Odontosyllis gravelyi Fauvel, 1930

San Martin, G & Hutchings, PA, 2006, Eusyllinae (Polychaeta: Syllidae) from Australia with the Description of a New Genus and Fifteen New Species, Records of the Australian Museum 58, pp. 257-370 : 292-294

Odontosyllis gravelyi Fauvel, 1930

Figs 27C–F, 28A–H, 29A–F

Odontosyllis gravelyi Fauvel, 1930: 16 , figs. 3–4; 1953: 160, figs. 81–82.

Material examined. AUSTRALIA: NEW SOUTH WALES: Careel Bay, Pittwater , 33°37'S 151°19'E, Zostera , coll. P.A. Hutchings, 4 Nov 1973 ( AM W11110) . QUEENSLAND: Calliope R., 23°51'S 151°10'E, coll. P. Saenger, 1974, 7 ( AM W199367 ) . Triangular Islets, Shoalwater Bay , 22°23'S 150°31'E, coll. J.A. Lewis & J.R. Forsyth, 1981, 10 on SEM stub ( AM W202645 ) .

Description. Body 14 mm long, 1.2 mm wide, with 50 chaetigers; distinct, median longitudinal black band, and large lateral spots, resembling 3 longitudinal stripes ( Fig. 28A). Prostomium small, hidden under most anterior segments ( Figs 27C, 28A–C) (probably contracted), with 2 black lateral spots and posterior transverse band; antennae short and slender, inserted in front of anterior eyes, median antenna longer than lateral antennae, inserted slightly posteriorly ( Figs 27C, 28B,C), similar to combined length of prostomium and palps. Prostomium with 2 slightly raised mounds with minute pores (see arrows Fig. 27D,E). Two densely ciliated, semi-circular nuchal organs ( Fig. 27C,D). Palps small, fused basally, ventrally folded. Peristomium

(G) long-bladed compound chaetae, midbody; (H) falcigers, midbody. Holotype

AM W11110, except B, AM W202645. Scales: A–C,E: 0.8 mm, D: 0.2 mm, F:

0.18 mm, G,H: 20 µm.

small, dorsally nearly covered by small lobe of chaetiger 1 ( Figs 27C, 28B); tentacular cirri similar to antennae, but slightly longer. Anterior dorsal cirri elongated, smooth, distally tapered, rugose to pseudoarticulate ( Figs 27C, 28A) becoming progressively shorter along body ( Figs 27F, 28D), slightly longer than parapodial lobes. Parapodia with 2–3 parallel lobes ( Figs 27F, 28D, 29A). Ventral cirri short, pillow-shaped ( Figs 27F, 28D). Compound chaetae numerous, shafts distally spinose, and blades of 2 kinds, most dorsal ones with elongate, bidentate blades ( Fig. 28G), short spines on margin, and remaining chaetae with short, triangular, distinctly bidentate blades ( Figs 28H, 29A–E); on midbody, parapodia with about 6–7 compound chaetae of slender type, 37–45 µm in length, and 28–30 chaetae with short blades, all similar, about 16–18 µm in length; compound chaetae slightly longer on anterior parapodia ( Fig. 29A,B). Aciculae slender, distally blunt, numerous in anterior parapodia, reduced to 2–3 on posterior parapodia. Dorsal simple chaetae slender, thin, unidentate ( Fig. 29C). Ventral simple chaetae on posterior parapodia, bidentate, with short spines on margin ( Fig. 29C,F). Pharynx through 3–4 segments, with 5 teeth and 2 lateral plates ( Fig. 28F). Proventricle long, slender ( Fig. 28E), through 9 segments, with about 80 muscle cell rows.

Remarks. The small lobe on the peristomium is not regarded as an occipital flap. This species is characterized by its colour pattern, a lack of an occipital flap, and two kinds of compound chaetae being present. Odontosyllis trilineata Imajima, 2003 has a similar colour pattern and chaetae, but they differ in that O. gravelyi also has long-bladed chaetae, and O. trilineata has a distinct occipital flap and 9 teeth on trepan ( Imajima, 2003).

Habitat. Occurring in coarse sand and gravel and mud, shallow depths often in estuarine conditions.

Distribution. Australia (New South Wales, Queensland) and southeast India.