Prosphaerosyllis isabellae (Nogueira, San Martín & Amaral, 2001)

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 : 68-69

Prosphaerosyllis isabellae (Nogueira, San Martín & Amaral, 2001) n.comb.

Fig. 23A–E

Sphaerosyllis isabellae Nogueira et al., 2001: 1777, fig. 1. Sphaerosyllis magnoculata Not Hartmann-Schröder, 1986.

Hartmann-Schröder, 1989: 29, fig. 37.

Material examined. AUSTRALIA: WESTERN AUSTRALIA. 1 specimen, AM W26620, 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 W26621, south east end of Long Island, Goss Passage, 28°28.8'S 113°46.5'E, dead coral substrate, embedded in calcareous substrate, 30 m, P.A. Hutchings, 22 May 1994.

Description. Body short, relatively slender, dorsal and ventral surfaces with small, scattered papillae, 3 mm long, 0.15 mm wide, 33 chaetigers. Prostomium rectangular to oval; 2 pairs of small eyes in rectangular arrangement close to each other on each side, and 2 anterior, small ocular eyespots. Antennae short, with bulbous bases and short, rounded tips (Fig. 23A); lateral antennae inserted on anterior margin of prostomium, just behind eyespots; median antenna inserted on posterior margin. Palps completely fused to each other, with a dorsal furrow, shorter than prostomium, densely covered by short papillae (Fig. 23A). Peristomium large, covering dorsally posterior part of prostomium; tentacular cirri similar to antennae but even smaller (Fig. 23A). Dorsal cirri on all segments, small, mammiform, with an oval subdistal part and short, buttonlike, retractile tip (Fig. 23A). Parapodia conical, short, provided with few, small papillae. Anterior parapodia each with about 6–7 compound chaetae, strongly heterogomph, smooth shafts, with short, unidentate, slightly hooked blades, provided with short marginal spines; numbers of compound chaetae decreasing posteriorly to 2–4; from proventricular segments all compound chaetae with smooth, hooked blades (Fig. 23C), 9–6 µm long. Dorsal simple chaetae from chaetiger 1, unidentate, with few, short subdistal spines (Fig. 23B). Ventral simple chaetae on posterior parapodia, similar to dorsal simple chaeta, smooth (Fig. 23D). Acicula solitary, acuminate (Fig. 23E). Pharynx long, everted on both specimens, through about 5 segments; pharyngeal tooth small, located on anterior 1 ⁄ 3; proventricle long and large, through 3–4 segments, with about 35–40 muscle cell rows.

Remarks. The Australian specimens of this species agree well with the original description, although the long distance between Brazil and Australia, so I assume that they belong to the same species. Prosphaerosyllis palpopapillata Hartmann-Schröder, 1992c, from Antarctica, is similar, but has longer antennae and dorsal cirri and a much shorter pharynx (Hartmann-Schröder, 1992c).

Distribution. Brazil (São Paulo). Australia (WA, Tasmania).

Habitat. On corals and calcareous substrates, from 4 to 30 m depth.