Syllis karlae, Martín, Guillermo San, Álvarez-Campos, Patricia & Hutchings, Pat, 2017

Martín, Guillermo San, Álvarez-Campos, Patricia & Hutchings, Pat, 2017, The genus Syllis Savigny in Lamarck, 1818 (Annelida: Syllidae: Syllinae) from Australia (second part): four new species and re-description of twelve previously described species, Zootaxa 4237 (2), pp. 201-243 : 212-214

Syllis karlae n. sp.

Figure 6

Material examined. AUSTRALIA, WESTERN AUSTRALIA: Goss Passage, south east end of Long Island , 28° 28' 48" S, 113° 46' 30" E, holotype, AM W.48534, coll. 30 m, 22 May 1994 .

Description. Holotype complete specimen, 9.5 mm long, 0.25 mm wide, with 65 chaetigers. Body slender, elongated, filiform, without colour pattern. Prostomium pentagonal; 4 small eyes in open trapezoidal arrangement and 2 anterior eyespots. Palps similar in length to prostomium ( Fig. 6 A). Median antenna arising on middle of prostomium, with 10 articles, shorter than the combined length of prostomium and palps; lateral antennae slightly longer than the median one, with about 12 articles. Peristomium shorter than subsequent segments ( Fig. 6 A). Dorsal tentacular cirri longer than antennae, with about 13 articles; ventral tentacular cirri about half as long as dorsal ones, with 7 articles. All dorsal parapodial cirri short, similar in length to body width, with few articles, ( Fig. 6 A), anteriormost dorsal parapodial cirri with about 10–12 articles, 10–8 articles from midbody to posterior end. Vental parapodial cirri short, digitiform. Anterior parapodia with about 7 compound chaetae each, reducing to 5 compound chaetae on each posterior parapodium; on anterior parapodia, chaetae slender, elongated, blades with proximal tooth slightly longer than distal one, margin of blades smooth or with very short spines, blades 21 µm long above, 12 µm long below ( Fig. 6 B); chaetae becoming shorter after first chaetiger, all similar, with large, distally curved shafts and short, smooth blades, with long proximal tooth and short, acute distal tooth, blades about 12–10 µm long ( Fig. 6 D). Dorsal simple chaetae on posterior parapodia only, slender, smooth, distally bidentate ( Fig. 6 E). Ventral simple chaeta on far posterior segments only, smooth, bidentate, with proximal tooth larger than distal one ( Fig. 6 F). Anterior parapodia with 2 acuminate aciculae each, one of them subdistally inflated ( Fig. 6 C), single acicula per parapodium from midbody onwards, subdistally inflated, acuminate, larger than anterior ones ( Fig. 6 G). Pharynx extending through about 7 segments; pharyngeal tooth on anterior margin of pharynx ( Fig. 6 A). Proventricle through 4 segments, with about 30 muscle cell rows. Pygidium with 2 anal cirri, with 7 articles each, median stylus not observed.

Remarks. No previously described species of the genus Syllis is known to have similar compound chaetae, so it is described here as a new species, although there is only one specimen available.

Other species with unusual posterior compound chaetae with short blades are Syllis bifurcata (Hartmann- Schröder, 1980), from the West Indian and Caribbean Sea, S. bifida (Hartmann-Schröder, 1986) , from Subantarctic, and Syllis curticirris (Hartmann-Schröder, 1981) , from the Meteor Bank, central Atlantic. All these three species have different chaetae, with spines on margin of blades (see Licher, 1999) which are lacking in S. karlae , n. sp. Syllis bifurcata also has a strong subdistal spur on shafts of compound chaetae, which are absent in S. karlae , n. sp. Syllis bifida has the distal tooth of posterior blades very short and very close to proximal tooth; such teeth in S. karlae are not so small and clearly separated from proximal teeth. Finally, the posterior compound chaetae of S. curticirris has distal teeth thicker and shorter than those of S. karlae n. sp., and the proximal teeth are not as elongated as in S. karlae n.sp.

Etymology. The new species is named after Karla Paresque, colleague and friend, for her important contributions to the knowledge of the family Syllidae .

Habitat. Dead coral substrate.

Distribution. Australia (Western Australia).

Figures

FIGURE 6. Syllis karlae n. sp. (AM W. 48534). A, anterior end, dorsal view. B, compound chaetae, anterior parapodium. C, aciculae, anterior parapodium. D, compound chaetae, posterior parapodium. E, dorsal simple chaeta. F, ventral simple chaeta. G, acicula, posterior parapodium. Scale bars: A: 0.18 mm. B – G: 20 µm.