Exogone (Parexogone) wolfi San Martín, 1991

Exogone (Parexogone) wolfi San Martín, 1991 View in CoL

Fig. 64A–J

Exogone (Parexogone) wolfi San Martín, 1991a: 726, fig. 6; San Martín et al., 1996: 252, fig. 3; San Martín, 2003: 243, figs. 129, 130.

Material examined. AUSTRALIA: WESTERN AUSTRALIA. 1 specimen, AM W27092, 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. 4 specimens,AM W27093, 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 W27094, northeast entrance to Goss Passage, Beacon Island, 28°27.9'S 113°46.7'E, dead plate-like Acropora covered in coralline algae, 8 m, P.A. Hutchings, 25 May 1994.

Description. Body long, slender, filiform, 8 mm long, 0.12 mm wide, 53 chaetigers. Prostomium nearly rounded; 2 pairs of small eyes in trapezoidal arrangement and 2 minute anterior eyespots. Median antenna inserted in front of line between posterior eyes, cylindrical, 1.5 times as long as combined length of prostomium and palps; lateral antennae much shorter than median antenna, slightly shorter than prostomium, inserted in front of anterior eyes (Fig. 64A). Palps longer than prostomium, completely fused all along their length, forming a triangular, acute piece. Peristomium similar to inmediately following segments, rectangular in shape; tentacular cirri minute, papilliform. Segments posterior to proventricle longer than wide (Fig. 64A). Dorsal cirri papilliform, elongate, shorter than parapodial lobes, present on all parapodia. Compound chaetae with smooth shafts or provided with long, thin subdistal spines, and including on each parapodium chaetae with elongate, spiniger-like, bidentate blades, both teeth small and similar (Fig. 64B,E), those of posterior parapodia with subdistal tooth slightly longer than distal one (Fig. 64K), provided with long, thin, erected marginal spines, those of distal part even longer, extending beyond tip, together with several falcigers, similar in shape to spiniger-like, but shorter (Figs. 64C,F,I). Anterior parapodia each with 1–2 spiniger-like chaetae, blades about 40 µm long (Fig. 64B), and about 10 falcigers (Fig. 64C) with dorsoventral gradation in length, 23 µm above, 12 µm below; progressively to midbody, blades longer; midbody parapodia each with 1 spiniger-like chaeta (Fig. 64E), blade about 54 µm long, and 5–6 falcigers (Fig. 64F), blades 24 µm above 14 µm below; posterior parapodia each with 1 spiniger-like chaeta much shorter than those of midbody (Fig. 64K), 28 µm long, and only 2– 3 falcigers, with subdistal tooth slightly longer than distal tooth (Fig. 64I), blades 12 µm above 9 µm below. Dorsal simple chaetae from midbody, distinctly bidentate, provided with several long marginal spines (aristae), extending beyond tip (Fig. 64D), thicker and more strongly bidentate on posterior parapodia (Fig. 64H). Ventral simple chaetae on posterior parapodia, strongly bidentate, subdistal tooth slightly longer than distal tooth, provided with moderately long, thin subdistal marginal spines (Fig. 63J). Acicula solitary, distally expanded and rounded (Fig. 64G). Pharynx long and slender, through about 4 segments; pharyngeal tooth on anterior rim (Fig. 64A). Proventricle short, through 1.5 segments, with about 17 muscle cell rows. Pygidium semi-circular, with 2 long anal cirri.

Remarks. The Australian specimens agree well with the previous descriptions, so I consider them as the same species, despite strong differences in habitat preference and wide distribution.

Distribution. USA (Florida and Gulf of México). Capbreton Canyon (Gulf of Biscay, between Spain and France). Eastern Mediterranean. Australia (Western Australia).

Habitat. Interstitial in sand, between 106 and 1,000 m depth. The Australian specimens have been collected in shallow waters, inside dead corals with other organisms.

Exogone (Parexogone) patriciae n.sp.

