Prosphaerosyllis sexpapillata (Hartmann-Schröder, 1979)

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 : 66-67

Prosphaerosyllis sexpapillata (Hartmann-Schröder, 1979)

Figs. 20E–F, 21A–H

Sphaerosyllis sexpapillata Hartmann-Schröder, 1979: 105 , figs. 144–147; 1980a: 55; 1981: 37; 1982: 72; 1983: 135; 1984: 24; 1985: 72; 1986: 43; 1989: 30; 1990: 54.

Sphaerosyllis (Prosphaerosyllis) sexpapillata .–Hartmann-Schröder, 1987: 42.

Material examined. AUSTRALIA: TASMANIA. 6 specimens, AM W27672, north end of beach, Parsons Cove, Freycinet National Park, 42°08.6'S 148°16.9'E, coarse gravel, intertidal, 24 Jan 1986, N.W. Riser. WESTERN AUSTRALIA. 1 specimen, HZM P-17068, Rockingham, Point Peron, G. Hartmann-Schröder.

Description. Body small, up to 2.6 mm long, 0.55 mm wide, 25 chaetigers, broad anteriorly, provided with scattered, small dorsal and ventral papillae (Figs. 20E, 21A) on anterior segments; from proventricular level, each segment provided dorsally with 6 small papillae, arranged forming a “V”, 3 on each side of segment (Figs. 20E,F, 21B). Prostomium oval, longer than wide, nearly completely covered by peristomium; 4 large eyes in trapezoidal arrangement and 2 anterior eyespots. Antennae small, pyriform to sphaerical, all similar in shape and size (Figs. 20E, 21A), with bulbous bases and minute, indistinct tip; all antennae inserted in line, in front of eyespots (Fig. 21A). Palps large, short, totally fused all along their length, with a few papillae (Fig. 21A). Peristomium covering dorsally almost all prostomium; tentacular cirri similar in shape to antennae, but smaller (Figs. 20E, 21A). Dorsal cirri on all segments, similar to antennae anteriorly, appearing sphaerical (Fig. 21A) but provided with a short, small tip (Figs. 20E, 21C,D); from midbody posteriorly, dorsal cirri slightly elongate (Fig. 20F), with a distal, retractile tip and an internal, dark gland (Fig. 21E). Parapodial lobes relatively short. Compound chaetae heterogomph, with strong articulation, with smooth shafts, and unidentate, short blades, smooth (Fig. 21H). Anterior parapodia each with 7–8 compound chaetae, diminishing to 3–4 on posterior parapodia. All blades similar in size, 10–12 µm on anterior parapodia, slightly shorter on posterior parapodia. Dorsal simple chaetae from anterior segments, usually from chaetiger 1, unidentate, with few, short subdistal spines (Fig. 21F). Ventral simple chaetae on posterior parapodia, sigmoid, smooth (not seen in the examined specimen). Acicula solitary, acuminate (Fig. 21G). Pharynx wide, through 5 segments; pharyngeal tooth oval, located just posteriorly to middle of pharynx (Fig. 21A). Proventricle similar in length and width to pharynx, through 3 segments, with 18–20 muscle cell rows.

Remarks. This species is similar to P. longipapillata Hartmann-Schröder, 1979 and P. nathani San Martín & López, 1998, differing mainly in having small papillae, arranged forming a V on dorsum of each segment instead of rows of long papillae. Prosphaerosyllis pumila (Westheide, 1974) from Galápagos Islands is similar in having all the antennae inserted on anterior margin of prostomium, but the dorsal cirri are similar throughout, with longer tips than those of P. sexpapillata and the pharyngeal tooth is much smaller, located more anteriorly in the pharynx (Westheide, 1974).

One specimen from Tasmania, used for SEM photographs, agrees well with the above description, although the median antenna is missing and it is difficult to say if it is anterior or not on prostomium. That specimen is a mature female, carrying eggs dorsally. In the original description, the elongation of dorsal cirri from midbody was omitted, but it is present both in the examined specimen from HZM (P-17068) as well as in the specimen used for SEM examination.

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

Habitat. Amongst algae, sediments. Intertidal and shallow depths.