Syllis deleoni, Salcedo, Diana L. & Solís-Weiss, Guillermo San Martín And Vivianne, 2012

Salcedo, Diana L. & Solís-Weiss, Guillermo San Martín And Vivianne, 2012, The genus Syllis (Polychaeta: Syllidae: Syllinae) in the southern Mexican Pacific, with the description of two new species and three new records, Zootaxa 3263, pp. 47-62 : 56-60

Syllis deleoni n. sp.

( Figs 4 A–C, 5A–F, 6A–F, 7A–D)

Material examined. 13 specimens. Holotype complete specimen (CPICML POH-37-004), El Jardín E3B1, 16°49.436’N, 99°54.981’W, 26 May 2006, 12 m, coarse sand. Paratypes: 3 specimens (CPICML POP-37-005), El Jardín E3B1, 16°49.436’N, 99°54.981’W, 26 May 2006, 12 m, coarse sand. 3 specimens ( MNCN 16.01/13253), El Jardín E3B1, 16°49.436’N, 99°54.981’W, 26 May 2006, 12 m, coarse sand. 3 specimens ( NHMLA LACM-AHF Poly 3033), El Jardín E3B2, 16°49.436’N, 99°54.981’W, 26 May 2006, 12 m, coarse sand. 3 specimens (AM W38810), Palmitas, E2B1 16°49.420’N, 99°54.733’W, 25 May 2006, 10.5 m, coarse sand.

Additional material. 4 specimens (CPICML PO-37-081), 1 specimen, Caleta E1B2, 16°49.797’N, 99°54.062’W, 25 May 2006, 12 m, coarse sand. 1 specimen, Palmitas E2B2, 16°49.420’N, 99°54.733’W, 25 May 2006, 10.5 m, coarse sand. 2 specimens, El Jardín E3B2, 16°49.436’N, 99°54.981’W, 26 May 2006, 12 m, coarse sand.

Comparative material examined. Syllis corallicoloides , 1 specimen ( MNCN 16.01/8740), SPAIN: Faro de Alboran Is., Almería, Mediterranean Sea, 33– 39 m. Syllis corallicoloides , 9 specimens ( MNCN 16.01/6874), CAPE GREEN ISLANDS: San Vicente Is., Salamansa, Atlantic.

Description. Holotype complete, 10.4 mm long, 0.57 mm wide, 82 chaetigers. Longest complete specimen 16.5 mm long, 0.9 mm wide, 108 chaetigers. Body medium to large, broad, cylindrical, without a distinctive colour pattern. Prostomium oval, wider than long, with two pairs of eyes in trapezoidal arrangement and a pair of small eyespots near anterior margin ( Figs 4 A, 5A). Dorsum provided with numerous minute pores visible under SEM ( Fig. 5 C) and abundant glandular material (more concentrated on the sides of each segment) ( Fig. 4 A). A pair of ciliated nuchal grooves extending along postero-lateral margin of prostomium ( Figs 4 A, 5A). Median antenna much longer than combined length of prostomium and palps, arising between posterior pair of eyes, with about 42 articles; lateral antennae shorter than median one, arising in front of anterior pair of eyes, with about 20–23 articles ( Fig. 4 A). Palps broad, triangular to rounded, as long as the prostomium, basally fused ( Figs 4 A, 5A). Antennae, tentacular cirri and dorsal cirri showing differences in article size and with internal yellowish spiral glands that give articles a dark appearance ( Fig. 4 A); minute pores and cilia arising in the junction between dorsal cirri articles ( Fig. 5 E). Peristomium shorter than subsequent segments, with two pairs of tentacular cirri, dorsal pair with about 58 articles and ventral pair with 21–23 articles. Dorsal cirri long, broad, distally tapering, longer than body width, showing irregular variations in length on anterior part (first pair with 57 articles, second pair with 22–24, third with 16–18, fourth with 30, fifth with 34–36, and sixth with 24–26 articles); alternating in length in midbody and posterior part, longer ones with about 37–46 articles and shorter ones with about 17–23 articles. Ventral cirri short, digitiform to conical, not extending beyond parapodial lobes. Parapodial lobes relatively long, digitiform, with a short and rounded prechaetal lobe. Anterior parapodia each with about 10–12 compound chaetae (between 8.3 and 19.25 Μm) ( Fig. 4 B), about 7–9 compound chaetae in midbody (10.3 to 17.24 Μm) and posterior parapodia (8.62 to 14.13 Μm) ( Fig. 6 A, 6C). All chaetae heterogomph falcigers, bidentate, with rounded to blunt teeth, similar in size. A slightly antero-posterior gradation in blade length, becoming thicker in midbody and posterior parapodia and a slight dorso-ventral gradation in spine length. Most superior and middle chaetae with coarse and long spines, ventralmost chaetae with fine, short, marginal spines ( Figs 4 B, 6A, 6C). A single dorsal simple chaeta per posterior parapodium, straight, bidentate, with both teeth small, similar, and short subdistal spines on margin ( Figs 6 E, 7C); ventral simple chaeta distally bifid, with both teeth rounded, similar, subdistally curved and with short subdistal spines on margin ( Figs 6 F, 7D). Three aciculae per anterior parapodium, two acuminate and one slender and distally blunt ( Fig. 4 C); two in midbody ( Fig. 6 B) and posterior parapodia ( Fig. 6 D), all acuminate, sometimes protruding slightly from parapodial lobes. Posterior parapodia with a few additional slender compound chaetae, similar to those of anterior part. Pharynx long and slender, extending through 10 segments, with a conical tooth on anterior margin ( Fig. 4 A) and a crown of 12 soft papillae ( Fig. 5 B). The largest specimen has a crown with 20 papillae. Proventricle long, extending through 8 segments, with about 35 muscular cell-rows ( Fig. 4 A). Pygidium rounded, with a digitiform median stylus and two anal cirri, with about 27–28 articles.

Remarks. Syllis deleoni n.sp., is characterized by having abundant glandular material on dorsum, a pharynx with a crown with at least 12 soft papillae and compound chaetae bidentate with rounded to pointed teeth. Syllis corallicoloides ( Augener, 1924) (West Indies, Gulf of Mexico, Brazil) and Syllis ergeni Çinar, 2005 (Aegean Sea, eastern Mediterranean Sea) are similar species: Syllis corallicoloides has longer and slender palps and much shorter tentacular and dorsal cirri. Additionally, that species has strongly protruding aciculae, whereas in S. deleoni n.sp., they are completely immersed in parapodial lobes or slightly protruding. Syllis corallicoloides has longer anterior falcigers with strongly rounded teeth. The proventricle is longer in Syllis corallicoloides , although in both species the same number of rows of muscular cells are present. Syllis corallicoloides has about 14–16 papillae on the distal end of pharynx, while in Syllis deleoni between 12 and 20 are present. Apparently, at least in this species, the number of papillae might be related to the size of the individual. Additionally S. ergeni has abundant glandular material on dorsum, but its antennae, and tentacular and dorsal cirri are much shorter. Both species have chaetae with bidentate blades with fine spines, but S. ergeni has longer falcigers on anterior parapodia and has the subdistal tooth smaller than distal one, while S. deleoni n.sp., has both teeth similar in size. The pharynx is longer in S. deleoni n.sp., (extending along 10 segments) than in S. ergeni (extending through 7 segments). Syllis tigrinoides ( Augener, 1924) is another species of the genus with more than 10 papillae on the pharynx, but it has about 19–20. Also, S. corallicoloides has protruding aciculae, strongly rounded teeth on falcigers and coarse and longer spinulation.

Habitat. Coarse sand, subtidal.

Distribution. Western coast of Acapulco Bay, southern Mexican Pacific.

Etymology. The species is named in honor of Dr Jesús Ángel de León González, expert Mexican polychaetologist, for his good and numerous contributions to the knowledge of this group.

Figures

FIGURE 4. Syllis deleoni n. sp. (A) Anterior end, dorsal view. (B) Anterior chaetae. (C) Anterior aciculae. Scale 40 µm.

FIGURE 5. SEM of Syllis deleoni n. sp. (A) Anterior end, dorsal view. (B) Everted pharynx. (C) Dorsum, detail of pores. (D) Dorsal cirri. (E) Dorsal cirri articles, detail of pores and cilia. (E) Anterior chaetae. Scale: (A, D) 100 µm. (B) 20 µm. (C, E – F) 5 µm.

FIGURE 6. Syllis deleoni n. sp. (A) Midbody chaetae. (B) Midbody aciculae. (C) Posterior chaetae. (D) Posterior aciculae. (E) Dorsal simple chaeta. (F) Ventral simple chaeta. Scale 40 µm.