Exogone (Parexogone) sexoculata Hartmann-Schröder, 1979

Exogone (Parexogone) sexoculata Hartmann-Schröder, 1979 View in CoL

Fig. 68A–G

Exogone sexoculata Hartmann-Schröder, 1979: 10 , figs. 175–177; 1980a: 56; 1981: 38; 1982: 74; 1986: 45; 1987: 42; 1989: 31; 1990: 55; 1991: 42.

Material examined. AUSTRALIA: NEW SOUTH WALES. 1 specimen, AM W23540, Weeney Bay, Botany Bay, 34°01.3'S 151°09.7'E, mud, 1 m,A. Roach & A. Jones, 30 Mar 1995. 1 specimen,AM W23541, Weeney Bay, Botany Bay, 34°01.3'S 151°09.7'E, mud, 1 m, A. Roach & A. Jones, 30 Mar 1995. 1 specimen, AM W26407, 800 m WSW from tip of airport runway extension, Botany Bay, 33°58.33'S 151°10.22'E, 7 m, Australian Museum Party, 6 Apr 1992. 13 specimens, and 4 specimens on SEM stub, AM W27441, Waratah Bay, Cowan Creek, 33°37.8'S 151°09.9'E, 4.5 m, A. Jones & party, 03 Oct 1980. 11 specimens, AM W196617, small bay in Cowan Creek, Hawkesbury River, 33°39.0'S 151°09.5'E, 7.5 m, A. Jones & party, 04 Oct 1980. SOUTH AUSTRALIA. 1 specimen, AM W26754, Victor Harbour, 35°33'S 138°38'E, algal washings, P.A. Hutchings, 16 Mar 1979. WESTERN AUSTRALIA. 2 specimens, AM W26668, 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. 1 specimen, AM W26669, north east entrance to Goss Passage, Beacon Island, 28°27.9'S 113°46.7'E, dead Acropora, coralline & brown algae on coral substrate, 24 m, P.A. Hutchings, 25 May 1994. 2 specimens, AM W26670, east side of West Wallabi Island, 28°27.9'S 113°40.9'E, in Posidonia australis root mat, plus epifauna, 2 m, P.A. Hutchings, 26 May 1994.

Description. Body small, slender, 3.6 mm long, 0.2 mm wide, 40 chaetigers. Prostomium ovate, wider than long, 2 pairs of large eyes in trapezoidal arrangement, anterior pair larger than posterior eyes, and 2 anterior eyespots; median antenna long, slightly longer than combined length of prostomium and palps, cylindrical, inserted between posterior pair of eyes, lateral antennae small, ovoid, inserted close to inner margin of anterior eyes, slightly in front of line of insertion of median antenna (Fig. 68A). Palps fused along their length, longer than prostomium, forming a triangular, broad piece. Peristomium slightly shorter than following segments; tentacular cirri minute, smaller than lateral antennae. Dorsal cirri small, with slightly bulbous bases, much shorter than parapodial lobes, absent on chaetiger 2 (Fig. 68A). Parapodial lobes ending on a rounded distal papilla. Compound chaetae similar throughout, all bidentate falcigers, with distinct subdistal tooth, short, thin marginal spines and dorsoventral gradation in length, blades 12–13 µm above, 8 µm below; some blades on some specimens slightly longer on anterior parapodia (Fig. 68C,D); parapodia each with about 6–7 compound chaetae. Dorsal simple chaetae from anterior parapodia, distinctly bidentate, with short marginal spines, slender on anterior parapodia (Fig. 68B), thicker on posterior segments (Fig. 68E). Ventral simple chaetae on posterior parapodia, sigmoid, distinctly bidentate, with short marginal spines (Fig. 68G). Solitary acicula distally curved, sometimes with an additional slender, straight acicula on anterior parapodia (Fig. 68F). Pharynx through about 4–5 segments; pharyngeal tooth on anterior rim (Fig. 68A). Proventricle through 4 segments, with 19–20 muscle cell rows.

Distribution. Australia (all States).

Habitat. Sand, mud, algae, dead corals; a common species on shallow water, down to about 24 m depth.