Trophoniella indica ( Fauvel, 1928 ) SALAzAR-Vallejo, 2012

SALAzAR-Vallejo, Sergio I., 2012, Revision of Trophoniella Hartman, 1959 (Polychaeta, Flabelligeridae), Zoosystema 34 (3), pp. 453-519 : 453-519

Trophoniella indica ( Fauvel, 1928) n. comb., n. stat.

( Fig. 18 )

Stylarioides eruca indica Fauvel, 1928: 95 , 96, fig. 3hk; 1930: 42, 43, fig. 10h-l; 1932: 180; 1953: 347, fig. 170h-l. — Al-Hakim & Glasy 2004: 38.

TYPE MATERIAL. — Indian Ocean, Bay of Bengal. 1 slide ( IRFA M-33’) with cephalic cage chaetae and neurohooks from anterior chaetigers, in poor shape, from type material, Krusadai Island, Madras, India.

ADDITIONAL MATERIAL. — Indian Ocean, Andaman Sea. 1 slide ( IRFA R-29) with neurohooks from several chaetigers, including posterior ones, Vancauri, Nancowry Island, Nicobar Islands, India.

Bay of Bengal. 15 specimens ( LACM-AHF 2493 ), International Indian Ocean expedition, northern Indian Ocean, stn RH 30, Madras , 2.5 km SE off harbor, directly E of the University building, 15 m, gray mud with little sand, 18.III.1964, H. Sanders (2.0-15.0 mm long, 11-50 chaetigers; smaller specimens having 16- 20 chaetigers, with sediment particles restricted to the anterior and median regions and anchylosed neurochaete from chaetigers 11-13) .

Gulf of Carpentaria, Australia. 1 anterior fragment (NTM 18914), damaged, stn T6a (15°21.77’S, 136°30.70’E), Bing Bong, McArthur River, no depth data, 17.III.1993, Marine Ecology Unit (17 mm long, 1.5 mm wide, cephalic cage 3.5 mm long, 32 chaetigers). — 1 complete specimen (NTM 18915), broken in 2 pieces, stn T9a (15°22.58’S, 136°31.72’E), Bing Bong, McArthur River, no depth data, 17.III.1993, Marine Ecology Unit. — 1 anterior fragment (NTM 18916), without sediment in the posterior region, stn T4d (15°22.65’S, 136°30.30’E), Bing Bong, McArthur River, no depth data, 17.III.1993, Marine Ecology Unit (13 mm long, 2 mm wide, cephalic cage 3.5 mm long, 29 chaetigers).

DISTRIBUTION. — Indian Ocean, from the Krusadai Island, India, to northeastern Australia, in shallow water.

DESCRIPTION

Complete specimen ( NTM 18915), broken in two pieces ( Fig. 18A ), slightly damaged ; body with first three chaetigers reddish, posterior end pale, in regeneration ( Fig. 18B ). Tunic papillated, dorsally and ventrally with large sediment particles (sand, shell fragments, forams and other large particles; NTM 18916 without sediment cover in the posterior region). Body cylindrical, slightly swollen medially, 19.5 (16 + 3.5) mm long, 2 mm wide, cephalic cage 3 mm long (chaetiger 1 chaetae lost), 38 (26 + 12) chaetigers. Body papillae long, capitate, sparse, arranged in longitudinal rows, five dorsally, four ventrally, difficult to detect because of the sediment particles .

Anterior end observed in another specimen (NTM 18916). Cephalic hood tube long, made of two articles, basal ring pigmented, papillated (mostly eroded), distal ring smooth, transparent, margin smooth. Anterior end distorted by eversion of the anterior gut. Prostomium low, no eyes. Caruncle well developed, reaching the end of the branchial tongue-like plate. Palps cylindrical, long, medially and distally eroded; palp keels low, reduced. Lips not detectable due to the anterior gut eversion.Branchiae cirriform, sessile on tongue-like branchial plate, basally narrowed, arranged in two lateral groups, each with about 18 filaments. Branchial filaments longer basally, shorter distally, all shorter than palps. Nephridial lobes basal, cirriform, elongate, separate from the branchial plate.

Cephalic cage (damaged) chaetae 1.5 times longer than body width. Chaetigers 1-3 involved in the cephalic cage; chaetae of chaetiger 1 arranged in short dorsal and ventral series; others in short ventrolateral series. Chaetiger 1 with two chaetae per bundle, one neurochaeta broken; chaetiger 2 with 2-3 chaetae per bundle; chaetiger 3 with five chaetae per bundle. Anterior dorsal margin of first chaetiger papillated, with a median projection with 1(-2) distal papillae. Anterior chaetigers with conical notopodial lobes anteriorly directed, without especially long papillae ( Fig. 18C ). Chaetigers 1-3 progressively larger. Chaetal transition from cephalic cage to body chaetae gradual; anchylosed, bidentate neurohooks start by chaetiger 14. Gonopodial lobes not seen.

