Exogone (Exogone) heterosetosa McIntosh, 1885

Exogone (Exogone) heterosetosa McIntosh, 1885 View in CoL

Fig. 74A–K

Exogone heterosetosa McIntosh, 1885: 205 , pl. 33, figs. 15–16, pl. 34A, fig. 11; Haswell, 1920a: 221, figs. 11–17; Hutchings & Murray, 1984: 32; Blankenstein & Lana (1986): 63.

Exogone heterochaeta Ehlers, 1897: 51 , pl. 31. Augener, 1913: 247; 1927: 156.

? Exogone heterosetoides australis Hartmann-Schröder & Rosenfeldt, 1988: 44 , fig. 23; Hartmann-Schröder, 1989: 30; 1990: 55; San Martín & Parapar, 1997: 291.

Exogone heterosetoides .–Hartmann-Schröder, 1987: 42, figs. 17– 19. Not Hartmann-Schröder, 1979.

Material examined. AUSTRALIA: QUEENSLAND. 1 specimen, AM W26582, Halifax Bay, north of Townsville, 19°09'S 146°37'E, 2 m, Queensland Nickel Pty Ltd, Feb 1985. NEW SOUTH WALES. 3 specimens, AM W23537, 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 W23904, Pittwater, 33°35.79'S 151°18.30'E, sand, 14.8 m, Australian Museum Party, 3 Jun 1994. 1 specimen, AM W26430, 100 m northwest of Split Solitary Island, 30°14.0'S 153°10.8'E, mixed red algae, 15 m, S.J. Keable, 7 Mar 1992. 2 specimens,AM W26431, Manta Reef, North West Solitary Island, 30°01.5'S 153°16.5'E, lace bryozoan, 19 m, R.T. Springthorpe, 25 Jun 1992. 6 specimens,AM W26432, southwest side of South Solitary Island, 30°12.0'S 153°16.0'E, coral rubble, 18 m, R.T. Springthorpe, 24 Jun 1992. 1 specimen, AM W26468, east of Malabar, Sydney, 33°58.60'S 151°17.85'E, 79.8 m, Fisheries Research Institute (NSW), 8 Dec 1995. 1 specimen, AM W26469, east of Malabar,Sydney, 33°58.76'S 151°17.90'E, 80.5 m, Fisheries Research Institute (NSW), 22 Aug 1995. 6 specimens, AM W26470, just south of Botany Bay, Sydney, 34°03.20'S 151°14.55'E, 78.2 m, Fisheries Research Institute (NSW), 21 Jun 1996. 2 specimens, AM W26471, east of Malabar, Sydney, 33°58.72'S 151°17.95'E, 81.9 m, Fisheries Research Institute (NSW), 22 Aug 1995. 1 specimen, AM W26472, east of Malabar, Sydney, 33°58.72'S 151°18.00'E, 82 m, Fisheries Research Institute (NSW), 22 Aug 1995. 1 specimen, AM W26473, east of Malabar, Sydney, 33°58.76'S 151°18.00'E, 82.6 m, Fisheries Research Institute (NSW), 22 Aug 1995. 1 specimen, AM W26474, east of Malabar, Sydney, 33°58.60'S 151°18.00'E, 81.6 m, Fisheries Research Institute (NSW), 15 Nov 1995. 1 specimen,AM W26475,east of Malabar,Sydney,33°58.60'S 151°17.95'E, 81.5 m, Fisheries Research Institute (NSW), 19 Dec 1995. 1 specimen, AM W26530, South Ledge, Cook Island, 28°11.65'S 153°34.63'E, purple finger sponge, 12 m, A.R. Parker, 9 Jun 1993. 4 specimens, AM W26531, 100 m north west of Julian Rocks, Byron Bay, 28°36.8'S 153°37.8'E, shell and gravel, 15 m, E.L. Albertson et al., 3 Mar 1992. 14 specimens, AM W26614, north east corner of Clark Island, 33°51.85'S 151°14.47'E, encrustation on outside of bottle, 5 m, P.A. Hutchings, 17 Apr 1996. 3 specimens,AM W26636, Grotto Point, Port Jackson, 33°49'S 151°15'E, algae, 4 m, P. Colman, 18 July 1983. 10 specimens,AM W26638, Crowdy Head, 31°50'S 152°45'E, brown algae in rock pools, J.K. Lowry, 13 Jan 1982. 2 specimens, AM W26641, north east corner of Clark Island, 33°51.85'S 151°14.47'E, 5 m, P.A. Hutchings, 17 Apr 1996. 14 specimens,AM W26656, north east corner of Clark Island, 33°51.85'S 151°14.47'E, encrustation on outside of bottle, 5 m, P.A. Hutchings, 17 Apr 1996. 3 specimens, AM W26729, mid point of Aislings Beach, Twofold Bay, 37°05'S 149°56'E, benthic, 32.9 m, S. Keable & P. Albertson, 21 Feb 1985. 1 specimen, AM W26730, Cararma Inlet, Jervis Bay, 35°0'S 150°46.5'E, Zostera capricorni, L. Howitt, Mar 1989 . 2 specimens,AM W26731, 100 m north west of Split Solitary Island,30°14.0'S 153°10.8'E, gravel under rocks, 15 m, R. Gentle, Solitary Is. Underwater Research Group, 7 Mar 1992. 1 specimen, AM W26794, 100 m north west of Split Solitary Island, 30°14'S 153°10.8'E, encrusting algae and ascidians, 16 m, E.L. Albertson, 7 Mar 1992. 1 specimen, AM W27462, small bay in Cowan Creek, Hawkesbury River, 33°39.0'S 151°09.5'E, 7.5 m, A. Jones et al., 04 Oct 1980. 1 specimen, AM W196624, Waratah Bay, Cowan Creek, 33°37.8'S 151°09.9'E, 4.5 m,A.Jones et al., 3 Oct 1980.SOUTH AUSTRALIA. 1 specimen, AM W26759, Victor Harbour, 35°33'S 138°38'E, Zostera washings, P.A. Hutchings, 16 Mar 1979. 1 specimen, AM W26760, Billy Lights Point, Port Lincoln, 34°45'S 135°53'E, stone washings from sheltered intertidal rocks, 0 m, I. Loch, 15 Feb 1985. 4 specimens, AM W26761, Elliston Reef, 33°39'S 134°53'E, algae from reef flat at low tide, P.A. Hutchings, 11 Mar 1979.1 specimen,AM W26762, Maston Point,American River, Kangaroo Island, 35°47'S 137°46'E, clumps of sponge in channel below wharf, 5 m, P.A. Hutchings, 02 Mar 1979. WESTERN AUSTRALIA. 1 specimen, AM W26823, Red Bluff, Kalbarri, 27°42'S 114°09'E, brown alga from surf zone on rocky shore, 0.5 m, H.E.Stoddart, 9 Jan 1984.1 specimen, AM W27056, Goss Passage, Beacon Island, 28°25.5'S 113°47.0'E, dead Acropora plates with sponges, ascidians & algae, 23 m, P.A. Hutchings, 19 May 1994. 10 specimens, AM W27057, 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. 3 specimens, AM W27058, 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 1994.1 specimen,AM W27059, northeast entrance to Goss Passage, Beacon Island, 28°27.8'S 113°46.7'E, dead branching Acropora substrate covered with algae, 24 m, P.A. Hutchings, 25 May 1994. 2 specimens,AM W27060, 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. 1 specimen on SEM stub, AM W27678, west of Penguin Island, Warnbro Sound, 32°20'S 115°43'E, dead reef sponges, 5 m, P.A. Hutchings, 21 Mar 1993.

