Paratherochaeta scutigeroides ( Augener, 1918 ), 2013

Salazar-Vallejo, Sergio I., 2013, Revision of Therochaeta Chamberlin, 1919 (Polychaeta: Flabelligeridae), Zoosystema 35 (2), pp. 227-263 : 258-260

Paratherochaeta scutigeroides ( Augener, 1918) n. comb., restricted

( Fig. 14 )

Stylarioides scutigeroides Augener, 1918: 444-447 , pl. 6, figs 155, 185 (partim). — Fauvel 1936: 77-78. — Fauvel & Rullier 1959: 181. — Kirkegaard 1959: 43 (partim).

Stylarioides monilifer – Rullier 1965: 46-47 (partim, non delle Chiaje, 1831).

TYPE MATERIAL. — Tropical Eastern Atlantic Ocean. Syntypes of Stylarioides scutigeroides (ZMH V1593), off Nyanga River, Congo, A.Hupfer coll. (anterior fragments, damaged, 6.5-7.0 mm long, 1.0- 1.8 mm wide, cephalic cage 2[broken]- 4 mm long, 18-28 chaetigers; neurohooks start in chaetiger 8 in both syntypes) .

ADDITIONAL MATERIAL. —Tropical Eastern Atlantic Ocean. One specimen ( ZMUC 1800 ), off Bioko, Nigeria, R/V Atlantide, Stat.113 (04°05’N, 07°09’E), 32 m, 22.II.1946 . One specimen ( MNHN 477 ), Sta. 106 (05°59’N, 01°11’E), 32 m, muddy sand, 7.X.1963, A. Crosnier coll. (11.5 mm long, 1.3 mm wide, cephalic cage 2.5 mm long, 43 chaetigers) . Four specimens ( MNHN 449 ), Moroco, Stat. 33 (33º41’15”N, 07º35’51”W), 50 m, 2.VI.1924, and Stat. 54 (33º33’40”N, 07º48’56”W), 40 m, 21.VI.1924 (damaged specimens, one with complete shield, the others without it; one with body wall broken, regenerating the posterior region; many chaetae broken).

DISTRIBUTION. — Western Africa, from Nigeria to Congo, in shallow water (up to 32 m).

DESCRIPTION

Syntypes anterior fragments, most anterior shield eroded or removed ( Fig. 14 A-C). Description based mainly on additional specimen (ZMUC 1800).

Body broken into two portions, orange-reddish anteriorly, paler medially and posteriorly ( Fig. 14D ). Body thinner along few anterior chaetigers, then swollen, continued into a paler region of about same width, cephalic hood exposed; 23(6+17) mm long, 1.5 mm wide, cephalic cage 6 mm long, 72 (18+54) chaetigers.

Tunic thin, cementing sediment particles along chaetigers 1-4, barely continued into chaetiger 5. Body papillae forming sediment tubercles, arranged in single transverse bands in chaetigers 1-4, decreas - ing in size and becoming more abundant posteriorly, continued to the last segment; other papillae smaller, giving a finely granulose appearance to the body wall once temporarily stained with methyl green.

Cephalic tube partly-exposed (completely exposed in one syntype, Fig. 14 A-C), long, narrow, made of two finely rugose, transparent rings, basal one wider. Anterior end not dissected to avoid further damage. Larger syntype with head exposed, palp, branchiae and other features lost ( Fig. 14A , insert).

Cephalic cage chaetae as long as four times body width. Chaetigers 1-2 involved in cephalic cage, parapodia of chaetiger 2 laterally displaced, chaetae almost in a continuous series; chaetiger 3 chaetae twice as long as those in chaetiger 4, not contributing to cage. Cephalic cage chaetae arranged in short ventrolateral series; chaetiger 1 with two noto- and one neurochaetae per bundle; chaetiger 2 with five chaetae per ramus.

