Paratherochaeta, Salazar-Vallejo, 2013

Salazar-Vallejo, Sergio I., 2013, Revision of Therochaeta Chamberlin, 1919 (Polychaeta: Flabelligeridae), Zoosystema 35 (2), pp. 227-263 : 245-246

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.