Exogone (Parexogone) exmouthensis Hartmann-Schröder, 1980

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 : 109-111

Exogone (Parexogone) exmouthensis Hartmann-Schröder, 1980

Figs. 62A–G, 69E

Exogone exmouthensis Hartmann-Schröder, 1980a: 57 , figs. 45, 46; 1992a: 60, figs. 18–20.

Not Exogone (Parexogone) exmouthensis .–San Martín, 1991a: 726.

Material examined. AUSTRALIA: SOUTH AUSTRALIA. 2 specimens, AM W26633, Fifth Creek, Port Pirie, Spencer Gulf, 33°12'S 137°55'E, Posidonia in subtidal region, 2.8 m, T.J. Ward, Mar 1980. 1 specimen, AM W26661, off Fifth Creek, Port Pirie, Spencer Gulf, 33°12'S 137°55'E, Posidonia & Amphibolus spp. in subtidal region, 4.6 m, T.J. Ward, Aug 1979. WESTERN AUSTRALIA. 1 specimen, AM W27022, Goss Passage, Beacon Island, 28°25.5'S 113°47.0'E, dead plates of Acropora covered in coralline algae, 20 m, P.A. Hutchings, 20 May 1994. 2 specimens, AM W27023, southeast end of Long Island, Beacon 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 W27024, East Montalivet Island, 15°06'S 125°18'E, 6 m, P.A. Hutchings, 16 July 1988. 3 specimens, AM W27427, inshore reef off Ned’s Camp, Cape Range National Park, 21°59'S 113°59'E, frilly Caulerpa sp. , 1 m, J.K. Lowry, 2 Jan 1984. 1 specimen, and 2 specimens on SEM stub, AM W27439, 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 W27451, Lafontaine Island, Kimberley region, 14°10'S 125°47'E, 15 m, P.A. Hutchings, 19 July 1988. 3 specimens, and 1 specimen on SEM stub, AM W27458, limestone reef, off Ned’s camp, Cape Range National Park, 21°59'S 113°55'E, sponge with epiphytic algae, and muddy worm tubes, 1.5 m, R.T. Springthorpe, 2 Jan 1984. 1 specimen, AM W27461, 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 W27463, 5 km offshore, Bush Bay, 30 km south of Carnarvon, 25°10'S 113°39'E, airlift in strap-leaved seagrass beds, 2 m, J.K. Lowry and R.T. Springthorpe, 6 Jan 1984.

Exogone (Parexogone) penelopeae n.sp.

Fig. 63A–L

Material examined. AUSTRALIA: SOUTH AUSTRALIA. HOLOTYPE: AM W26410, Elliston Reef, 33°39'S 134°53'E, algae, P.A. Hutchings, 11 Mar 1979. NEW SOUTH WALES. PARATYPES: 2 specimens, AM W26411, northern side of Bannister Head, 35°19.15'S 150°29.12'E, grey sponge from top of boulder, 18 m, K. Attwood, 6 May 1997.

Description. Body long and slender, filiform, 6.4 mm long, 0.4 mm wide, about 74 chaetigers. Prostomium ovate, wider than long, with 4 small eyes in trapezoidal arrangement and, sometimes, 2 minute anterior eyespots; antennae papilliform, sphaerical, minute; median antenna slightly larger than lateral antennae, inserted between posterior eyes, lateral antennae inserted in front of anterior eyes. Palps long and broad, dorsally fused except for a distal deep notch (Fig. 62A, 69E). Peristomium covered by chaetiger 1 dorsally; tentacular cirri egg-shaped, larger than antennae. Dorsal cirri on all parapodia, similar to tentacular cirri (Figs. 62A, 69E).

