Trypanosyllis (Trypanobia) depressa ( Augener, 1913 )

Martín, Guillermo San, Hutchings, Pat & Aguado, María Teresa, 2010, Syllinae (Polychaeta: Syllidae) from Australia. Part 3. Genera Alcyonosyllis, Genus A, Parahaplosyllis, and Trypanosyllis (Trypanobia), Zootaxa 2493, pp. 35-48 : 43-45

Trypanosyllis (Trypanobia) depressa ( Augener, 1913)

( Fig. 5 )

Haplosyllis depressa Augener, 1913: 216 , pl. 3, figs 29, 30, text-fig. 27 a, b.

Trypanosyllis (Trypanobia) depressa Imajima, 1966: 242 , figs 46 a–f; 2003: 160.

Material examined. Holotype. AUSTRALIA: Western Australia, Shark Bay, 9 m, 16, June, 1905, W. Michaelsen and R Hartmeyer coll., H. Augener id., ZMH V- 7946.

Description. Holotype a complete specimen 1 mm wide, broken in three pieces, an anterior part 4.2 mm long, with 52 chaetigers, midbody part 2.3 mm long, with 29 chaetigers, and posterior part 4.4 mm long, with 62 chaetigers, plus an acephalous stolon 2.1 mm long, with 32 segments, (total length 13 mm, with 173 chaetigers) (Augener reported the holotype as being complete, 15 mm long with 170 segments). Body strongly dorso-ventrally flattened, ribbon-like ( Fig. 5 A), slightly convex ventrally, with numerous short and wide segments. Prostomium rounded, slightly bilobed both anteriorly and posteriorly, with two prostomial lobes. Four eyes in rectangular arrangement. Palps short, ventrally directed, completely separate. Antennae inserted on anterior margin of prostomium; median antenna inserted between anterior pair of eyes, with about 15 articles, lateral ones with about 12 articles, inserted on anterior margin of prostomium. Peristomium dorsally reduced, only visible laterally and ventrally; dorsal tentacular cirri longer than antennae, with about 20–22 articles; ventral tentacular cirri about half the length of dorsal ones. Cirrophores well developed; dorsal cirri relatively short and thick, lacking on numerous segments, with about 18–20 articles ( Fig. 5 A). Parapodia with digitiform pre- and postchaetal lobes. Ventral cirri digitiform. Chaetae similar throughout body, thick, sub-distally slightly enlarged, distally unidentate, with basal spur relatively long, distally directed ( Fig. 5 B). Anterior parapodia with 4–5 chaetae, decreasing to 2–3 on posterior parapodia. Acicula solitary on posterior parapodia, 2–3 on anterior ones, slender, straight. Pharynx relatively slender, through about 20 segments, with trepan of 10 teeth and a crown of 10 soft papillae. Proventricle similar in width to pharynx, slender, through about 18 segments, with about 38–40 muscle cell rows.

Remarks. The holotype has the pharynx partially dissected; the crown of papillae was visible, but not the trepan, which was described by Imajima (1966, 2003) as having 10 teeth. Habitat. Unknown, 9– 13 m.

Distribution. Australia (Western Australia). Japan.

Figures

FIGURE 5. Trypanosyllis (Trypanobia) depressa (Augener, 1913). HZM V- 7946. A, anterior end, dorsal view. B, chaetae. Scale. A: 0.4 mm. B: 40 Μm.