Exogone (Exogone) dispar (Webster, 1879)

Exogone (Exogone) dispar (Webster, 1879) View in CoL

Figs. 81F View Fig , 85A–G

Paedophylax dispar Webster, 1879: 223 , pl. 4, fig. 49, pl. 5, figs. 50–55.

Exogone dispar .–Westheide, 1974: 298, figs. 48, 49; Perkins, 1981: 1090; Uebelacker, 1984: 30–43, fig. 30–36; Campoy, 1982: 290, pl. 21; San Martín, 1984a: 221, pl. 52; Fan et al., 1993: 25, fig. 5.

Exogone (Exogone) dispar .–San Martín, 1991a: 729; 2003: 274, figs. 149, 150; Ruíz-Ramírez & Salazar-Vallejo, 2001: 127, fig. 3 (45–54).

Material examined. AUSTRALIA: WESTERN AUSTRALIA. 1 specimen, AM W26790, Condillac Island, Kimberley region, 14°06'S 125°33'E, sand with scattered bommies and intertidal, 6 m, P.A. Hutchings, 16 July 1988. 2 specimens, AM W26832, inshore reef off Ned’s Camp, Cape Range National Park, 21°59'S 113°55'E, small brown sponges, 1.5 m, J.K. Lowry, 2 Jan 1984. 34 specimens, AM W27016, north end of Long Island, Goss Passage, 28°28.3'S 113°46.3'E, dead coral covered with coralline algae & boring bivalves, 8 m, C. Bryce, 22 May 1994. 7 specimens, AM W27017, north end of Long Island, 28°27.9'S 113°46.3'E, dead coral substrate with coralline & brown algae, 6 m, C. Bryce, 22 May 1994. 2 specimens, AM W27018, southeast end of Long Island, 28°28.8'S 113°46.3'E, dead coral substrate covered with coralline algae, 8 m, P.A. Hutchings, 22 May 1994. 1 specimen, AM W27019, off jetty near Fisheries Hut, Beacon Island, 28°25.5'S 113°47.0'E, dead plate coral substrate— Acropora, Montipora spp., 12 m, P.A. Hutchings, 23 May 1994. 3 specimens, AM W27020, east side of West Wallabi Island, 28°27.9'S 113°40.9'E, in Posidonia australis root mat with epifauna, 2 m, P.A. Hutchings, 26 May 1994. 5 specimens, AM W27021, 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. 7 specimens and 3 specimens on SEM stub, AM W27426, inshore reef off Ned’s Camp, Cape Range National Park, 21°59'S 113°59'E, frilly Caulerpa sp., 1 m, J.K. Lowry, 2 Jan 1984. 1 specimen, AM W27428, inshore reef off Ned’s Camp, Cape Range National Park, 21°59'S 113°55'E, coral rubble covered with algae, 1.5 m, J.K. Lowry, 2 Jan 1984. 6 specimens, AM W27454, north end of beach, Bundegi Reef, Exmouth Gulf, 21°49'S 114°11'E, rocky rubble, coralline algae with green epiphyte, 2 m, H.E. Stoddart, 4 Jan 1984. 30 specimens, AM W27644, north end of beach, Bundegi Reef, Exmouth Gulf, 21°49'S 114°11'E, rocky rubble, brown algae with epiphytes, sediment, 2 m, H.E. Stoddart, 4 Jan 1984.

Description. Body long, slender, filiform, 5 mm long, 0.25 mm wide, 35 chaetigers. Prostomium rounded to oval; 4 eyes in trapezoidal arrangement. Antennae inserted close to each other approximately on middle of prostomium, anteriorly to line between anterior eyes (Fig. 85A); median antenna distinctly longer than lateral antennae, shorter than prostomium and palps together, with a subdistal enlargement; lateral antennae ovate, 1 ⁄ 3 or less than median antenna. Palps broad, fused all along their length, with a dorsal furrow and distal notch, similar in length to prostomium ( Figs. 81F View Fig , 85A). Peristomium similar in length to following segments; tentacular cirri small, ovoid. Dorsal cirri ovoid, similar to tentacular cirri but longer, similar to lateral antennae or slightly shorter, present on all parapodia ( Figs. 81F View Fig , 85A). Anterior parapodia each with 1–2 compound chaetae with unidentate, filiform spiniger-like blades, with short marginal spines (Fig. 85B), about 28–29 µm long; in addition 5–6 compound chaetae with falcigerous blades, bidentate, subdistal tooth long and distal tooth short and moderate marginal spines (Fig. 85C), about 8 µm long. Decreasing number of compound chaetae posteriorly to 1 spiniger-like and 2 falcigers; posterior compound chaetae less spinulated, both on shafts and blades (Fig. 85E,F); blades of spinigerlike chaetae about 18 µm and those of falcigers about 4–5 µm long. Dorsal simple chaetae from anterior segments (4– 5), with rounded tips and finely spinulose subterminally, thicker posteriorly (Fig. 85D). Ventral simple chaetae on posterior parapodia, sigmoid, thick, smooth, bidentate, subdistal tooth longer and more broad than distal tooth (Fig. 85G). Acicula solitary, slender, distally expanded and rounded, with slightly hollowed tip (Fig. 85H). Pharynx long, through 5 segments; pharyngeal tooth located on anterior rim (Fig. 85A). Proventricle through 3–4 segments, with 22 muscle cell rows. Pygidium with 2 long anal cirri.

Distribution. West Atlantic, from Arctic to Florida. Mediterranean. South Africa. Pacific Ocean: Galápagos Islands, Japan, Australia (Western Australia).

Habitat. Sediments, from mud to coarse sand, broken shells, inside corals, amongst algae and seagrasses; intertidal and shallow waters.