Syllis komodoensis, 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 : 27-31

Syllis komodoensis n. sp.

Figs 11–13

Material examined. Holotype ZMA V.Pol. 5263 and 4 paratypes (one mounted for SEM) ZMA V.Pol. 5264, Indonesia, Komodo, NE cape, 08°29'S 119°34.1'E, edge of narrow coastal reef, sloping down to sandy bottom with algae, occasional sponges and tunicates, 30–34 m, Snellius II, Sta. 4.096d, 19/ 20 Sept. 1984.

Comparative material examined. Syllis hyalina Grube, 1863 . 1 syntype MPW 396, Adriatic Sea, Croatia, Lussin (= Losinj).

Syllis armillaris . Several spec. MNCN 16.01/7906-07, Spain, Almería, Cabo de Gata, 2 m, 36º46’49.11’’N 2º14’25.31’’W, Jan. 1987. (Identified by San Martín, 2003).

Description. Holotype 12.2 mm long, 0.4 mm wide, with 93 segments; paratypes 15 mm, 7.5 mm and 6 mm long, 0.4 mm wide, with 109, 72 and 62 segments respectively. Prostomium wider than long, with two pairs of eyes in trapezoidal arrangement, anterior ones larger than posterior pair, eye spots absent ( Fig. 11 A). Median antenna inserted on middle of prostomium ( Figs 11 A, 13A, B), slightly longer than combined length of prostomium and palps, with 16 articles; lateral antennae shorter, inserted on anterior margin of prostomium, with 10–12 articles. Palps triangular, longer than prostomium, fused at base, with distinct median groove. Nuchal organs forming ciliary groove between prostomium and peristomium ( Fig. 13 B). Peristomium similar in length to subsequent segments. Two pairs of tentacular cirri: dorsal ones longer than antennae, with 25 articles, ventral ones shorter, with 11 articles. Dorsal cirri of most anterior segments with 17–22 articles. From segment four towards posterior end dorsal cirri shorter, alternating in length, shortest with nine, longest with 13 articles. Basal articles narrower than distal ones, increasing in width and length in middle of cirri, becoming short and narrow again distally ( Figs 12 A, B). Spiral glands inside articles. Anterior ventral cirri digitiform, inserted proximally and reaching distal end of parapodia ( Fig. 12 A). Ventral cirri becoming shorter from midbody (after the proventricle) to posterior end, being pear- shaped on posterior parapodia ( Fig. 12 B). Anterior parapodia each with nine compound, heterogomph chaetae. Long bidentate blades, dorsoventrally decreasing in length (ca. 40 µm dorsal-most, ca. 20 µm ventral-most), short spines on edge ( Figs 11 C, 13C, E). Midbody parapodia with nine compound chaetae, bidentate blades similar in length to anterior ones, longer spines on edge ( Figs 11 D, 13F). Posterior parapodia with 11 compound chaetae, blades bidentate, shorter than those of anterior parapodia (dorsal-most ca. 30 µm, ventral-most ca. 16 µm), spines on edge ( Figs 11 F, 13G, H). Dorsal simple chaetae on posterior parapodia, distinctly bidentate, with short subdistal spines on edge ( Fig. 11 H). Ventral simple chaetae on posterior parapodia, bidentate with short spines on edge ( Fig. 11 I). Anterior parapodia with three to four pointed aciculae, distally curving ( Figs 11 B, 13D, E); midbody with two pointed aciculae protruding from each parapodial lobe ( Figs 11 E, 12A); posterior segments with a single huge, straight and protruding acicula ( Figs 12 B, C). Pygidium conical with two short anal cirri (three articles, 11 in one paratype) and one medial anal papilla (only visible in one paratype) ( Fig. 11 G). Pharynx similar in length to proventricle, through nine segments; conical tooth on anterior margin. Proventricle extending through eight segments, with about 24 rows of muscular cells ( Fig. 11 A).

Remarks. Syllis komodoensis n. sp., is characterized by short dorsal cirri (shorter than body width), long bidentate blades on midbody to posterior chaetigers and one large acicula distinctly protruding from parapodial lobes on posterior parapodia. Syllis komodoensis n. sp. shares some characters with other species of Syllis but this combination of characters is not present in any other described species. Several species have similar dorsal cirri but differ in other characters. In S. hyalina , S. armillaris (both regarded as a cosmopolitan species) and S. pseudoarmillaris Nogueira & San Martín, 2002 (Atlantic Ocean), blades’ length of midbody to posterior chaetae and their spines are shorter, and the posterior aciculae are much smaller ( Nogueira & San Martín, 2002). Syllis mayeri Musco & Giangrande, 2005 (Caribbean) has unidentate posterior compound chaetae, tending to an “ypsiloid” condition ( Musco & Giangrande, 2005) (the term “ypsiloid” is used to describe a thick Y-shaped chaeta produced by total or partial fusion of shaft and blade). Syllis gracilis Grube, 1840 (regarded as a cosmopolitan species) and S. magellanica Augener, 1918 (Pacific and Indian Ocean) possess ypsiloid chaetae ( Grube, 1840; Augener, 1918; Licher, 1999; San Martín, 2003). Another important character, shared with a different group of taxa, is the presence of one large acicula emerging from the posterior parapodia; but, Syllis aciculata Treadwell, 1945 (Pacific Ocean, China Sea) has long dorsal cirri (longer than body width, about 20–24 articles in midbody chaetigers) and parapodia with pre- and postchaetal lobes ( Treadwell, 1945; Licher, 1999). Syllis variegata Grube, 1860 (regarded as a cosmopolitan species) has shorter blades in its compound chaetae, with short and thick spines and a characteristic colour pattern ( Grube, 1860; Licher, 1999). Finally, Syllis crassicirrata Hartmann-Schröder, 1979 (Pacific and Indian Ocean) has compound chaetae with much shorter blades and very long dorsal cirri (40 articles) ( Hartmann-Schröder, 1979; Licher, 1999). Length and shape of blades are similar to those present in Syllis gerlachi ( Hartmann-Schröder, 1960) (Red Sea, Mediterranean Sea, Caribbean and Indian Ocean). However, this taxon has a truncate posterior acicula and one thick and truncate simple dorsal chaeta ( San Martín, 2003).

Distribution. Indonesia.

Etymology. The specific name refers to the type-locality, the island of Komodo.

Figures

FIGURE 11. Syllis komodoensis n. sp. A: Anterior part, dorsal view; B: Anterior aciculae; C: Anterior chaetae; D: Midbody chaetae; E: Midbody aciculae; F: Posterior chaetae; G: Posterior part, dorsal view; H: Dorsal simple chaeta; I: Ventral simple chaeta. Scale A, G: 0.2 mm; B – C: 20 µm; D: 10 µm; E, H – I: 20 ¦ Ìm; F: 5 µm. All holotype ZMA V. Pol. 5263, except for G, paratype ZMA V. Pol. 5264.

FIGURE 12. Syllis komodoensis n. sp. Holotype ZMA V. Pol. 5263. A: Midbody parapodium, anterior view; B: Posterior parapodium, anterior view; C: Posterior acicula. Scale A, B: 48 µm; C: 20 µm.

FIGURE 13. Syllis komodoensis n. sp. Paratype ZMA V. Pol. 5264. SEM. A: Anterior part, dorsal view; B: Prostomium, dorsal view; C: Anterior chaetae; D: Anterior parapodia, dorsal view; E: Anterior midbody parapodia, dorsal view; F: