Syllis erikae (Hartmann-Schröder, 1981) Hartmann-Schroder, 1981

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 : 208-210

Syllis erikae (Hartmann-Schröder, 1981) , n. comb.

Figure 4

Typosyllis (Typosyllis) erikae Hartmann-Schröder, 1981: 27 , figs 28–31; 1983: 127. Typosyllis erikae . Licher 1999: 149, figs 66 D–F.

Material examined. AUSTRALIA, WESTERN AUSTRALIA: Kimberley, St. 58, Long Reef, 13° 58' S, 125° 38' E, AM W.48527 , 1 specimen, coll. P. Hutchings; St. 54 Condillac Island, 14° 6' S, 125° 33' E, AM W.48532 , 1 specimen, coll. P. Hutchings, 16 July 1988; Houtman Abrolhos, WA 517, Off Beacon Island, Goss Passage , 28° 25' 30" S, 113° 47' E, AM W.48528 , 3 specimens coll. 21 May 1994, 24 m; WA 518, Beacon Island, Goss Passage , 28° 25' 30" S, 113° 47' E, AM W.48529 , 13 specimens, coll. 8 m, 22 May 1994. WA 525, NE end Long Island, Goss Passage, 8 m, 22 May 1994, AM W29488. 1 specimen; WA 522, N end of Long Island, Goss Passage , 28° 27' 54" S, 113° 46' 18" E, AM W.29486 , 1 specimen, coll. 22 May 1994; WA 539, off south end of Long Island, Beacon Island , 28° 28' 48" S, 113° 46' 18" E, AM W.48530 , 2 specimens, coll. 4–5 m, 25 May 1994; WA 511, Goss Passage , Beacon Island, 28° 25' 30" S, 113° 47' E, AM W.48531 , 1 specimen (developing stolon), coll. 10 m, 18 May 1994.

Comparative material. Typosyllis gerlachi Hartmann-Schröder, 1960 . Sarso , Red Sea, Holotype. HZM P- 13877.

Description. Longest complete specimen 7 mm long, 0.23 mm wide, with 75 chaetigers (17 of which are of a developing stolon); some incomplete specimens even longer, up to 10 mm long. Body small, delicate, long and slender, filiform, without colour pattern; relaxed specimens with midbody and posterior segments marked and well separated from anterior and posterior ones. Prostomium oval; 4 small eyes in trapezoidal arrangement. Palps similar in length to prostomium ( Fig. 4 A). Median antenna arising between posterior eyes of prostomium, with 12 to 20–22 articles, distinctly longer than combined length of prostomium and palps; lateral antennae about half length of median one, with 12 articles. Peristomium shorter than subsequent segments ( Fig. 4 A). Dorsal tentacular cirri similar in length to lateral antennae, with about 14 articles; ventral tentacular cirri about 2/3 as long as dorsal ones, with 8 articles. Dorsal parapodial cirri similar in width on bases and tips, similar in length to body width, except for those of chaetigers 6 and 9, and with sphaerical, small, hyaline inclusions in some articles ( Fig. 4 A, B). Dorsal parapodial cirri of chaetiger 1 distinctly longer than subsequent ones, longer than body width, similar in length to median antenna, with 17–20 articles ( Fig. 4 A). Subsequent anterior dorsal parapodial cirri, with about 10 articles, longer ones with 13–15; segments after proventricle with dorsal cirri slightly alternating long (about 12 articles) and short (about 10). Parapodia conical, with a small, distal, rounded papilla ( Fig. 4 H). Ventral parapodial cirri digitiform, shorter than parapodial lobes. Compound chaetae heterogomph falcigers, relatively short, bidentate with both teeth well separated, similar in size or proximal tooth slightly smaller than distal one, with short, straight spines on margin, similar throughout body, but slightly longer and slender anteriorly ( Fig. 4 C, D, E). Anterior parapodia each with 7–8 compound chaetae, blades 22 µm long above, 15 µm long below ( Fig. 4 C); midbody parapodia with 4-6 compound chaetae each, blades 20 µm long above, 10 µm long below ( Fig. 4 D); posterior parapodia with 3–5 compound chaetae each, similar to those of midbody ( Fig. 4 E). Dorsal simple chaetae on posterior parapodia, distally truncate ( Fig. 4 F). Ventral simple chaetae on posterior segments, sigmoid, bidentate, with short, straight subdistal spines ( Fig. 4 G). Acicula solitary, distally bent at a right angle ( Fig. 4 H, I, J). Pharynx slender, extending through about 6–16 segments (depending on the degree of contraction); pharyngeal tooth on anterior margin of pharynx ( Fig. 4 A). Proventricle distinctly shorter than pharynx, through 2–3 segments, with about 25–30 muscle cell rows. Pygidium with 2 anal cirri, with 8–10 articles, and median stylus.

Remarks. This species is characterized by its small size, with high capacity of contraction, very slender and filiform body (in well relaxed specimens), presence of numerous, sphaerical, hyaline inclusions in articles of dorsal cirri, a long, slender pharynx, with a short proventricle; and for the foot-like aciculae, and truncate dorsal simple chaetae.

Contracted specimens are much shorter, with shorter segments, laterally rounded.

In the original description, Hartmann-Schröder (1981) pointed out that the holotype has a developing stolon, which she named as Chaetosyllis ; however, her description of the stolon reveals that it has two palps and two antennae, which clearly correspond to a Tetracerous stolon, not the Dicerous one (also known as Chaetosyllis ).

This species seems to be identical or very similar to Syllis truncata cryptica Ben-Eliahu, 1977 , from the Red Sea, also widely reported in warm areas of the Mediterranean Sea (San Martín 2003), which was synonymized by Licher (1999) with Typosyllis gerlachi Hartmann-Schröder, 1960 . The type of that species shows a thicker posterior aciculae, distally oblique, not slender and “foot-like” as in S. erikae and S. truncata cryptica .

Examination of the holotype of Typosyllis gerlachi showed a different kind of aciculae and dorsal simple chaetae, as well as differences in details of the compound chaetae, compared to specimens of Syllis truncata cryptica from the Mediterranean. So, we consider that the synonymy is not correct and they are different and valid taxa.

Syllis truncata Haswell, 1920 is quite similar to Syllis erikae ; however, the proventricle is longer (through 4–6 segments) and the pharynx opening is located more posteriorly in the first ( Haswell 1920b).

Habitat. Dead coral substrate in shallow waters.

Distribution. Australia (Western Australia).

Figures

FIGURE 4. Syllis erikae (Hartmann-Schröder, 1981) n. comb. (AM W. 29486). A, anterior end, dorsal view. B, long and short dorsal cirri, midbody parapodia. C, compound chaetae, anterior parapodium. D, compound chaetae, midbody parapodium. E, compound chaetae, posterior parapodium. F, dorsal simple chaeta. G, ventral simple chaeta. H, acicula, with distal part of parapodial lobe, anterior parapodium. I, acicula, midbody parapodium. J, acicula, posterior parapodium. Scale bars: A, B: 0.1 mm. C – J: 20 µm.