Syllis guillei, Núñez & Martín, 2024

Núñez, Jorge & Martín, Guillermo San, 2024, Syllidae Grube, 1850 (Annelida) from Conception, Amanay and Banquete Banks off Canary Islands, with the description of two new species, Zootaxa 5477 (1), pp. 43-65 : 56-57

Syllis guillei , n. sp.

Figures 3–5

Material examined. INFUECO stations: BC9 0710, Holotype ( MNCN 16.01/18957 ) and Paratype ( MNCN 16.01/18958 ), 132 m depth .

Description. Holotype almost complete specimen, stained in red, 10.2 mm long, 0.35 mm wide, with 141 segments. Body long and slender ( Fig. 3A, B ), with numerous short segments, anteriorly ( Fig. 4A ) and posteriorly tapered, with short segments, becoming wider on proventricular segments ( Figs. 3A, B , 4A, B ). Prostomium wider than long, with two pairs of eyes in trapezoidal arrangement. Median antenna arising from middle of prostomium ( Fig. 4B ), broken in all specimens, with 11 articles in holotype; lateral antennae inserted at anterior margin, also broken, except in holotype, with 28 articles. Palps broad, slightly shorter than prostomium, fused at base, with distinct median groove. Peristomium shorter than subsequent segments, with two pairs of tentacular cirri ( Fig. 3B ). Antennae, tentacular and dorsal cirri long, thin, filiform, whip-shapped, with numerous rectangular articles ( Figs. 3A, B , 4A, B ). Dorsal tentacular cirri with 20 articles each, ventral ones shorter, with 15 articles each. Dorsal cirri long, with small, rounded inclusions within all articles. Dorsal cirri with 40-30-25-27-38 articles, respectively, on five most anterior chaetigers; with 37–45 articles on midbody. Distinct cirrophores present on all segments. Ventral cirri digitiform, ovate, not extending beyond parapodial lobes. Anterior parapodia each with 9–10 compound, heterogomph chaetae; distal part of shafts provided with spines; blades short, bidentate, with slight dorso-ventral gradation in length (12 μm dorsally, 9 μm ventrally), both teeth similar in size and length; edge with thin, long spines, short basally and longer distally ( Figs. 4C–E , 5A ). Midbody and posterior segments with 7–8 compound heterogomph chaetae, similar in shape and size to anterior ones, proximal tooth slightly larger than distal one, both robust ( Fig. 5B, C ). Dorsal and ventral simple chaetae not seen. Single acicula per parapodium, slender, distally oblique, similar all along body ( Fig. 5D–F ). Pharynx very long, retracted and folded on all specimens; anterior end of pharynx on chaetiger 11 ( Fig. 3A ), extending to chaetiger 34; middorsal pharyngeal tooth not seen, apparently lacking. Proventricle short, extending through five segments ( Fig. 3B ), with about 20 muscle cell-rows.

Remarks. Syllis guillei n. sp. is characterized by having very long, filiform dorsal cirri, compound chaetae with short bidentate blades, provided with long, thin spines on margin, very long pharynx and short proventricle, and aciculae distally oblique. This species is very similar to Syllis villenai Aguado, San Martín & Ten Hove, 2008 , from Indonesia ( Aguado et al. 2008), in the overall aspect of the body and compound chaetae. However, S. guillei n. sp. differs from S. villenai in several characters. Both species have a long pharynx, but differ in the size of the proventricle, which is long, through 15 segments in S. villenai , and only five in S. guillei , n. sp. The aciculae in S. villenai are distally pointed, three per parapodium, and aciculae are distally oblique, with only one per parapodium, in S. guillei n. sp. Furthermore, S. guillei n. sp. lacks the conspicuous glands in parapodia described for S. villenai . Finally, Syllis villenai was collected in a dredge between 0 and 36 m depth, while S. guillei , n. sp. lives in deeper bottoms.

Etymology. The species is named after Guillermo San Martín Fernández, “Guille”, beloved son of the second author, who passed away in 2023, aged 36.

Habitat. Circalittoral bottoms to 132 m in soft sedimentary substrates.

Distribution. The Banquete Bank, south of Fuerteventura (Canary Islands).

Figures

FIGURE 3. Syllis guillei, n. sp. Holotype. Light microscope photos. A, anterior end, dorsal view. B, anterior segments and proventricle region. Pho=Pharynx opening. Prv= proventricle. Scale. A, B: 1 cm = 0.35 mm

FIGURE 4. Syllis guillei n. sp. SEM micrographs. Paratype. A, anterior end, dorsal view. B, prostomium and most anterior segments, dorsal view. C–E, compound chaetae, anterior segments (bent by effect of electrons flux).

FIGURE 5. Syllis guillei n. sp. Holotype. A, compound chaetae, anterior parapodium. B, compound chaetae, midbody parapodium. C, compound chaetae, posterior parapodium. D, acicula, anterior parapodium. E, acicula, midbody parapodium. F, acicula, posterior parapodium. Scale. 20 µm.