Anterior dorsal margin of first chaetiger with larger, median triangular lobe, and two smaller ones, all projected anteriorly ( Fig. 14E ); ventrally with four triangular lobes, median ones slightly larger than laterals ( Fig. 14F ). Chaetiger 2 with long notochaetal papillae. Chaetigers 1-3 of varying length, first and third shorter than second one, with a posterior constriction; chaetiger 4 about as long as chaetiger 1; following chaetigers shorter, much wider than long. Sand cemented anterior shield surrounding chaetigers 1-3. Chaetal transition from cephalic cage to body chaetae abrupt; aristate neurochaetae present from chaetiger 8. Gonopodial lobes not seen.

Parapodia well-developed in chaetigers 1-4, flat short lobes, with long papillae; remaining parapodia poorly developed, chaetae emerge from body wall. Parapodia lateral, median neuropodia ventrolateral. Noto- and neuropodia slightly elevated lobes, without long papillae; one-two longer capitate papillae between noto- and neuropodia. Noto- and neuropodia distant to each other.

Median notochaetae arranged in short longitudinal series; all notochaetae multiarticulated capillaries, articles long throughout the chaeta, five-six per bundle, about as long as ½ body width. Neurochaetae multiarticulated capillaries in chaetigers 1-7; aristate neurochaetae from chaetiger 8, basally annulated, reddish, articles medium sized, less defined distally; neurospines arranged in a ∪-pattern, four-five per bundle in anterior chaetigers ( Fig. 14G ), eight-nine in median and posterior chaetigers ( Fig. 14H ).

Posterior end unknown.

REMARKS

For the original description of Stylarioides scutigerioides, Augener (1918: 446) combined two different forms under the same species. The main difference between them lies on the neurochaetae; for one of the forms, he stated: “Jedenfalls sehen die Ventralborsten, so bei meinen beiden vollständigen Exemplaren, anders aus als bei St. scutiger , dessen Ventralborsten als schwache Haken zu bezeichnen sind. Bei einem dritten Exemplar, einem Tier vom Nyanga-Fluss, das im Habitus, in der Färbung und in der Form des verstümmelten Hinterendes dem St. scutiger ganz ähnlich ist, haben die Ventralborsten mehr Ähnlichkeit mit der Ehlers�schen Abbildung dieser Borsten von St. scutiger ... ” This translates as: “Anyway, the ventral bristles in my two complete specimens are different from St. scutiger , whose ventral bristles are to be marked as weak hooks. With a third specimen, an animal from Nyanga River, that in the outlook, in the coloring and in the form of the mutilated rear end is quite similar to St. scutiger , the ventral bristles have more similarity with the Ehlers’ illustration of the bristles of St. scutiger .” The syntypes and the additional specimen that were used for the redescription have aristate neurochaetae and likely belong to the same species. It would be useful to find additional specimens to evaluate the ontogenetic changes and have a better understanding of this Western African species.

Most Augener syntypes, originally deposited in Hamburg, were lost during WWII bombing. The two syntypes available were included in the description, but had lost the sand cemented anterior cover; however, they come from the Nyanga River and have ventral aristate capillaries from chaetiger 8. Since they are the only type materials left, they have been employed to restrict the species definition. Thus, those forms provided with thin anterior ends and aristate ventral hooks remain in T. scutigeroides , which is therefore restricted in this diagnostic feature, whereas those with better developed sediment tubercles and neurochaetae as multiarticulated capillaries throughout the body were above transferred to another species: P. augeneri n. sp.

Paratherochaeta scutigeroides n. comb. is unique among the species of the genus provided with a thin sediment shield because its neurochaetae are aristate capillaries.

Figures

FIG. 14. — Paratherochaeta scutigeroides (Augener, 1918) n. comb.: A-C, syntypes (ZMH V1593); A, larger syntype in dorsal view, smaller one in oblique dorsal view (insert: head, oblique lateral view); B, larger syntype, anterior end, dorsal view; C, smaller syntype, anterior end, ventral view; D-H, non-type specimen (ZMUC 1800); D, anterior region in dorsal view, posterior region in oblique, lateral view; E, anterior end, dorsal view; F, anterior end, ventral view; G, chaetiger 9, right parapodium (insert: neurochaetae); H, chaetiger 45, right parapodium, (insert: neurochaetae). Scale bars: A, 1 mm; B, E, F, 0.7 mm; C, 0.3 mm; D, 2.4 mm; G, 70 µm; H, 100 µm.