Opisthosyllis longicirrata Monro, 1939

Martín, Guillermo San, Hutchings, Pat & Aguado, María Teresa, 2008, Syllinae (Polychaeta, Syllidae) from Australia. Part. 2. Genera Inermosyllis, Megasyllis n. gen., Opisthosyllis, and Trypanosyllis, Zootaxa 1840, pp. 1-53 : 28-32

Opisthosyllis longicirrata Monro, 1939

Figs 20B–F, 21, 22A–H, 23A–D

Opisthosyllis longicirrata Monro, 1939: 389 , text-figs. 300, 301. – Fauvel 1953: 154, figs 77f–i. – Imajima 1966b: 228, text-fig. 41 a–j.

Material examined. AUSTRALIA, WESTERN AUSTRALIA: Kimberleys, W side of Cassini Island, 13° 57'S, 125° 37'E, low tide, coll. P.A. Hutchings, 18 Jul 1988, 1 ( AM W31390); Fenelon Island, 14° 08'S, 125° 41'E, limestone reef, coll. P.A. Hutchings, 17 Jul 1988, 1 ( AM W31389); Bernouli Island, 15° 00'S, 124° 47'E, intertidal, coll. P.A. Hutchings, 12 Jul 1988, 1 (on SEM stub), ( AM W31428); Inshore reef off Ned's Camp, Cape Range National Park, 21° 59'S, 113° 59'E, 1 m, frilly alga Caulerpa sp. , coll. J.K. Lowry, 2 Jan 1984, 2 ( AM W31388); Near Neds Camp, Cape Range National Park, 21° 59'S, 113° 55'E, 1 m, small purple sponge with algae & sticky sediment, coll. H.E. Stoddart, 2 Jan 1984, 1( AM W29498); Exmouth Gulf, Bundegi Reef, N end of beach, 21° 49'S, 114° 11'E, 2 m, rocky rubble with sediment, brown alga with epiphytic growth, coll. H.E. Stoddart, 4 Jan 1984, 1 ( AM W31387); N end of Long Island, Goss Passage, 28° 27' 54"S, 113° 46' 18"E, 6 m, dead coral substrate, covered in coralline algae, coll. C. Bryce, 22 May 1994, 1 ( AM W31392); Goss Passage, Beacon Island, 28° 25' 30"S, 113° 47'E, 8 m, dead plates of Acropora sp. , covered in coralline algae, coll. P.A. Hutchings, 19 May 1994, 2 ( AM W31391); Off jetty adjacent to Fisheries Hut, Beacon Island, 12 m, 28° 25' 30"S, 113° 47'E, dead coral substrates, plate-like Acropora , Montipora spp. , coll. P.A. Hutchings, 23 May 1994, 1 ( AM W31393); Goss Passage, Beacon Island, 28° 25' 30"S, 113° 47'E, 8 m, dead plates of Acropora sp. , covered in coralline algae, coll. P.A. Hutchings, 22 May 1994, 2 ( AM W31394).

Description. Longest specimen examined 17 mm long, 1 mm wide, 64 chaetigers. Body long, white, margins non-coloured, but minute dark spots on dorsum ( Fig. 21). Prostomium oval; 4 eyes in open trapezoidal arrangement. Palps broad, longer than prostomium ( Figs 20C, 21). Median antenna arising from middle of prostomium, with 37–40 articles, twice as long as combined length of prostomium and palps; lateral antennae shorter than median antenna, about 2/3 of its length, with 25–30 articles. Lateral margins of prostomium cili- ated ( Fig. 20C, D) Peristomium dorsally reduced ( Figs 20C, 21). Dorsal tentacular cirri markedly longer than median antenna, with about 50 articles about twice as long as ventral ones. Dorsal cirri all long ( Figs 20B, E, 21, 22A), several times longer than body width, with basal cirrophore, whip-shaped, alternating in length and number of articles; most anterior segments slightly longer than dorsal tentacular cirri with more than 100 articles, from chaetiger 4 long, more than three times longer than body width, with about 45–55 articles at midbody. Parapodia conical, dorsally bilobed ( Figs 20F, 21), each lobe ending in small papilla. Ventral cirri digitiform, shorter than parapodial lobe. Compound chaetae heterogomph, with bidentate blades, margin with short spines, usually longer basally. Most anterior chaetae with marked dorso-ventral and antero-posterior gradation ( Figs 20F, 22B, C, 23A, B), elongated with slender shafts, becoming thicker posteriorly, with shorter and wider blades, more strongly bidentate posteriorly and ventrally ( Figs 22E, 23C, D); dorsal simple chaeta on posterior segments, unidentate, smooth ( Fig. 22G); ventral simple chaeta on far posterior segments, bidentate, both teeth similar, with small sub-distal spines, smooth ( Fig. 22H). Aciculae distally blunt, decreasing antero-posteriorly from 4 ( Fig. 22D), to 2 ( Fig. 22F) and 1 on most posterior parapodia ( Fig. 22G). Pharynx extending from chaetiger 2 to 9; pharyngeal tooth on chaetiger 8–9 ( Fig. 21). Proventricle through 7 segments, with about 30 muscle cell rows.

Habitat. Found among dead corals and algae; in intertidal and shallow depths.

Distribution. Australia (Western Australia, New South Wales). Reported from Indo-Pacific, Tahití, Maldives Islands, Red Sea, Japan.