Exogone (Exogone) heterosetoides Hartmann-Schröder, 1979

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 : 126-128

Exogone (Exogone) heterosetoides Hartmann-Schröder, 1979

Figs. 75A–I, 76A–D

Exogone heterosetoides Hartmann-Schröder, 1979: 110 , figs. 171– 174. Not Exogone heterosetoides Hartmann-Schröder, 1987: 42 , figs. 17–19.

Material examined. AUSTRALIA: NEW SOUTH WALES. 8 specimens, AM W26374, south of Worang Point, Twofold Bay, 37°03.5'S 149°56.5'E, benthic sediment, 6.1 m, S. Keable & P. Albertson, 21 Feb 1985. 3 specimens, AM W26375, east of Lookout Point, Twofold Bay, 37°5'S 149°56'E, benthic sample, 27.4 m, S. Keable & P. Albertson, 21 Feb 1985. 2 specimens, AM W26376, 100 m north west of Split Solitary Island, 30°14.0'S 153°10.8'E, gravel under rocks, 17 m, R. Gentle, Solitary Islands Underwater Research Group, 7 Mar 1992. 1 specimen, AM W26377, Split Solitary Island, 30°15'S 153°11'E, 17 m. 1 specimen, AM W26537, 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 W26547, 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 W26643, Bottle and Glass Rocks, Port Jackson, 33°50.9'S 151°16.2'E, airlift, 12 m, G. Clark, 11 Dec 1989. 1 specimen, AM W26653, Barrenjoey Head, Broken Bay, 33°35'S 151°20'E, algae on rocky substrate, 5 m, J.K. Lowry et al., 22 Apr 1983. 1 specimen, AM W26728, north of Honeysuckle Point, Twofold Bay, 37°5'S 149°56'E, benthic sample, 31.1 m, S. Keable, P. Albertson, 21 Feb 1985. 2 specimens, AM W26732, Murrays Beach, Jervis Bay, ACT, 35°07.5'S 150°45.5'E, 9 m, P.A. Hutchings, 23 Jan 1973. SOUTH AUSTRALIA. 1 specimen, AM W26757, Victor Harbour, 35°33'S 138°38'E, algae, P.A. Hutchings, 16 Mar 1979. 1 specimen, AM W26758, Sleaford Bay, Port Lincoln, 34°54'S 135°47'E, algal washings, P.A. Hutchings, 10 Mar 1979. WESTERN AUSTRALIA. 1 specimen, AM W26825, outer edge of Ningaloo Reef off Ned’s Camp, Cape Range National Park, 21°59'S 113°54.5'E, coral rubble, brown alga, 12 m, J.K. Lowry, 2 Jan 1984. 1 specimen, AM W26831, Bundegi Reef, near Point Murat, Exmouth Gulf, 21°49'S 113°11'E, small octocorals, 9 m, R.T. Springthorpe, 4 Jan 1984. 9 specimens, AM W27061, Goss Passage, Beacon Island, 28°25.5'S 113°47.0'E, dead Acropora with sponges, ascidians, coralline algae, 32 m, P.A. Hutchings, 19 May 199. 6 specimens, AM W27062, 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. 3 specimens, AM W27063, 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. 10 specimens, AM W27064, 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. 1 specimen, AM W27065, Goss Passage, Beacon Island, 28°25.5'S 113°47.0'E, dead Acropora plates covered in coralline algae & sponges, 24 m, P.A. Hutchings, 21 May 1994. 2 specimens, AM W27066, 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. 5 specimens, AM W27067, 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. 4 specimens, AM W27068, southeast end of Long Island, 28°28.8'S 113°46.5'E, dead coral embedded in calcareous substrate, 30 m, P.A. Hutchings, 22 May 1994. 2 specimens, AM W27069, southeast end of Long Island, 28°28.8'S 113°46.5'E, dead coral substrate with coralline algae, 8 m, P.A. Hutchings, 22 May 1994. 12 specimens, AM W27070, Goss Passage, Beacon Island, 28°25.5'S 113°47.0'E, dead coral substrate embedded in fine sediment, 33 m, P.A. Hutchings, 23 May 1994. 2 specimens, AM W27071, 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. 6 specimens, AM W27072, northeast entrance to Goss Passage, Beacon Island, 28°27.9'S 113°46.7'E, dead branching Acropora substrate covered with algae, 24 m, P.A. Hutchings, 25 May 1994. 11 specimens,AM W27073, northeast entrance to Goss Passage, Beacon Island, 28°27.9'S 113°46.7'E, dead plate-like Acropora covered with coralline algae, 8 m, P.A. Hutchings, 25 May 1994. 3 specimens, AM W27074, 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. 2 specimens, AM W27075, 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. 5 specimens, AM W27076, East Montlivet Island, 15°06'S 125°18'E, 6 m, P.A. Hutchings, 16 July 1988. 1 specimen, AM W27077, Long Reef, 13°58'S 125°38'E, 25 m, P.A. Hutchings, 17 July 1988. 11 specimens, AM W27078, southwest corner of Lucas Island, 15°13'S 124°31'E, 30 m, P.A. Hutchings, 24 July 1988.4 specimens & 2 specimens on SEM stub, AM W27430, Lafontaine Island, Kimberley region, 14°10'S 125°47'E, 15 m, P.A. Hutchings, 19 July 1988. 3 specimens, AM W27432, Red Bluff, Kalbarri, 27°42'S 114°09'E, mixed coralline algae from rocky shore, 4 m, J.K. Lowry, 10 Jan 1984. 20 specimens, AM W27435, 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. 5 specimens, AM W27455, 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, 0.2 mm wide, 56 chaetigers. Prostomium ovate to subrectangular or subpentagonal, wider than long; 4 eyes in trapezoidal arrangement. Antennae inserted anterior to a line between anterior eyes, near anterior margin, all at same level (Figs. 75A, 76A); median antenna longer than lateral antennae, slightly longer than prostomium, shorter than prostomium and palps together, cylindrical with a distinct enlargement on middle and a subdistal narrowing; lateral antennae cylindrical, about 2 ⁄ of length of median antenna 3

