Revision of Therochaeta Chamberlin, 1919 (Polychaeta: Flabelligeridae) Author Salazar-Vallejo, Sergio I. El Colegio de la Frontera Sur CONACYT Chetumal, Quintana Roo (Mexico) savs551216@hotmail.com & ssalazar@ecosur.mx text Zoosystema 2013 2013-06-28 35 2 227 263 http://dx.doi.org/10.5252/z2013n2a7 journal article 163589 10.5252/z2013n2a7 240f297d-c280-4a16-a171-22f1bebdf852 1638-9387 5165233 Paratherochaeta n. gen. TYPE SPECIES. — Therochaeta antoni Kirkegaard, 1996 . GENDER. — Feminine. DISTRIBUTION. — Species of the genus thrive in tropical and subtropical regions, living in sediments from shallow waters ( 11 m ) to deep waters ( 3330 m ). DIAGNOSIS. — Body anteriorly swollen or tapered, often constricted between chaetigers 2 and 3. Chaetiger 1 short, chaetiger 2 long, with a transverse constriction on its posterior margin, chaetiger 3 elongated, dorsally elevated, with a narrow transverse band of long papillae. Anterior margin of chaetiger 1 with a dorsal lobe. Cephalic cage made by chaetigers 1-2. Tunic generally covered with sediment grains. Chaetigers 5-7 with multiarticulated neurospines, rarely capillaries; posterior neurochaetae anchylosed hooks or aristate, tapered multiarticulate capillaries. Eight or more cirriform branchiae, sessile on a low branchial plate. KEY TO SPECIES OF PARATHEROCHAETA N. GEN. 1. Sediment particles fine, often forming sediment tubercles throughout five chaetigers. 2 — Sediment particles large, often forming sediment tubercles throughout at least ten chaetigers ............................................................................................................................ 6 2. Anterior shield ventrally continuous ............................................................................3 — Anterior shield ventrally discontinuous; first neurohooks from chaetiger 5 ..................... ........................................................................................................... P. orensanzi n. sp. 3. Median neurochaetae aristate capillaries ....... P. scutigeroides ( Augener, 1918 ) n. comb. , restricted — Median neurochaetae falcate neurohooks ................................................................... 4 4. Body of a single color, not markedly bicolor ............................................................... 5 — Body markedly bicolor, anteriorly whitish, posteriorly dirty orange or pale brownish; first neurohooks from chaetiger 7 .................................................................. P. ehlersi n. sp. 5. Median and posterior neurohooks falcate, robust; notochaetae of middle or posterior regions with longest median articles 5-6 times longer than wide ...... P. coronata ( Ehlers, 1908 ) n. comb. , restricted — Median and posterior neurohooks almost straight, thin; notochaetae of middle or posterior regions with longest median articles three times longer than wide P. antoni ( Kirkegaard, 1996 ) n. comb. 6. Median neurochaetae aristate capillaries ............................................. P. augeneri n. sp. — Median neurochaetae falcate neurohooks ................................................................... 7 7. Neurochaetae markedly sigmoid ............................. P. scutigera ( Ehlers, 1887 ) n. comb. — Neurochaetae feebly falcate, almost straight P. africana ( Rullier, 1965 ) n. comb., n. stat. ETYMOLOGY.— Paratherochaeta n. gen. is derived from a combination of the name of its stem genus, Therochaeta , with the Greek prefix para (beside, near, by), to indicate its close resemblance to it. REMARKS Paratherochaeta n. gen. is closely allied to Therochaeta as indicated in a phylogenetic analysis using morphological features (Salazar-Vallejo et al. 2008). Both genera include species with a longer second chaetiger and at least the first three chaetigers may have a cover of cemented sediment grains. Their main difference is that in Paratherochaeta n. gen. there are no pseudocompound chaetae present, but falcate hooks or capillary chaetae.