Parapodia poorly developed; chaetae emerge from the body wall. Parapodia lateral; median neuropodia ventrolateral. Noto- and neuropodia as short lobes with 4-6 papillae per bundle, being reduced to 2-3 per bundle in posterior chaetigers.

Median notochaetae arranged in short longitudinal series, 5-6 per bundle, as long as 1⁄₃ body width; all notochaetae multiarticulated capillaries, each with articles short basally and medially, distally long ( Fig. 18D , inserts). Neurochaetae multiarticulated capillaries in chaetigers 1-3, replaced by similar bidentate hooks from chaetiger 4, each with a distal swelling, tips bidentate ( Fig. 18E ); replaced completely by chaetiger 14 with smaller, anchylosed hooks. These neurohooks curved distally, darker, neurohooks arranged in transverse series, 4-5 per bundle, each with short rings present to the subdistal, slightly expanded region, blade hyaline, tip bidentate, accessory tooth foliose, passing the fang ( Fig. 18F ).

Posterior end tapering to a blunt cone ( Fig. 18B ), pygidum without sediment, probably in regeneration, with anus terminal; no anal cirri.

REMARKS

The type material of Stylarioides eruca indica , originally deposited in Calcutta, was not available. This combination was originally published as a variety, which would make it unavailable ( ICZN 1999: art. 45.6.3), but it became available because Hartman (1959: 421) listed it as a subspecies ( ICZN 1999: art. 45.6.4.1). This species, however, does not belong in Piromis , but rather fits Trophoniella because its median and posterior neurochaetae are anchylosed, and it differs from other species in the same genus to such a degree that it deserves a new status as T. indica n. comb., n. stat.

Fauvel (1928: 7) provided very short description and few illustrations for S. eruca indica . He regarded his new variety as closely allied to Piromis (olim Stylarioides ) eruca Claparède, 1868 but differing by having longer and thinner neurochaetae. In fact, their neurochaetae are markedly different because in Trophoniella they are anchylosed, or provided with very short anchylosed articles or rings, reaching the medial or subdistal chaetal regions, and the hooks can be subdistally expanded, hyaline, whereas in Piromis neurohooks have longer articles, which are actually articulated, rarely distally expanded, and articles continue to the subdistal chaetal part.

Trophoniella indica n. comb., n. stat. resembles T. enigmatica n. sp. from the Mediterranean Sea and eastern Atlantic because both have dorsal tubercles. They differ, however, besides the branchial features, in the relative start of the anchylosed neurohooks, and about the size of the accessory tooth; thus, in T. indica n. comb, n. stat. the anchylosed neurohooks start by chaetiger 14, whereas they start by chaetiger 40 in T. enigmatica n. sp., and the distal tooth is longer than the fang in T. indica n. comb, n. stat., whereas it is as long as fang in T. enigmatica n. sp.

Many juveniles or recently recruited specimens (LACM-AHF), 0.9-15 mm in length, show that the sediment cover pattern is fixed early during ontogeny. Thus, most specimens have sediment particles throughout the body, but the relative sediment particles density is size-dependent. This might imply that particles are fixed depending on the size, abundance and relative exposure of the body papillae and, at the same time, dorsal tubercles might be size-dependent and consequently, trying to identify some juveniles with the key above which is based on adults, might be misleading. On the contrary, the start of anchylosed neurohooks changes throughout the juvenile development because their start is apparently displaced posteriorly during ontogeny; thus, a 1.7 mm long juvenile has them from chaetiger 5, a 2.3 mm long has them from chaetiger 7, a 2.5 mm long has them from chaetiger 9, and a 15 mm long has them from chaetiger 14, as in the adult.

Figures

FIG. 18. — Trophoniella indica (Fauvel, 1928) n. comb., n. stat., complete specimen (NTM 18915): A, lateral view; B, posterior region, lateral view; C, anterior end, lateral view; D, chaetiger 10, notochaetae (inserts:basal and distal notochaetal regions); E, chaetiger 18, neurochaetae (longest multiarticulate hook separated in two pieces); F, chaetiger 32, neurochaetae (inserts: tips of neurochaetae). Scale bars: A, 1.25 mm; B, 0.6 mm; C, 0.4 mm; D, F, 90 µm; E, 40 µm.