Erinaceusyllis carrascoi, Soto & Martín, 2017

Soto, Eulogio H. & Martín, Guillermo San, 2017, Exogoninae (Annelida: Syllidae) from Chilean Patagonia, Zootaxa 4353 (3), pp. 521-539 : 531

Erinaceusyllis carrascoi new species

Figure 6

Material examined. Station 41, holotype ( MNCN 16.01/17769) and paratype. Station 36 (2) ( LBUV).

Description. Holotype complete female carrying eggs dorsally. Body small to minute, 2.2 mm long, 0.18 mm wide, with 24 chaetigers; body covered with small, scattered papillae ( Fig. 6A ). Prostomium oval, wider than long; four large eyes in trapezoidal arrangement, nearly in line, and two anterior eyespots; antennae spindle-shaped, basally bulbous; medial tentacle detached in both specimens; lateral antennae inserted slightly anteriorly to anterior pair of eyes, each bulbous basally, with short tips ( Fig. 6A ). Palps shorter than prostomium, fused along their length, with a median scar. Peristomium shorter than subsequent segments, forming a bilobate fold over posterior part of prostomium; tentacular cirri similar to lateral antennae. Dorsal cirri lacking on chaetiger 2; anterior dorsal cirri similar to lateral antennae, basally inflated, spherical, but with longer tips and some minute, rounded papillae, and some with internal, granular glands ( Fig. 6A ); papillae becoming progressively longer on mid-body, with less bulbous bases and much longer tips, then becoming shorter again on posterior parapodia ( Fig. 6B ). Parapodial lobes conical, with few short papillae and one long distal papilla posterior to acicula and two ventrolateral papillae on anterior surface ( Fig. 6C ). Ventral cirri short, digitiform. Compound chaetae heterogomph, with smooth shafts; blades elongate, slender, unidentate, slightly hooked distally, with short marginal spines ( Figs 6E, G ); anterior parapodia each with seven compound chaetae, each with slight dorso-ventral gradation in length, 25 mm above, 20 mm below; number of compound chaetae and length of blades decreasing posteriorly; posterior parapodia each with four compound chaetae, similar to those of anterior parapodia, blades similar but shorter, about 20 mm above 15 mm below. Dorsal simple chaetae from chaetiger 1, each distally entire, smooth, slender, and curved ( Fig. 6D, F ). Ventral simple chaetae on posterior parapodia, similar to dorsal simple chaetae but shorter and slender ( Fig. 6H ). Acicula solitary, acuminate ( Figs. 6C ). Pharynx proportionally slender, through four segments; pharyngeal tooth small, oval, located near opening ( Fig. 6A ). Proventricle barrel-shaped, through three segments, with about 15 muscle cell rows. Pygidium small, with two long anal cirri, similar to dorsal cirri of midbody.

Remarks. Erinaceusyllis carrascoi n. sp. is characterized by having compound chaetae with slender, unidentate blades with short, straight spines on margin, lack of dorsal cirri on chaetiger 2, and presence of papillae on parapodia and dorsal cirri.

About 12 species of Erinaceusyllis have unidentate compound chaetae, but none has long papillae on the parapodial lobes and papillae on the dorsal cirri, except E. cirripapillata San Martín, 2005 from Australia. However, that species has longer, mushroom-shaped papillae on the dorsal cirri ( San Martín, 2005); these are short and rounded in E. carrascoi n. sp.

Erinaceusyllis horrockensis (Hartmann-Schröder, 1981) , also from Australia, has similar compound chaetae, but has dorsal cirri on chaetiger 2 ( San Martín, 2005). Erinaceusyllis centroamericana (Hartmann-Schröder, 1959) a circuntropical species, E. serratosetosa (Hartmann-Schröder, 1982) from Australia, also reported to the Western Mediterranean, and E. ettienei San Martín, 2005 from Australia, have compound chaetae with longer blades and longer spines on the margin ( San Martín, 2005). Erinaceusyllis opisthodentata (Hartmann-Schröder, 1987) , E. kathrynae San Martín, 2005 , and E. hartmannschroederae San Martín, 2005 , all from Australia have, in contrast with the previous species, compound chaetae with short blades, E. opisthodentata also with the pharyngeal tooth located more posteriorly than in E. carrascoi n. sp. ( San Martín, 2005).

Erinaceusyllis nana Ding & Westheide, 2008 , an even smaller species from China, has very similar compound chaetae, but lacks long papillae on the parapodial lobes and has smoth dorsal cirri ( Ding & Westheide, 2008).

Erinaceusyllis bidentata ( Hartmann-Schröder, 1974) from East Africa, Australia and Chile, also has papillae on the dorsal cirri, but the compound chaetae are bidentate ( San Martín, 2005).

Finally, E. erinaceus ( Claparède, 1863), from N Atlantic and N Pacific, has longer compound chaetae with longer marginal spines, and lacks papillae on the dorsal cirri and long papillae on the parapodia ( Verdes et al., 2013).

Distribution. Chilean Patagonia: from Concepción channel to Magellan Strait (50°16 ʹS - 54°57 ʹ S).

Habitat. Shallow subtidal (30 m). Inside tubes of Chaetopterus cf. variopedatus in fjords and channels from Patagonia. Salinity: from 30.2 to 35 PSU, temperature: from 8.7 to 8.9°C.

Type locality. Concepción channel, Drumond Hay Island (Chilean Patagonia).

Etymology. This species is named to honor the late Dr. Franklin Carrasco, Chilean polychaetologist.

Figures

FIGURE 6. Erinaceusyllis carrascoi n. sp. MNCN 16.01/17769. Holotype. A, anterior end, dorsal view. B, posterior end, dorsal view. C, parapodial lobe, midbody, antero-lateral view. D, dorsal simple chaeta, anterior parapodium. E, compound chaetae, anterior parapodium. F, dorsal simple chaeta, posterior parapodium. G, compound chaetae, posterior parapodium. H, ventral simple chaeta. Scale bars. A: 0.1 mm.B–H:20 µm.