ECOSUR unnumb.), Quintana Roo, Xcacel , northern reef lagoon (20°20’28”N, 87°20’35”W), 1.5 m, coral rocks, 17.IV.1996, L.F. Carrera & SISV coll.

DISTRIBUTION. — Only known from the collection site.

DESCRIPTION

Complete specimen, wider anteriorly and medially, tapered posteriorly. Body cross-section oval; 3 mm long, 1 mm wide, cephalic cage 2 mm long, 22 chaetigers. Body surface with abundant long papillae and large sediment particles adherent,especially in anterior chaetigers.Body papillae cirriform, markedly capitate, not forming large sediment tubercles.

Anterior end exposed, appendages lost, cephalic hood broken. Cephalic cage chaetae 2/3 as long as body length, or twice as long as body width. Cephalic cage made by chaetigers 1-2, but chaetiger 2 with smaller, fewer chaetae; chaetiger 1 with six notochaetae and four neurochaetae, chaetiger 2 with two notochaetae and two neurochaetae per side.

Anterior dorsal margin of first chaetiger with flat lobe with three distal papillae. All chaetigers with very long notopodial papillae, especially in chaetiger 1; the rest about as long as 1/5-1/6 notochaetal length. Chaetiger 2 markedly longer than chaetiger 3, slightly constricted on its posterior margin. Chaetal transition from cephalic cage to body chaetae abrupt; pseudocompound neurohooks from chaetiger 3. Gonopodial lobes not seen.

Parapodia poorly developed, chaetae emerge from body wall. Notopodia with papillae longer than neuropodia. Noto- and neuropodia close to each other. Median notochaetae arranged in short transverse series. All notochaetae multiarticulated capillaries, articles short basally, medium-sized medially, longer distally, longest chaetae as long as half body width. Neuropodia ventrolateral. Neurochaetae multiarticulated capillaries in chaetigers 1-2, pseudocompound hooks, two per ramus, in chaetigers 3-8, and anchylosed neurohooks in chaetigers 9-21, two in most chaetigers, but a single one in chaetigers 20-21.

Posterior end tapered to a blunt cone; anus terminal, without anal cirri.

REMARKS

This juvenile specimen was collected in shallow-water mixed bottoms. It differs from T. collarifera and from T. fauchaldi n. sp.; from the former because it lacks sediment tubercles, although both have three transverse rows of capitate papillae, and from the latter, because it has large sediment particles. It also differs from other Caribbean juveniles reported above in several features. Both may represent undescribed, shallow water species, but more and better preserved materials are needed before formally naming them.