Exogone (Exogone) aristata Hartmann-Schröder, 1982

Guillermo San Martin, 2005, Exogoninae (Polychaeta: Syllidae) from Australia With the Description of a New Genus and Twenty-two New Species, Records of the Australian Museum 57, pp. 39-152 : 136-137

Exogone (Exogone) aristata Hartmann-Schröder, 1982

Fig. 84A–M

Exogone aristata Hartmann-Schröder, 1982: 75 , figs. 69–72; 1989: 30.

Material examined. AUSTRALIA: WESTERN AUSTRALIA. 1 specimen, AM W26988, north end of Long Island, 28°27.9'S 113°46.3'E, dead coral algae covered in coralline & brown algae, 6 m, C. Bryce, 22 May 1994. 1 specimen, AM W26989, northeast entrance to Goss Passage, Beacon Island, 28°27.9'S 113°46.7'E, dead Acropora , coral substrate covered in algae, 24 m, P.A. Hutchings, 25 May 1994. 3 specimens, AM W26990, off south end of Long Island, Beacon Island, 28°28.8'S 113°46.3'E, dead coral substrate covered in coralline algae, 5 m, P.A. Hutchings, 25 May 1994. 3 specimens, and 1 specimen on SEM stub, AM W27460, inshore reef off Ned’s Camp, Cape Range National Park, 21°59'S 113°55'E, green algae, 1.5 m, R.T. Springthorpe, 2 Jan 1984.

Description. Body long and slender, filiform, 2.6 mm long, 0.2 mm wide, 42 chaetigers. Prostomium oval, wider than long; 4 large eyes in trapezoidal arrangement; antennae inserted between anterior eyes; median antenna long, cylindrical, slightly longer than combined length of prostomium and palps, lateral antennae inserted close to eyes, about ¼ of length of median antenna (Fig. 84A). Palps long, triangular, fused along their length, with a dorsal furrow. Peristomium similar to following segments, covering dorsally posterior margin of prostomium. Tentacular cirri small, papilliform, much shorter than lateral antennae (Fig. 84A). Dorsal ciri ovoid, shorter than parapodial lobes, present on all segments (Fig. 84A). Parapodia each with 1 (sometimes 2 on anterior parapodia) compound chaetae hemigomph, distally spinose, with spiniger-like blade, distally curved, bifid, with short marginal spines, except 2–3 distalmost ones which are longer and erect, extending beyond tip (Figs. 84B,G,J); in addition compound falcigers 5–6 on anterior parapodia diminishing to 3 on posterior parapodia, with subdistal tooth long and broad and short distal tooth, moderate marginal spines, except 2–3 distalmost ones, long, erect, extending beyond tip (Figs. 84C,H,K); blades both of spiniger-like chaetae and falcigers provided with several rows of marginal spines. Blades of spiniger-like chaetae about 28 µm on anterior parapodia, 37 µm on midbody, 12 µm on posterior parapodia. Blades of falcigers about 10 µm on anterior parapodia, 16–18 µm on midbody, 4–5 µm on posterior parapodia. Dorsal simple chaetae from post-proventricular parapodia, distally bidentate, thicker posteriorly, with 6–8 long, thin spines (aristae) (Figs. 84D,E,F,I). Ventral simple chaetae on posterior parapodia, sigmoid, bidentate, with long subdistal tooth and short distal tooth, provided with several long subdistal spines, 2 distalmost ones much longer than other spines, erect, extending beyond tip of chaeta (Fig. 84L). Acicula solitary, slender, distally expanded and rounded (Fig. 84M). Pharynx long and slender, through about 4 segments; pharyngeal tooth on anterior rim (Fig. 84A). Proventricle short, through 1½–2 segments, with about 15 muscle cell rows. Pygidium with 2 long anal cirri.

Distribution. Australia (New South Wales, Western Australia).

Habitat. Amongst Posidonia and algae, in dead corals; intertidal to about 24 m depth.