Therochaeta sp.

Salazar-Vallejo, Sergio I., 2013, Revision of Therochaeta Chamberlin, 1919 (Polychaeta: Flabelligeridae), Zoosystema 35 (2), pp. 227-263 : 242-244

Therochaeta sp. Solarte

MATERIAL EXAMINED. — Caribbean Sea. One specimen ( LACM-AHF LH03-609), anterior fragment, Panama, Bocas del Toro Archipelago, Bahia Almirante , Isla Solarte , south side, entrance (9.3°N, 82.207°W), SCUBA, 7.6 m, 6.VIII.2003 .

DISTRIBUTION. — Only known from the collection site.

DESCRIPTION

Anterior fragment; anteriorly truncate, tapered posteriorly. Body cross-section oval; 1.4 mm long, 0.4 mm wide, cephalic cage 1.4 mm long, 10 chaetigers. Body surface rugose, with few long papillae and fine sediment particles adherent throughout its surface. Body papillae cirriform, slightly capitate, with fine sediment particles, longer in notopodial bases and arranged as four longitudinal series.

Anterior end not observed. Cephalic cage chaetae three times longer than body width, made by chaetiger 1, displaced dorsally. Chaetigers 2-3 with long chaetae but not as long as those present in chaetiger 1. Chaetiger 1 with four chaetae per bundle.

Anterior dorsal margin of first chaetiger papillated. All chaetigers with very long notopodial papillae, especially in chaetiger 1; the rest about as long as 1/3 notochaetal length. Chaetiger 2 slightly longer than chaetiger 3 but without constriction on its posterior margin. Chaetal transition from cephalic cage to body chaetae abrupt; pseudocompound neurohooks from chaetiger 2. Gonopodial lobes not seen.

Parapodia poorly developed, chaetae emerging from the 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 long, longest chaetae as long as half body width.Neuropodia ventrolateral.Neurochaetae multiarticulated capillaries in chaetiger 1, and one multiarticulate chaetae in chaetiger 2, two pseudocompound hooks in chaetiger 2, three pseudocompound neurohooks in chaetigers 3-4, two neurohooks in chaetiger 5 and three ones in the chaetiger 6. Pseudocompound hooks from chaetiger 2 with handle multiarticulated, whereas the following ones have a smooth, anchylosed handle with blade progressively reduced. Anchylosed neurohooks from chaetiger 7, three in chaetigers 7-8 and two in chaetigers 9-10.

Posterior end unknown.

REMARKS

This juvenile specimen might belong to T. collarifera or to T.fauchaldi n. sp. although the Grand Caribbean species is the former. However, it cannot be assigned to either because it lacks the sediment tubercles found in the former and the abundant papillae found in the latter.It may belong in T.collarifera since there are few papillae and the sediment tubercles may start from a gradual accumulation of sediment grains, and then these tubercles continue their growth over some body papillae.On the other hand, despite the fact this specimen lacks its posterior region it may help understand some ontogenetic changes in neurochaetal patterns, because, they start earlier than in larger specimens.