Syllis busseltonensis ( Hartmann-Schröder, 1982 ) Martín & Lucas & Hutchings, 2023

Martín, Guillermo San, Lucas, Yolanda & Hutchings, Pat, 2023, The genus Syllis Savigny in Lamarck, 1881 (Annelida: Syllidae: Syllinae) from Australia (Part 3): new species and redescription of previously described species, Zootaxa 5230 (3), pp. 251-295 : 259-261

Syllis busseltonensis ( Hartmann-Schröder, 1982) , n. comb.

Figure 4

Typosyllis (Typosyllis) busseltonensis Hartmann-Schröder, 1982: 62 , Figs 31–35; 1983: 127; 1984: 14; 1987: 33; 1989: 19; 1990: 46; 1992: 56.

Typosyllis busseltonensis .— Licher, 1999: 125, fig. 65 D–F.

Material examined. AUSTRALIA, NEW SOUTH WALES: Golf Course bommie, 500 m north-east of Ulladulla Head , 35° 20’ 29” S, 150° 29’ 12” E, coll. 2 May 1997, 15 m, gravel at base of boulders , AM W.3926, 1 specimen . Broughton Island, Esmeralda Cove , 32° 37’ 12” S, 152° 19’ E, coll. 11 May 1978, coll. P. Hutchings, St. 2818 , NSW Fisheries , kelp holdfast , AM W.53912, 2 specimens . NSW 680 , Split Solitary Island , 15–17 m, 7 March 1992 , AM W.29504, 1 specimen . SOUTH AUSTRALIA: Pondalowie and Marion Bays, Yorke Peninsula , 35° 14’ S, 136° 50’ E, coll. I. Loch, 22 Feb 1985, 0–3 m, Caulerpa and green algae , AM W.53913, 3 specimens . WESTERN AUSTRALIA: WA 362 , Cape Range National Park, inshore limestone reef off Neds Camp , 21° 59’ S, 113° 55’ E, coll. 2 Jan 1984, 1 m, frilly Caulerpa, AM W. 53910, 2 specimens . WA 391 , Exmouth Gulf, beach at north end of Bundegi Reef , 21° 49’ S, 114° 11’ E, coll. 4 Jan 1984, 1–2 m, rocky rubble, coralline algae with green epiphyte , AM W.53906, 4 specimens . WA 392 , Exmouth Gulf, beach at north end of Bundegi Reef , 21° 49’ S, 114° 11’ E, coll. 4 Jan 1984, 1–2 m, coral rubble, brown alga with epiphytic growth, sticky sediment , AM W.53882, 17 specimens .

Diagnosis. Midbody dorsal cirri slender, moderately long; antennae, tentacular and anterior dorsal cirri longer than those of midbody. Compound chaetae with short, bidentate blades. Pharynx and proventricle short. Pharyngeal tooth elongate, located slightly back from anterior margin of pharynx. Posterior aciculae ending in rounded, apparently hollow, tips.

Description. Longest complete specimen examined 6 mm long, 0.35 mm wide, with 57 chaetigers. Body slender, pale, without colour markings. Prostomium more or less oval; four eyes in open trapezoidal arrangement. Palps similar in length to prostomium ( Fig. 4A ). Median antenna arising between posterior eyes, with about 20–25 articles, longer than combined length of prostomium and palps; lateral antennae shorter than median one, with about 14–16 articles. Peristomium similar in length to subsequent segments ( Fig. 4A ). Dorsal tentacular cirri shorter than median antenna, with about 16–17 articles; ventral tentacular cirri distinctly shorter than dorsal ones, with about 10– 12 articles. Dorsal parapodial cirri elongated, alternating long, similar in length to body width, and short, with 18–20 and 14–15 articles ( Fig. 4A ); dorsal parapodial cirri of first chaetiger slightly longer than dorsal tentacular cirri, with up to 20 articles. Parapodia distally slightly bilobed. Ventral parapodial cirri digitiform. Compound chaetae bidentate falcigers, with proximal tooth smaller than distal tooth ( Fig. 4B, C, D ) and short to moderate spines on margin, diminishing in length from basal to distal region; shafts of posterior chaetae slightly larger. Anterior parapodia each with 10–12 compound chaetae, blades with dorso-ventral gradation, 30–31 μm long above, 15 μm long below ( Fig. 4B ); midbody and posterior parapodia each with 6–8 compound chaetae, with less marked dorsoventral gradation in length than those of anterior parapodia, blades about 25 μm long above, 20 μm long below ( Fig. 4C, D ). Dorsal simple chaetae on posterior parapodia only, smooth, distally bifid ( Fig. 4H ). Ventral simple chaetae on far posterior segments only, and only on some specimens, slender, bidentate ( Fig. 4I ). Aciculae distally rounded, apparently with hollow tips ( Fig. 4E, F, G ), three on each anterior parapodium, two in midbody parapodia and solitary on posterior ones. Pharynx extending through about 3–4 segments; pharyngeal tooth, dagger-shaped, located posteriorly to anterior margin ( Fig. 4A ). Proventricle through about 3–5 segments, with about 27–30 muscle cell rows. Pygidium with two anal cirri, with about 15 articles, and median stylus. Several specimens are developing sexual stolons, and others show posterior regeneration after detaching stolons.

Remarks. This species is quite similar to Syllis prolifera Kohn, 1852 from European coasts, with a similar body, aciculae and chaetae. Also, both species have a relatively short pharynx and proventricle, with the pharyngeal tooth located distally from the anterior margin (see San Martín 2003). However, S. busseltonensis has a longer, daggershaped pharyngeal tooth, and the chaetae, although similar, are slightly different being more markedly bidentate.

Hartmann-Schröder (1980) reported Syllis prolifera (as Typosyllis (Typosyllis) cf. prolifera ) with doubtful records from Exmouth, and Hutchings & Murray (1984) reported Typosyllis prolifera from Hawkesbury River; however, their description does not match with that species but with S. imajimai n. sp. (see below). So, we conclude that probably S. prolifera does not occur in Australia.

Distribution. Australia (NSW, VIC, SA, WA). Polynesia.

Habitat. Among algae, with or without sediments.

Figures

FIGURE 4. Syllis busseltonensis (Hartmann-Schröder, 1982), n. comb.AM W.53906.A, anterior end, dorsal view. B, falcigers, anterior parapodium. C, falcigers, midbody parapodium. D, falcigers, posterior parapodium. E, aciculae, anterior parapodium. F, aciculae, midbody parapodium. G, acicula, posterior parapodium. H, dorsal simple chaeta. I, ventral simple chaeta. Scale. A: 0.2 mm. B–I: 20 µm.