Syllis parturiens Haswell, 1920

Martín, Guillermo San, Lucas, Yolanda & Hutchings, Pat, 2024, The genus Syllis Savigny in Lamarck, 1818 (Annelida: Syllidae: Syllinae) from Australia (Fourth part), Zootaxa 5453 (1), pp. 1-32 : 8-10

Syllis parturiens Haswell, 1920

Figure 5

Syllis (Typosyllis) parturiens Haswell, 1920: 97 , figs. 17, 18.— Ben-Eliahu 1977: 23, fig. 7.

Typosyllis parturiens .— Licher 1999: 89, fig. 42.

Material examined. AUSTRALIA, NEW SOUTH WALES: 50 m west of Split Solitary Island , 30° 14’ S, 153° 10’ 48” E, coll, P. A. Hutchings & C. L. Rose, 7 Mar 1992, on Herdmania momus , rocks, sponges and ascidians, 16 m, G. San Martín id., AM W.54884, 1 specimen . WESTERN AUSTRALIA: Houtman Abrolhos Islands, Goss Passage, southeast end of Long Island , 28° 28’ 48” S, 113° 46’ 30” E, coll. P. A. Hutchings, 22 May 1994, dead coral covered in coralline algae, 8 m, G. San Martin id., AM W.54885, 1 specimen .

Description. Both specimens of small size, incomplete, somewhat damaged; 4.1 mm, 42 chaetigers long, 0.3 mm wide, 35 chaetigers. Several appendages lost or broken. Without colour markings. Prostomium sub-circular, with two pairs of small eyes in open trapezoidal arrangement; median antenna lost, lateral antennae with about 13 articles, similar in length to prostomium and palps together; palps similar in length to prostomium ( Fig. 5A ). Peristomium shorter than subsequent segments; dorsal tentacular cirri with 15 articles, ventral ones with 12. Dorsal cirri slender, alternating in midbody long and short; long dorsal cirri with 19 articles, short ones with about 15 ( Fig. 5B ). Compound chaetae bidentate falcigers, proximal teeth smaller than distal ones, and moderately long spines on margin, straight or slightly curved distally, longer on basal half of margin, and a dorso-ventral gradation in length of blades ( Fig. 5C, D ); anterior parapodia with about seven falcigers, blades 32 µm long above, 22 µm below; posterior parapodia with five chaetae, blades 25 µm long above, 17 µm below. Anterior and midbody parapodia each with two aciculae, one distally acuminate and other distally broad ( Fig. 5E, F ); posterior parapodia with single acicula, distally acuminate ( Fig. 5G ). Dorsal and ventral simple chaetae not seen. Pharynx partially everted, long, with 47 muscle cell rows; pharyngeal tooth located on segments 5–6.

Remarks. This is a small species, only previously known by a single specimen (holotype) from NSW, and 49 specimens from the Red Sea ( Ben-Eliahu 1977); our specimens agree quite well with the Licher (1999) ’s redescription of the holotype, although the NSW specimen has apparently a longer proventricle, with more cell rows; the WA specimen has pharynx and proventricle of similar size than the holotype, but the dorsal cirri are shorter and thicker.

The most distinctive character of this species is its reproduction, being viviparous; however, none of our specimens have any sign of reproduction nor juveniles inside the body.

Habitat. Associated with ascidians and algae.

Distribution. Australia (NSW, WA), Red Sea (Gulf of Eilat).

Figures

FIGURE 5. Syllis parturiens Haswell, 1920. A, anterior end, dorsal view. B, long and short midbody dorsal cirri. C, compound chaetae, anterior parapodium. D, compound chaetae, posterior parapodium. E, aciculae, anterior parapodium. F, aciculae, midbody parapodium. G, acicula, posterior parapodium. AM W.54884. Scale. A: 0.2 mm. B: 0.1 mm. C-G: 20 µm.