Erinaceusyllis bidentata (Hartmann-Schröder, 1974), Guillermo San Martin, 2005

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 : 77

Erinaceusyllis bidentata (Hartmann-Schröder, 1974) n.comb.

Fig. 31A–F

Sphaerosyllis erinaceus bidentata Hartmann-Schröder, 1974a: 134 , pl. 13, figs. 116–119; 1992b: 227, figs. 16–18.

Material examined. AUSTRALIA: WESTERN AUSTRALIA. 1 specimen, AM W26723, north end of Long Island, Goss Passage, 28°27.9'S 113°46.3'E, dead coral covered in coralline algae & brown algae, 6 m, C. Bryce, 22 May 1994. 1 specimen, AM W27642, north end of beach, Bundegi Reef, Exmouth Gulf, 21°49'S 114°11'E, rocky rubble, brown algae with epiphytes, 2 m, H.E. Stoddart, 4 Jan 1984.

Description. Body small to minute, 1.3 mm long, 0.14 mm wide, 24 chaetigers (incomplete specimen), covered with small, scattered papillae, more conspicuous on lateral margins of segments, also some papillae on dorsal cirri (Fig. 31A). Prostomium oval, wider than long; 4 large eyes nearly in line, and 2 anterior eyespots; antennae spindle-shaped with bulbous bases, shorter than combined length of prostomium and palps together, median antenna inserted slightly anterior to eyes; lateral antennae inserted on anterior margin, near eyespots. Palps similar in length to prostomium, fused along their length. Peristomium similar in length to following segments, covering dorsally posterior margin of prostomium, frontally slightly excavate (Fig. 31A); tentacular cirri similar to antennae but smaller. Dorsal cirri similar to antennae, longer than tentacular cirri, with bulbous bases and slightly elongated tip, absent on chaetiger 2 (Fig. 31A). Compound chaetae heterogomph, similar throughout; blades distinctly bidentate, margin provided with moderate-sized erect spines on bases of longer blades (Fig. 31B,F), short marginal spines of short blades (Fig. 31B,F); dorsoventral gradation in length, 26–12 µm on midbody. Dorsal simple chaetae from anterior parapodia, unidentate, smooth (Fig. 31C). Ventral simple chaetae slender, smooth, unidentate (Fig. 31E), present on posterior parapodia. Acicula solitary, acuminate (Fig. 31D). Pharynx proportionally long and slender, through 4 segments; pharyngeal tooth located slightly posterior to opening (Fig. 31A). Proventricle long and wide, barrel-shaped, through 3 segments, with about 20 muscle cell rows.

Remarks. This species is characterized by having all the compound chaetae bidentate and the anterior position of the median antenna. The previous descriptions show similar compound chaetae; the longer blades, however, are more slender and elongated. Erinaceusyllis cryptica (Ben-Eliahu, 1977) and Erinaceusyllis bilobata (Perkins, 1981) also have all compound chaetae with bidentate blades, but the median antenna is inserted more posteriorly (Ben-Eliahu, 1977; San Martín, 2003; Perkins, 1981; Russell, 1991). Erinaceusyllis parvoculata (Russell, 1989) has also similar compound chaetae, but the arrangement of eyes is distinctly different and the median antenna is inserted much more posteriorly (Russell, 1989).

Distribution. Eastern Africa (Mozambique). Australia (Western Australia).

Habitat. Sand, mixed bottoms (sand, algae, detritus, dead coral), shallow depth.