(Fig. 75A). Palps broad, longer than prostomium, fused along their length, with a distinct dorsal furrow (Figs. 75A, 76A ). Peristomium similar in length to following segments; tentacular cirri ovoid, small. Dorsal cirri similar to tentacular cirri but longer, shorter than parapodial lobes, absent on chaetiger 2 (Figs. 75A, 76A ). Anterior 5 parapodia each with about 5 compound falcigers, with spinose shafts and short, bidentate blades, subdistal tooth long and minute, indistinct distal tooth, with straight, moderate marginal spines (Fig. 75B), 6–7 µm long, without compound spinigerlike chaetae. From about chaetiger 6, parapodia each with solitary spiniger-like chaeta, shaft enlarged, distally expanded, with numerous long spines, and proportionally short, thin, unidentate, triangular blade, appearing like a long spine under low magnifications, provided with a few thin marginal spines (Figs. 75D, 76B,C ); in addition 3 falcigers, similar to those of anteriormost parapodia but shorter (Figs. 75E, 76B ), about 5–6 µm long; posterior parapodia each with solitary compound spiniger-like chaetae (Fig. 75G) similar to those of midbody segments; in addition 2 falcigers, with short blades (Figs. 75H, 76D ), 4 µm long. Dorsal simple chaetae from chaetiger 1 or from an anteriormost parapodium, with rounded tips and finely spinulose subterminally (Figs. 75C, 76C ), thicker posteriorly (Fig. 75F). Ventral simple chaetae on posterior parapodia, thick, sigmoid, smooth, bidentate, with small distal tooth and large subdistal tooth (Figs. 75I, 76D ). Pharynx short, through about 3–4 segments; pharyngeal tooth small, on anterior rim (Fig. 75A). Proventricle short in relation to length of body, small, through 3 segments, with 14 muscle cell rows. Pygidium with 2 long anal cirri.

Remarks. Exogone (E.) heterosetosa and E. (E.) heterosetoides , only known from the Southern Hemiphere, both have modified spiniger-like chaetae, with distally enlarged and spinose shafts and relatively short, triangular blades. Recently, another species, E. (E.) mompasensis Martínez, Adarraga & San Martín (2002), with similar chaetae, has been discovered on the Atlantic Spanish coasts. This species differs from these two Southern species in the size of the median antenna, insertion of the antennae, size of the proventricle, and details of the chaetae (Martínez et al., 2002). San Martín (1991a) erroneously placed E. heterosetoides in the subgenus Parexogone .

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

Habitat. Common on all shallow bottoms: algae, sand, seagrass, dead corals, mud, etc; intertidal to 33 m depth.

Figures

Fig. 76. SEM of Exogone (Exogone) heterosetoides. (A) anterior end, dorsal view. (B) compound chaetae, midbody. (C) dorsal simple chaeta and shaft of spiniger-like chaeta. (D) chaetal bundle, posterior parapodium.