Compound chaetae with strongly heterogomph, smooth shafts and short, triangular blades, provided with short subdistal tooth and moderately long marginal spines, longer on dorsalmost compound chaetae (Fig. 62C,E); anterior parapodia each with about 7 compound chaetae, all blades similar in length, about 14–11 µm; number of compound chaetae decreasing posteriorly to 4 per posterior parapodia, similar in shape to anterior ones, but with shorter blades, about 10 µm long. Dorsal simple chaetae from segments posterior to proventricle, smooth, strongly bidentate (Fig. 62F). Ventral simple chaetae on far posterior parapodia of some specimens, sigmoid, with short subdistal marginal spines, bidentate (Fig. 62G). Acicula solitary, distally expanded and rounded (Fig. 62D). Pygidium small, with 2 spherical anal cirri, similar to dorsal cirri but larger (Fig. 62B). Pharynx long, through about 7 segments; pharyngeal tooth on anterior rim (Fig. 62A). Proventricle long and slender, similar in length to pharynx, through about 8 segments, with 30 muscle cell rows.

Distribution. Australia (Western Australia, South Australia). Polynesia.

Habitat. Amongst algae, corals, seagrass, sand. Intertidal to about 30 m depth.

Description. Body cylindrical, moderately long, holotype incomplete, 4 mm long, 0.31 mm wide, 46 chaetigers. Prostomium ovate to sub-pentagonal, wider than long; 4 large eyes in trapezoidal arrangement; median antenna inserted between posterior eyes, thick, cylindrical, similar in length to prostomium and palps together or slightly shorter; lateral antennae egg-shaped, ovate, much shorter than median antenna, inserted in front of anterior eyes. Palps broad, slightly longer than prostomium, fused along their length, with a small dorsal distal furrow (Fig. 63A). Peristomium slightly shorter than following segments, covering dorsally posterior part of prostomium; tentacular cirri similar to lateral antennae but much smaller. Dorsal cirri on all segments, egg-shaped, larger than tentacular cirri but smaller than lateral antennae, shorter than parapodial lobes (Fig. 63A). Compound chaetae including 2–4 on anterior parapodia, 1–2 in midbody and posterior parapodia, spiniger-like with elongate blades, bidentate, both teeth small and similar, and long, erect, fine marginal spines, distal spines longer than remaining, extending beyond tips of blades, blades 39 µm long on anterior parapodia (Fig. 63B), 36 µm on midbody (Fig. 63F), 26–23 µm on posterior parapodia (Fig. 63J), in addition with several falcigers, 8 on anterior parapodia, 4–5 on midbody, 3–4 on posterior parapodia, with strongly bidentate blades, provided with long, erect marginal spines, longer on distal part, extending beyond tip, more strongly bidentate, with longer and thicker subdistal tooth posteriorly (Figs. 63C,G,K), slight dorsoventral gradation in length of blades on anterior parapodia, 18 µm above, 10 µm below, and all similar in length on remaining parapodia, about 16 µm on midbody, 12 µm on posterior parapodia. Dorsal simple chaetae from post-proventricular parapodia, bidentate, distal tooth small subdistal tooth long, provided with 6–7 thin, long, erect, spines (aristae) (Fig. 63H), disposed on a transverse inferior ridge (Fig. 63I). Ventral simple chaetae from about chaetiger 28 in holotype, sigmoid, similar to dorsal simple chaetae, but thicker, major difference in size of teeth, with only 2 aristae, proportionally shorter than those of dorsal simple chaetae (Fig. 63L). Anterior parapodia each with 2 aciculae, one straight and one bent laterally (Fig. 63D); remaining parapodia each with solitary acicula, distally expanded and rounded (Fig. 63E). Pharynx moderate in length, through about 5–6 segments; pharyngeal tooth conical, on anterior rim (Fig. 63A). Proventricle short, through 3 segments, with 17 muscle cell rows.

Remarks. This species is characterized by having several aristae on dorsal and ventral simple chaetae, compound chaetae with strongly bidentate blades, provided with long spines and subdistal tooth slightly longer than distal tooth, as well as short, egg-shaped lateral antennae and relatively short median antenna; no other species has these combinations of characters.

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

Habitat. On sponges and algal washings, up to 18 m depth.

Etymology. The species is named in honour of Dr Penelope (Penny) Berents, of The Australian Museum.