Fig. 65A–I

Material examined. AUSTRALIA: VICTORIA. HOLOTYPE: MV F62746, Eastern Bass Strait, 13.1 km E of eastern of Lake Tyers, 37°49.9'S 148°14'E, coarse sand, 21 m depth, 4 Jun 1991. PARATYPES: 9 specimens, MV F62118, Eastern Bass Strait, 5.7 km W of Cape Conran, 37°48.85'S 148°39.8'E, coarse sand, 22 m depth, 4 Jun 1991. PARATYPES: 12 specimens, MV F62757, Eastern Bass Strait, 13.1 km E of eastern Lake Tyers, 37°49.9'S 148°14'E, coarse sand, 21 m depth, Feb 1991. QUEENSLAND. 1 specimen,AM W26404, 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 W26405, Lizard Island, 14°40'S 145°28'E, C. Short & A.R. Jones, 1978. NEW SOUTH WALES. 1 specimen, AM W21625, south of airport runway extension, Botany Bay, 33°58.13'S 151°11.16'E, 5 m, Australian Museum party, 7 Apr 1992. 5 specimens, AM W21626, south of airport runway extension, Botany Bay, 33°58.13'S 151°11.16'E, 5 m, Australian Museum party, 7 Apr 1992. 2 specimens, AM W21627, south of airport runway extension, Botany Bay, 33°58.13'S 151°11.16'E, 5 m, Australian Museum party, 7 Apr 1992. 1 specimen, AM W26406, south of Worang Point, Twofold Bay, 37°03.5'S 149°56.5'E, benthic, 6.1 m, S. Keable, P. Albertson, 21 Feb 1985, E166. 1 specimen, AM W26522, south of airport runway extension, Botany Bay, 33°58.13'S 151°11.16'E, 5 m,Australian Museum party, 7 Apr 1992.

Description. Body long, slender, filiform, holotype 5.8 mm long, 0.1 mm wide, 59 chaetigers. Prostomium ovate, wider than long; 4 eyes in trapezoidal arrangement; median antennae long, about 2.5 times longer than combined length of prostomium and palps, cylindrical, inserted between posterior pair of eyes (Fig. 65A,C); lateral antennae similar in length to prostomium, inserted in front of anterior eyes. Palps broad, short, completely fused (Fig. 65A,C). Peristomium similar to following segments, covering posterior part of prostomium; tentacular cirri ovate, smaller than dorsal cirri; dorsal cirri on all parapodia, ovate, slightly shorter than parapodial lobes (Fig. 65A), elongate on posterior parapodia (Fig. 65B). Anterior parapodia each with 1–2 compound chaetae with long, spiniger-like, unidentate blade, provided with short, fine marginal spines, about 64 µm long, and 8–10 compound chaetae with bidentate falcigers, teeth similar, provided with moderately long marginal spines, slight dorsoventral gradation in length, 16.8 µm above, 12.4 µm below. Posteriorly spiniger-like chaetae are lost and chaetae with shorter blades replace them, the numbers of falcigers per parapodium decreasing to 5 in midbody; posterior parapodia each with 4 falcigers, blades short, subdistal tooth large, and distal tooth smaller, forming a wide angle between them; long marginal spines, erect, longer towards tips, extending beyond tip of subdistal tooth, blades 9 µm above, 8 µm below. Dorsal and ventral simple chaetae from chaetiger 26 in holotype, thick, strongly bidentate, with long, broad, triangular subdistal tooth much larger than distal tooth; dorsal simple chaetae provided with long subdistal spines, erect, longer than distal tooth. Ventral simple chaetae thick, sigmoid, subdistal spines reaching level of subdistal tooth. Acicula solitary, distally bent at right angle. Pharynx long, through about 3–4 segments, pharyngeal tooth on anterior rim. Proventricle short, through 3 segments, with 16–18 muscle cell rows. Pygidium rounded, with 2 long anal cirri (Fig. 65B).

Remarks. Exogone (Parexogone) patriciae n.sp. is characterized by its distinctly thick ventral simple chaetae; no other species of the genus has this kind of chaetae, except Exogone (P.) annamurrayae (see below), but that species lacks compound chaetae with spiniger-like blades, and the lateral antennae are longer.

Distribution. Australia (Victoria, New South Wales, Queensland).

Habitat. On coarse, medium and fine sand in moderate depths (about 20 m).

Etymology. The species is named in honour of Dr Patricia Hutchings, of The Australian Museum. This paper would be impossible without her encouragement, support and help.