Syllis marceloi, 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 : 222-225

Syllis marceloi n. sp.

Figures 12 , 13

Material examined. AUSTRALIA, NEW SOUTH WALES: Bass Point , 34° 36' S, 150° 54' E, Holotype, AM W.48547, coll. 35–40 m, 3 January 1991, St. T 4-213, Paratype AM W.48548, 1 specimen, coll Jan 1981 by Smith McIntyre grab.

Description. Holotype complete specimen, 28 mm long, 0.52 mm wide, with 177 chaetigers; paratype smaller and incomplete. Body extremely long and slender, markedly cylindrical, without any colour pattern. Prostomium pentagonal; 4 small eyes in open trapezoidal arrangement and 2 minute anterior eyespots. Palps triangular, similar in length to prostomium ( Fig. 12 A). Median antenna arising between posterior eyes, short, slender, with 15 articles; lateral antennae similar to median one, but shorter, with 12–13 articles. Peristomium shorter than subsequent segments, dorsally covering posterior part of prostomium ( Fig. 12 A). Dorsal tentacular cirri longer than median antenna, with about 17 articles; ventral tentacular cirri with 12 articles. Dorsal parapodial cirri slender, short, with few articles ( Fig. 12 B), shorter than body width, with some internal inclusions ( Fig. 12 B); anteriormost dorsal parapodial cirri slightly shorter than dorsal tentacular cirri, with about 19–20 articles alternating with shorter ones, with about 12 articles; from midbody backwards, alternating long (about 15 articles) and short (about 10 articles) dorsal parapodial cirri. Parapodia conical, distally bilobed ( Fig. 12 B, C). Ventral parapodial cirri digitiform, shorter than parapodial lobes ( Fig. 12 B). Compound chaetae with short blades, bidentate with proximal tooth smaller than distal one ( Fig. 13 A, B), except on posterior parapodia, where the proximal tooth is slightly larger ( Fig. 13 A–C); spines on margin of blades short, except distal 1–3, which reach the level of proximal tooth ( Fig. 13 A–C). Anterior parapodia each with about 15 compound chaetae, blades 20 µm long above, 16 µm long below ( Fig. 13 A); midbody parapodia each with 6–7 compound chaetae, blades 26 µm long above, 16 µm long below ( Fig. 13 B); posterior parapodia each with 6 compound chaetae, blades 25 µm long above, 20 µm long below ( Fig. 13 C). Dorsal simple chaetae on posterior parapodia only, relatively thick, unidentate, smooth ( Fig. 12 D). Ventral simple chaetae on far posterior segments only, thick, bidentate, with proximal tooth larger than distal one, with smooth margin ( Fig. 12 E). Anterior aciculae very thick, distally rounded, emerging from parapodial lobes, numbering about 5 per parapodium ( Fig. 13 D); number and shape of aciculae progressively decreasing towards posterior end; in midbody parapodia, 2 straight pointed aciculae, one being slender, and the other distinctly large, protruding from parapodial lobes ( Fig. 13 E), becoming distally oblique in posterior parapodia ( Fig. 12 B, C); one single acicula in posteriormost parapodia, being distinctly large, with oblique tip, and protruding from parapodial lobes ( Fig. 13 F). Pharynx distinctly long, slender, through more than 20 segments (17 in paratype; everted in holotype) ( Fig. 12 A); pharyngeal tooth on anterior margin of pharynx. Proventricle through 16 segments (13 in paratype), with about 48– 50 muscle cell rows. Pygidium with 2 anal cirri, with 20 articles each, and a median stylus.

Remarks. Only two species of the genus Syllis have the combination of characters which characterizes Syllis marceloi n. sp., with a long and slender body, short dorsal cirri, and long pharynx and proventricle: Syllis licheri Ravara, San Martín & Moreira, 2004 , and Syllis pontxioi San Martín & López, 2000 . These two species also have compound chaetae with short, triangular blades. However, in S. licheri the blades are unidentate or almost, with the margin smoth or with short spines while the blades in S. pontxioi , in spite of being quite similar to those of S. marceloi n. sp., have the proximal tooth in the posterior chaetae not as strong as in the latter species, and the spines on the margin are shorter. Furthermore, the pharynx and proventricle of S. licheri and S. pontxioi are not so long as in S. marceloi (see Ravara et al. (2004), San Martín & López (2000) and San Martín (2003) for comparison).

Etymology. The species is named after Dr. Marcelo Veronesi Fukuda, a Brazilian colleague and friend, for his contributions to the knowledge of polychaetes, and Syllidae in particular.

Habitat. Soft sediments in 35– 40 m.

Distribution. Australia (New South Wales).

Figures

FIGURE 12. Syllis marceloi, n. sp. (AM W. 48547 Holotype). A, anterior end, dorsal view. B, mid-posterior parapodium, lateral view. C, detail of distal part of parapodial lobe, dorsal view. D, dorsal simple chaeta. E, ventral simple chaeta. Scale bars: A: 0.4 mm. B, C: 0.1 mm. D, E: 20 µm.

FIGURE 13. Syllis marceloi, n. sp. (AM W. 48547 Holotype). A, compound chaetae, anterior parapodium. B, compound chaetae, midbody parapodium. C, compound chaetae, posterior parapodium. D, aciculae, anterior parapodium. E, aciculae, midbody parapodium. F, acicula, posterior parapodium. vScale bar: 20 µm.