Exogone (Exogone) breviantennata Hartmann-Schröder, 1959

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 : 141-142

Exogone (Exogone) breviantennata Hartmann-Schröder, 1959

Figs. 81E , 89A–I

Exogone breviantennata Hartmann-Schröder, 1959: 125 , figs. 75– 78; Zottoli & Long, 2000: 502, figs. 1–5.

Exogone (Exogone) breviantennata .–San Martín, 1991a: 730, fig. 8; Pascual et al., 1996: 70.

Exogone ovalis Hartmann-Schröder, 1960: 106 , figs. 131–133.

Exogone breviantennata ovalis Hartmann-Schröder, 1974c: 28 .

Exogone occidentalis Westheide, 1974: 305 , fig. 52; Russell, 1991: 59, fig. 4.

Exogone verugera .–Not Claparède, 1868; Haswell, 1920a: 219, pl. 17, figs. 7–10; Berkeley & Berkeley, 1948: 78, fig. 116; Day, 1967: 272, fig. 12.10 g–l; Gardiner, 1976: 132, fig. 11 a– e; Imajima, 1966: 399, fig. 3; Rioja, 1943: 221, figs. 12–16.

Material examined. AUSTRALIA: QUEENSLAND. 1 specimen, AM W26456, 100 m off Mangrove Beach, Lizard Island, 14°40'S 145°28'E, medium grained sediment, 3 m, A.R. Jones & C. Short, 13 Oct 1978, B3–3. 4 specimens,AM W26457, lagoon entrance, Lizard Island, 14°40'S 145°28'E, medium to fine sediment, 18 m, A.R. Jones & C. Short, 9 Oct 1978. 3 specimens, AM W26458, 100 m off Mangrove Beach, Lizard Island, 14°40'S 145°28'E, medium sediment, 3 m, A. Jones & C. Short, 13 Oct 1978. 1 specimen, AM W26459, Lizard Island, 14°40'S 145°28'E, A.R. Jones & C. Short, Oct 1978. 1 specimen, AM W26460, 600 m southwest of Research Point, Lizard Island, 14°40'S 145°28'E, coarse to medium grained sediment, 4.5 m, A.R. Jones, C. Short, 10 Oct 1978. 2 specimens, AM W26461, 100 m off Mangrove Beach, Lizard Island, 14°40'S 145°28'E, coarse to medium sediment, 3 m, A.R. Jones & C. Short, 13 Oct 1978. 3 specimens, AM W26462, between bommies inside lagoon entrance, Lizard Island, 14°40'S 145°28'E, medium to fine sediment, 18 m, A.R. Jones & C. Short, 9 Oct 1978. 1 specimen, AM W26463, 100 m off Chinamans Ridge, Watsons Bay, Lizard Island, 14°40'S 145°28'E, sand, 9 m, A.R. Jones & C. Short, 13 Oct 1978. 2 specimens, AM W26464, between bommies inside lagoon entrance, Lizard Island, 14°40'S 145°28'E, medium to fine sediment, 18 m, A.R. Jones & C. Short, 9 Oct 1978. 3 specimens, AM W26465, Triangular Island, Shoalwater Bay, 22°23'S 150°31'E, J.A. Lewis & J.R. Forsyth, 1981. 4 specimens, AM W26466, Triangular Island, Shoalwater Bay, 22°23'S 150°31'E, J.A. Lewis & J.R. Forsyth, 1981. WESTERN AUSTRALIA. 2 specimens, AM W26804, 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. 1 specimen, AM W27000, Goss Passage, Beacon Island, 28°25.5'S 113°47.0'E, dead branching coral covered with coralline algae, 10 m, P.A. Hutchings, 18 May 1994. 7 specimens, AM W27001, Goss Passage, Beacon Island, 28°25.5'S 113°47.0'E, dead Acropora plates covered in sponges, ascidians & algae, 23 m, P.A. Hutchings, 19 May 1994. 16 specimens, AM W27002, Goss Passage, Beacon Island, 28°25.5'S 113°47.0'E, dead Acropora plates covered in coralline algae, 8 m, P.A. Hutchings, 19 May 1994. 6 specimens,AM W27003, Goss Passage, Beacon Island, 28°25.5'S 113°47.0'E, dead Acropora plates covered in coralline algae, 20 m, P.A. Hutchings, 20 May 1994. 4 specimens, AM W27004, Goss Passage, Beacon Island, 28°25.5'S 113°47.0'E, dead coral plates covered in coralline algae, 8 m, P.A. Hutchings, 22 May 1994. 3 specimens, AM W27005, 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. 2 specimens, AM W27006, 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. 5 specimens, AM W27007, east side of West Wallabi Island, 28°27.9'S 113°40.9'E, in Posidonia australia root mat, with epifauna, 2 m, P.A. Hutchings, 26 May 1994. 3 specimens, AM W27008, northeast entrance to Goss Passage, Beacon Island, 28°27.9'S 113°46.7'E, dead branching Acropora with coralline and brown algae, 24 m, P.A. Hutchings, 25 May 1994. 9 specimens, AM W27009, northeast entrance to Goss Passage, Beacon Island, 28°27.9'S 113°46.7'E, dead plate coral covered with coralline algae, 8 m, P.A. Hutchings, 25 May 1994. 1 specimen, AM W27010, Wallabi Island group, 28°34.65'S 113°46.46'E, coral rubble & sponges, 49 m, P.A. Hutchings on FRV “Flinders”, 28 Jun 1994. 2 specimens, AM W27011, East Montlivet Island, 15°06'S 125°18'E, 6 m, P.A. Hutchings, 16 July 1988. 11 specimens, and 2 specimens on SEM stub, AM W27433, 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. 1 specimen, AM W27443, Bush Bay, 30 km south of Carnarvon, 25°10'S 113°39'E, shallow sand flats, 0.5 m, J.K. Lowry and H.E. Stoddart, 6 Jan 1984.

Description. Body long, slender, filiform, 3.7 mm long, 0.17 mm wide, 46 chaetigers. Prostomium ovate, wider than long; 4 eyes in trapezoidal arrangement. Antennae small, papilliform to ovate, inserted close to each other, between or slightly in front of anterior eyes, median antenna slightly longer than lateral antennae ( Figs. 81E , 89A). Palps longer than prostomium, completely fused along their length, with a dorsal furrow and a distal notch, forming a triangular piece ( Figs. 81E , 89A). Peristomium similar in length to following segments or slightly shorter; tentacular cirri minute, papilliform. Dorsal cirri small, similar to lateral antennae, present on all segments ( Figs. 81E , 89A). Anterior and midbody parapodia each with one compound chaeta, spiniger-like, bifid blade, with hemigomph articulation, shaft provided with long, subdistal spines; blade provided with long to moderate marginal spines, about 22–23 µm long (Fig. 89C), and 4 compound, heterogomph falcigers, shafts provided with long subdistal spines, and short blades, provided with long subdistal tooth and short distal tooth, and moderately long marginal spines (Fig. 89D), 10–12 µm long. Posteriorly compound chaetae becoming less spinose; numbers decreasing to 1 compound spiniger-like (Fig. 89G) and 2 falcigers (Fig. 89H) on posterior parapodia. Dorsal simple chaetae from anterior parapodia, usually from chaetiger 1, slender, with rounded tips and finely spinulose subterminally (Fig. 89B), progressively thicker posteriorly, bidentate, with long subdistal tooth and short distal tooth (Fig. 89E). Ventral simple chaetae on posterior parapodia, sigmoid, smooth, bidentate with long subdistal tooth and short distal tooth (Fig. 89F). Solitary acicula, slender, distally rounded (Fig. 89I). Pharynx through 4 segments; pharyngeal tooth on anterior rim (Fig. 89A). Proventricle short, through 2 segments, with about 17 muscle cell rows.

Remarks. Small, young specimens of E. (E.) africana can easily be confused with specimens of E. (E.) breviantennata ; the latter, however, is more slender proportionally, with shorter proventricle, and the compound chaetae are more distinctly spinose. Furthermore, E. (E.) breviantennata is only present in tropical areas, and E. (E.) africana is distributed all around Australia, but appears to be less abundant in tropical waters.

Distribution. Presumably circumtropical. Australia (Queensland, Western Australia).

Habitat. Present on all kinds of substrates, from fine to coarse sand, algae, seagrasses, inside dead corals, sponges. Intertidal to about 49 m depth.

Figures

Fig. 81. SEM of Exogone (Exogone) longicornis, (A) anterior end, dorsal view. SEM of Exogone (Exogone) goorapuranga, (B) anterior end, dorsal view. (C) detail of nuchal organs. (D) posterior end, lateral view. SEM of Exogone (Exogone) breviantennata, A, anterior end, dorsal view. SEM of Exogone (Exogone) dispar, A, anterior end, dorsal view.