Erinaceusyllis perspicax Soto & Martín 2017, new combination

Erinaceusyllis perspicax (Ehlers, 1908) new combination

Figure 7

Sphaerosyllis perspicax Ehlers, 1908: 66, pl. 6, figs. 1–3; 1913: 480; Hartman 1964: 89, pl. 28, figs. 4–5.

Material examined. Station 36 (1) and station 41 (1) (LBUV).

Description. Body small, 2.8 mm long, 0.3 mm wide, 24 chaetigers, with numerous, scattered, short papillae on dorsum (Fig. 7A), slightly longer laterally, especially prominent on palps. Prostomium oval, slightly wider than long; with four large eyes in trapezoidal arrangement, nearly in line, and two anterior eyespots; antennae with bulbous bases and short tips; median antenna short, inserted on posterior margin of prostomium; lateral antennae similar to median antenna, inserted in front of anterior eyes. Palps shorter than prostomium, fused along their length, with numerous, distinct papillae (Fig. 7A). Peristomium covering dorsal posterior margin of prostomium; tentacular cirri similar to antennae. Dorsal cirri with bulbous bases and short tips, more elongated than antennae and tentacular cirri, absent on chaetiger 2 (Fig. 7A), more elongate in mid-body. Parapodia rectangular to conical, with few, small, papillae. Compound chaetae heterogomph, with smooth shafts (Figs 7 B, D); blades short, falcate, unidentate, all similar in length, about 18–20mm; margin of blades provided with long, slender spines (Figs 7B, D); anterior parapodia with 7–9 compound chaetae, decreasing in number posteriorly to 5–6 on posterior parapodia. Dorsal simple chaetae on posterior parapodia, unidentate, provided with minute marginal subdistal spines (Fig. 7C) or smooth. Ventral simple chaetae slender, smooth, unidentate (Fig. 7E), on far posterior parapodia. Acicula solitary, acuminate (Fig. 7F), with another slender, straight acicula on far anterior parapodia. Pharynx through five segments; pharyngeal tooth, slightly behind opening (Fig. 7A). Proventricle long, wide, barrel-shaped, through 3–4 segments, with about 20–22 muscle cell rows. Pygidium semi-circular, with two anal cirri similar to dorsal cirri.

Remarks. Erinaceusyllis perspicax is characterized by having large eyes distinctly in a line and separated. The antennae, tentacular and anterior dorsal cirri are inflated, with slender tips, becoming more elongated, and slightly inflated on bases, from mid-body. The compound chaetae are more or less elongated, with unidentate blades, and with moderate to long, straight spines on margin.

The most similar species is E. hartmannschroederae, San Martín, 2005 from Australia, but in that species the eyes are not so separated, the anterior appendages are not so inflated on bases, and the blades of compound chaetae are shorter, and similar in size, without spines on the ventral ones (San Martín 2005).

Distribution. Kerguelen Islands, Antarctica (Wilhelm II coast). Chilean Patagonia, first report to Chile.

Habitat. Shallow subtidal (30 m depth). Inside tubes of Chaetopterus cf. variopedatus in fjords and channels from Patagonia. Salinity: from 30.2 to 35 PSU, temperature: from 8.7 to 8.9°C.