Sphaerosyllis bifurcatoides ( Hartmann-Schröder, 1979 ), 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 : 88

Sphaerosyllis bifurcatoides ( Hartmann-Schröder, 1979) n.comb.

Fig. 43A–J

Parapionosyllis bifurcatoides Hartmann-Schröder, 1979: 97 , figs. 112–118; 1991: 35.

Material examined. AUSTRALIA: VICTORIA. 14 specimens, MV F62748, Eastern Bass Strait, 11.7 km W of Pt. Ricardo, 37°49.90'S 148°30.01'E, 29 m depth, 28 Sept 1990. 2 specimens, MV F87426, off Werribee, Port Phillip Bay, 38°02.3'S 144°41.3'E, sand, 10 m depth, 10 Jun 1971. WESTERN AUSTRALIA.1 specimen, AM W26821, the Blow Holes, Point Quobba, 113°25'E 24°39'S, exposed intertidal rock shelf, short tufted clumps of brown algae, 7 Jan 1984.

Description. Body small, slender, 1.9 mm long, 0.15 mm wide, 32 chaetigers. Anterior segments with few, small dorsal papillae ( Fig. 43A ); from post-proventricular segments posteriorly, papillae numerous ( Fig. 43A,B ) covering dorsum, some papillae on parapodia; papillae long, distinct, with slender stalk and expanded, rounded or slightly trilobed tips ( Figs. 43A,B,G ), with dark inclusions. Papillae absent on prostomium and palps, scarce on peristomium and more anterior segments. Prostomium ovate to trapezoidal; 4 large eyes in trapezoidal arrangement. Antennae relatively long, with bulbous bases and long, slender tips, shorter than combined length of prostomium and palps ( Fig. 43A ) or similar in length. Palps short, broad, fused along their length. Peristomium similar in length to following segments, anterior margin slightly bilobed, covering posterior part of prostomium; tentacular cirri shorter than antennae, with bulbous bases and short, distally rounded tips. Dorsal cirri short, similar to tentacular cirri, slightly shorter than parapodial lobes, with bulbous bases and slender tips ( Fig. 43A,B ). Parapodial lobes rectangular, provided with 2 distal, rounded papillae ( Fig. 43A ). Ventral cirri relatively long, slender. Parapodial glands large, difficult to see, with granular material ( Figs. 43B ). Anterior parapodia each with 6–7 compound chaetae with unidentate, short blades; shafts more angular and thicker ventrally, with a subdistal spur ( Fig. 43E ); blades of dorsal compound chaetae with moderate, straight marginal spines, blades of ventral compound chaetae smooth, all blades similar in length, about 8 µm long. Number of compound chaetae on each parapodium diminishing posteriorly to 3 on posterior parapodia, with thick shafts provided with strong subdistal spur giving bifurcate appearance, and hooked blades, smooth or provided with short marginal spines ( Fig. 43J ), similar to those of anterior parapodia. Dorsal simple chaetae from anterior parapodia, unidentate, with few subdistal, irregular serrations on margin ( Fig. 43D,I ). Ventral simple chaetae present on posterior parapodia, sigmoid, unidentate, smooth ( Fig. 43K ). Solitary acicula with bent tip, forming right angle ( Fig. 43F,H ). Pygidium small, with a few rounded papillae and 2 anal cirri, longer than dorsal cirri ( Fig. 43C ). Pharynx through 3–4 segments; pharyngeal tooth conical, on anterior rim ( Fig. 43A ). Proventricle small, through 2 segments, with 15 muscle cell rows.

Distribution. Australia (Western Australia, Victoria, Queensland).

Habitat. Sand, coral sand, algae; intertidal to about 15 m depth.

Figures

Fig. 43. Sphaerosyllis bifurcatoides. (A) anterior end, dorsal view. (B) midbody segment, dorsal view. (C) posterior end, dorsal view. (D) dorsal simple chaeta, anterior parapodium. (E) compound chaetae, anterior parapodium. (F) acicula, anterior parapodium. (G) detail of papillae. (H) acicula, posterior parapodium. (I) dorsal simple chaeta, posterior parapodium. (J) compound chaetae, posterior parapodium. (K) ventral simple chaeta. Scale A–C: 70 µm, D–K: 20 µm.