Syllis villenai, Aguado, Teresa, Martín, Guillermo San & Ten, Harry A., 2008

Aguado, Teresa, Martín, Guillermo San & Ten, Harry A., 2008, Syllidae (Annelida: Polychaeta) from Indonesia collected by the Siboga (1899 – 1900) and Snellius II (1984) expeditions, Zootaxa 1673, pp. 1-48 : 34-36

Syllis villenai n. sp.

Fig. 15

Material examined. Holotype ZMA V.Pol. 1985.01 (as Syllis exilis ), Indonesia, 5°56.7’N 126°25’E, 0–36 m, Siboga Expedition, Sta. 133, 25/ 27 July 1899.

Description. Specimen 40 mm long, 1 mm wide, with 192 segments. Body strongly pigmented red. Prostomium wider than long, with two pairs of eyes in trapezoidal arrangement. Median antenna arising from middle of prostomium, long, with 42 articles, reaching to segment 10; lateral antennae inserted at anterior margin of prostomium, shorter than median one, slightly longer than combined length of prostomium and palps, with 22–28 articles. Palps broad, slightly longer than prostomium, fused at base, with a distinct median groove ( Fig. 15 A). Peristomium similar in length to subsequent segments, with two pairs of tentacular cirri. Dorsal tentacular cirri with 43 articles, ventral ones shorter with 22–24 articles. Anterior and midbody parapodia longer than posterior ones. Pre- and postchaetal lobes present on all parapodia, both similar in length ( Fig. 15 G). Dorsal cirri long ( Fig. 15 A) inserted far above parapodia, with spiral inclusions within all articles ( Fig. 15 G). Dorsal cirri alternating in length in anterior and middle part of body ( Fig. 15 A), longer ones with 50– 80, shorter with 30–40 articles. In posterior part longer cirri with 40–50 articles, shorter with 15. Distinct cirrophores present on all segments. Ventral cirri digitiform, not extending beyond parapodial lobes, inserted on middle of parapodia on anterior and midbody parapodia ( Fig. 15 G), becoming more proximally inserted posteriorly. Distinct dark parapodial glands present from segment 22 onwards ( Fig. 15 G). Anterior parapodia each with 12 compound, heterogomph chaetae; distal part of shafts provided with spines, bidentate blades (ca. 40 µm dorsal-most, 35 µm ventral-most), both teeth similar in size and length; edge with long spines, longer than distal tooth ( Fig. 15 B). Midbody and posterior chaetigers with 8–12 compound heterogomph chaetae, dorsoventrally decreasing in length (ca. 35 µm dorsal-most, ca. 30 µm ventral-most), proximal tooth slightly bigger than distal one, both robust. Most ventral blades on posterior parapodia with four to five long and thin spines on margin, not exceeding distal tooth in length ( Fig. 15 C). Dorsal and ventral simple chaetae not seen. Three straight aciculae per parapodium ( Figs 15 D, E). Pygidium conical, with two long articulated anal cirri, with 27–28 articles ( Fig. 15 F). Pharynx long, extending through 14 segments, with pharyngeal tooth on anterior margin, crowned by ten triangular papillae. Proventricle long, extending through 15 segments, cell-rows difficult to distinguish ( Fig. 15 A).

Remarks. Syllis villenai n. sp., is characterized by having long dorsal cirri which alternate in length (30– 80 articles in midbody chaetigers), bidentate compound chaetae with long spines on edge of blade, with thick and rounded distal teeth on posterior parapodia; long pharynx and proventricle and dark parapodial glands in midbody to posterior chaetigers. The similar Syllis lutea (originally described from the Red Sea) also has bidentate compound chaetae with long spinulation and distal thicker teeth in the posterior part of the body. However, in anterior and midbody parapodia of S. lutea long spines are only present on the most ventral chaetae, the most dorsal ones have shorter spines. In posterior parapodia, basal spines remain short and only in the distal edge of the blade, do spines become as long as the distal teeth ( Hartmann-Schröder, 1960, Licher, 1999). Syllis glarearia Westheide, 1974 (Pacific Ocean) is also similar in having long spines and thick distal teeth, but the anterior blades are considerably shorter and there are only two or three long spines on the distal part of the edge ( Westheide, 1974, Licher, 1999). Syllis bifurcata Hartmann-Schröder, 1980 (Indian Ocean and Caribbean) also has posterior bidentate compound chaetae with enlarged distal teeth, but it differs in the length of dorsal cirri (22–27 articles in midbody chaetigers), with blades with shorter spines and fangs with two distal tips, one of them extremely large on posterior chaetae ( Hartmann-Schröder, 1980; Licher, 1999). Although there is only one specimen, we believe that is so distinctive to be described as a new species.

Distribution. Indonesia.

Etymology. This species is dedicated to Miguel Villena, the curator Invertebrates of the MNCN, who has assisted and help us in several studies with loan and deposition of material.

Figures

FIGURE 15. Syllis villenai n. sp. Holotype ZMA V. Pol. 1985.01. A: Anterior part, dorsal view; B: Anterior chaetae; C: Posterior chaetae; D: Anterior aciculae; E: Posterior aciculae; F: Posterior part, dorsal view; G: Midbody parapodium, anterior view. Scale A, F: 0.5 mm; B – E: 20 µm; G: 48 µm.