Syllis patersoni Soto, San Martín & Lucas, 2020

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 : 11

Syllis patersoni Soto, San Martín & Lucas, 2020

Figure 6

Syllis patersoni Soto, San Martín & Lucas, 2020: 153 , fig. 7

Material examined. AUSTRALIA, WESTERN AUSTRALIA: Kimberley region, East Montalivet Island , 15° 06’ S, 125° 18’ E, 0–6 m, 15–16 July 1988, intertidal, AM W.54232, 1 specimen . NORTH TERRITORY: Darwin Harbour, NT 349, East Point , 12° 24’ 36” S, 130° 39’ 57” E, coll. by hand on SCUBA, 7–10 m, 17 July 1993, coral rubble and algae, AM W.54231, 1 specimen ; Dudley Point, NT 319, 12° 24’ 54” S, 130° 49’ E, coll. by SCUBA, 7–8 m 18 July 1993, coral rubble and algae, AM W.54230, 1 specimen .

Description. Body elongated, slender, without colour markings; complete, twisted specimen, 8 mm long, 0.35 mm wide, 88 chaetigers. Prostomium almost circular; palps elongated. Dorsal cirri similar in length to body width, longer on anterior segments, slender, elongated, somewhat fusiform, with numerous spiralized glands inside articles ( Fig. 6 , A, B), giving a dark appearance; dorsal cirri from proventricular segments alternating long cirri, with 23 articles, and short ones, with 17 articles ( Fig. 6B ). Parapodia conical; ventral cirri digitiform. Compound chaetae with few short, slender, spiniger-like chaetae ( Fig. 6D, F, H ) and several heterogomph falcigers with bidentate blades, proximal teeth slightly smaller than distal ones, and short spines on margin, with dorso-ventral gradation in length ( Fig. 6C, E, G ), similar throughout. Anterior parapodia each with 2₋₋3 short spiniger-like chaetae, blades 60 µm ( Fig. 6C ) and 11₋₋12 falcigers with dorso-ventral gradation, blades 36 µm above, 23 µm below ( Fig. 6D ); midbody parapodia each with 1₋₋2 spiniger-like chaetae, blades 55 µm long ( Fig. 6E ) and 6₋₋7 falcigers, blades 25 µm above, 16 µm below ( Fig. 6F ); posterior parapodia each with one (sometimes two) spiniger-like chaetae, shorter than those of midbody and anterior segments, blades 52 µm long ( Fig. 6G ), and 5₋₋6 falcigers, blades 20 µm above, 16 µm below ( Fig. 6H ). Dorsal and ventral simple chaetae not seen. Anterior parapodia with four slender, pointed aciculae ( Fig. 6I ), two in midbody parapodia, distinctly thicker ( Fig. 6J ), and one single in posterior parapodia, acuminate ( Fig. 6K ). Pharynx long and slender, through 10 segments. Proventricle slender and long, shorter than pharynx, through seven or eight segments, with 35₋₋47 muscle cell rows. Pygidium small, with two long anal cirri, with 12 articles.

Remarks. The presence of this species in Australia is surprising, since it was described from very cold waters in Chile. However, this specimen agrees quite well with the original description, although the specimen is smaller than the type material. It is very similar to Syllis beneliahuae Campoy & Alquézar, 1982 ) (see Soto et al., 2020), but the dorsal cirri are longer, distally pointed, with more articles, and the spiniger-like chaetae are shorter relative to the falcigers (about twice as long in S. patersoni and three times longer in S. beneliahuae ). However, this distribution should be confirmed by molecular studies.

Distribution. Chilean Patagonia. Australia (WA, NT).

Habitat. From boulders, sediment bottoms and associated with Macrocystis pyrifera holdfasts in fjords, islands and channels from Chilean Patagonia. Shallow subtidal to about 30 m.

Figures

FIGURE 6. Syllis patersoni Soto, San Martín & Lucas, 2020. A, anterior end, dorsal view. B, long and short dorsal cirri, midbody. C, spiniger-like compound chaeta, anterior parapodium. D, falcigers, anterior parapodium. E, spiniger-like compound chaeta, midbody parapodium. F, compound falcigers, midbody parapodium. G, spiniger-like compound chaeta, posterior parapodium. H, falcigers, posterior parapodium. I, aciculae, anterior parapodium. J, aciculae, midbody parapodium. K, acicula, posterior parapodium. AM W.54232. Scale. A: 0.1 mm. B:0.1 mm. C-K: 20 µm.