Description. Body proportionally short, broad, 3–4 mm long, 0.23 mm wide, 30–40 chaetigers. Prostomium oval, wider than long; 4 thick eyes in trapezoidal arrangement. Median antenna long, cylindrical, usually with a subterminal enlargement, slightly longer than prostomium and palps together, inserted close to line between posterior eyes; lateral antennae similar in length to prostomium, cylindrical, inserted between median antenna and each posterior eye (Fig. 74A). Palps broad, relatively short, similar in length to prostomium or slightly shorter, fused along their length, with a dorsal furrow and a distal notch (Fig. 74A). Peristomium similar in length to following segments; tentacular cirri ovoid, much shorter than lateral antennae. Dorsal cirri similar to tentacular cirri, slightly longer, absent on chaetiger 2 (Fig. 74A), shorter than parapodial lobes. Most anterior parapodia each with about 5–7 compound chaetae, all compound chaetae heterogomph falcigers, with long subdistal teeth and small, indistinct distal teeth, and short marginal spines (Fig. 74C), about 6–7 µm long; from about chaetiger 4–5 parapodia with 4–6 similar compound falcigers (Fig. 74F) and solitary strongly modified spinigerlike, distally spinose on shaft, and blade triangular, large on bases, proportionally short, about 15–16 µm long, distally minutely bidentate (Fig. 74E); from midbody posteriorly spiniger-like chaetae with shorter, more strongly triangular blades (Fig. 74H), indistinctly bidentate, about 14 µm long, in addition 3–4 falcigers with short blades (Fig. 74I), about 4– 5 µm long. Dorsal simple chaetae from anterior parapodia, with rounded tips and finely spinulose subterminally, thicker posteriorly (Figs. 74B,D,G).Ventral simple chaetae on posterior parapodia, sigmoid, nearly smooth, with long subdistal tooth and short, small distal tooth (Fig. 74J).Acicula solitary, distally rounded (Fig. 74K). Pharynx through 4 segments; pharyngeal tooth on anterior rim (Fig. 74A). Proventricle through 3 segments, with about 20 muscle cell rows.

Remarks. The Australian specimens agree with Haswell’s (1920a) description of E. heterosetosa ; the original description did not specify the length of the median antenna, because “the state of the preparation renders its presence doubtful”(McIntosh, 1885); subsequent descriptions of the species, however, show a long median antenna.

Distribution. Subantarctic seas. Australia (New South Wales, South Australia, Tasmania, Victoria, Western Australia, Queensland).

Habitat. All substrates: mud, sand, gravel, dead corals, algae, sponges. From shallow waters to about 600 m depth.