Exogone (Exogone) naidina Örsted, 1845

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 : 130-131

Exogone (Exogone) naidina Örsted, 1845

Fig. 79A–J

Exogone naidina Örsted, 1845: 20 , Figs. 1–14 ; Hartmann-Schröder, 1971: 171, figs. 56 a–c; 1979: 108, fig. 163; 1980a: 56; 1981: 38; 1982: 74; 1984: 25; 1986: 45; Gardiner, 1976: 132, figs. 11j–n; San Martín, 1984a: 208, pl. 46.

Exogone (Exogone) naidina San Martín, 2003: 262, figs. 142, 143.

Exogone gemmifera.–Fauvel, 1923: 305, figs. 117a–d; Day, 1967: 274, figs. 12.10. p–v; Ben-Eliahu, 1977: 78, fig. 7.

Material examined. AUSTRALIA: WESTERN AUSTRALIA. 1 specimen, AM W27643, 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 small, elongate, slender, 3 mm long, 0.2 mm wide, 28–30 chaetigers; anterior segments slightly enlarged. Prostomium semi-circular to oval; 4 thick eyes in trapezoidal arrangement. Antennae originating anteriorly in a line between anterior eyes, well separated; median antenna longer than lateral antennae and inserted slightly in front of them, shorter than combined length of prostomium and palps, cylindrical; lateral antennae inserted close to anterior eyes, similar to median antenna but distinctly shorter (Fig. 79A). Palps relatively short, fused along their length, with a distal notch. Peristomium similar to following segments in length; tentacular cirri minute, papilliform. Dorsal cirri similar to tentacular cirri but longer, distinctly shorter than lateral antennae, absent on chaetiger 2 (Fig. 79A). Parapodia of anteriormost 3 segments, each with 4–5 compound chaetae with spinose shafts and short, unidentate blades, about 6 µm, each provided with a long basal spur, making them appear bifid (Fig. 79C). Parapodia from chaetiger 4 each with 1 compound chaetae with unidentate, spiniger-like blade, short marginal spines (Fig. 79E), about 14 µm long, and 3 compound falcigers, shafts provided with subdistal and distal spines, and short blades, with long subdistal teeth and short distal teeth (Fig. 79F), about 5 µm long; posterior parapodia each with one spinigerlike, similar to those of anterior parapodia and midbody, but provided with shorter, smooth blade (Fig. 79G), about 11 µm long, and 2 compound falcigers with short, smooth blades (Fig. 79H). Dorsal simple chaetae from anterior parapodia, with rounded tips and finely spinulose subterminally (Fig. 79B), thicker posteriorly (Fig. 79I). Ventral simple chaetae on posterior parapodia, sigmoid, bidentate, subdistal tooth long and distal tooth short, with few, short subdistal marginal spines (Fig. 79J). Acicula solitary, slender, distally rounded (Fig. 79D). Pygidium with 2 long anal cirri. Pharynx long and slender, through 3 segments; pharyngeal tooth on anterior rim (Fig. 79A). Proventricle short, through 1–2 segments, with 14–16 muscle cell rows.

Remarks. This species is apparently cosmopolitan in temperate and tropical waters. In Australia it has been reported all around, but perhaps some of these reports could be referred to other similar species. Exogone (Exogone) dwisula Kudenov & Harris, 1995 , from California, is similar, but the proventricle is longer, through 1.5–2 segments (Kudenov & Harris, 1995).

Distribution. Cosmopolitan. Australia (all States).

Habitat. Shallow waters, on algae, fine to coarse sand, seagrasses.

Figures

Fig. 1. Nooralia bulgannabooyanga. (A) anterior end, dorsal view, holotype (antennae missing). (B) anterior end, dorsal view, a paratype (median antenna missing). (C) alternative dorsal cirri, midbody, holotype. (D) posterior end, dorsal view, a paratype. Scale 0.09 mm.

Fig. 2. Nooralia bulgannabooyanga. (A) anterior end, ventral view, holotype. (B) compound chaetae, chaetiger 1. (C) dorsal simple chaeta, midbody. (D) compound chaetae, midbody.(E) dorsal simple chaeta, posterior parapodium. (F) compound chaetae, posterior parapodium. (G) acicula. Scale A: 0.09 mm, B–G: 28 µm.

Fig. 3. SEM of Nooralia bulgannabooyanga, female carrying dorsally eggs. (A) anterior end, dorsal view. (B) detail of an egg. (C) the same.(D) detail of notochaetae.(E) dorsalmost compound neurochaeta. (F) ventralmost compound neurochaeta (midbody).

Fig. 4. Salvatoria kerguelensis (Australian specimens). (A) anterior end, dorsal view. (B) compound chaetae, anterior parapodium. (C) acicula, anterior parapodium. (D) dorsal simple chaeta. (E) compound chaetae, posterior parapodium. (F) ventral simple chaeta. (G) acicula, posterior parapodium. Scale A: 0.16 mm, B–G: 28 µm.

Fig. 5. SEM of Salvatoria kerguelensis (Australian specimens). (A) complete female carrying eggs. (B) anterior end, dorsal view. (C) detail of left nuchal organ. (D) capillary notochaetae supporting an egg. (E) dorsal compound chaeta, anterior parapodium. (F) mid compound chaetae, midbody parapodium.