Hydroides tambalagamensis Pillai, 1961

Sun, Yanan, Ten, Harry A. & Qiu, Jian-Wen, 2012, Serpulidae (Annelida: Polychaeta) from Hong Kong, Zootaxa 3424, pp. 1-42 : 21-23

Hydroides tambalagamensis Pillai, 1961

( Figure 11 A–J)

Hydroides tambalagamensis Pillai 1961: 36 –38; Imajima 1976a: 231 –232; Imajima and ten Hove 1984: 49.

Material examined. AM W40552, 4 specimens (22°21’N, 114°17’E, Sharp Island, on dead coral, 3 m, May 21, 2009).

Description. TUBE: white, trapezoidal in cross-section, with two long longitudinal ridges. Thick, transparent, chitinous layer present inside the tube. Up to 1.1 mm wide with lumen 0.7 mm.

BRANCHIAE: radioles on each side arranged in semicircle, numbers ranging from 10 to 11 (n=2, µ=10.5±0.7). Interradiolar membrane absent. Terminal filament thin and long, up to 0.5 mm.

PEDUNCLE: smooth, with a brown pigmented constriction near funnel, insertion just below right branchial lobe. Pseudo-operculum club-shaped in two specimens, with an inflated tip in one.

OPERCULUM: with distal verticil inserted into proximal oblique radial symmetrical funnel on long stalk. Verticil dark brown to black, consisting of 7 to 8 spines similar in shape and size (n=3, µ=7.7±0.6); all spines incurving towards centre of crown, but distally curving outwards in a tapering, pointed tip; each spine with a pair of lateral spinules in the middle, and one internal spinule directed to centre of verticil almost level with the lateral spinules. Number of radii ranging from 25 to 29 (n=3, µ=26.7±2.1); light brown, tips chitinized, curving outward. Interradial grooves 1/2 of funnel length ( Figure 11 A). Opercular length from 0.8 mm to 0.9 mm (n=3, µ=0.9±0.1), width from 0.7 mm to 0.8 mm (n=3, µ=0.7±0.1).

COLLAR AND THORACIC MEMBRANES: collar with laciniate edge, continuous with thoracic membranes, forming apron across anterior abdominal chaetigers ending at chaetiger 4.

THORAX: with 7 chaetigers, 6 uncinigerous. Collar chaetae of two types: bayonet with two pointed teeth at base of serrated blade, and smooth capillaries; subsequent chaetae of two sizes (limbate and capillary, Figure 11 B–C). Uncini along entire thorax saw-shaped, with 7 curved teeth including anterior fang ( Figure 11 D–E). Tori of similar size along thorax. Ventral depression present.

ABDOMEN: total number of abdominal chaetigers varies from 39 to 46 (n=2, µ=42.5±4.9). Uncini sawshaped with 5 to 7 teeth including fang anteriorly ( Figure 11 F, G); rasp-shaped posteriorly with 4 to 5 rows of teeth and 8 to 9 teeth in profile view ( Figure 11 H). Chaetae flat trumpet-shaped ( Figure 11 I). Capillaries present posteriorly ( Figure 11 J), glandular pad absent.

SIZE: total worm length: 12.8 mm to 14.0 mm (n=2, µ=13.4±0.8), thoracic width: 0.7 mm to 0.8 mm (n=2, µ=0.8±0.1). Branchiae and operculum accounting for one fourth of entire length.

COLOUR: body yellow to light brown, verticil black.

Habitat. Depth: 6 m, on dead corals.

Distribution. Widely distributed in tropical and subtropical waters of the Indian Ocean and Pacific Ocean.

Figures

FIGURE 11. Hydroides tambalagamensis, AM W 40552. A, operculum. B, limbate chaetae from chaetiger 4. C, details of limbate chaetae from chaetiger 4. D, uncini from chaetiger 4. E, uncini from chaetiger 7. F, anterior abdominal uncini. G, middle abdominal uncini. H, posterior abdominal uncini. I, toothed edge of flat-trumpet chaetae from posterior abdomen. J, posterior abdominal capillary. (Scale bars: A = 100 μm, B = 20 μm, D – G, J = 10 μm, H, I = 2 μm)