Micropodarke pleijeli, Rizzo, Alexandra E. & Salazar-Vallejo, Sergio I., 2014

Rizzo, Alexandra E. & Salazar-Vallejo, Sergio I., 2014, Hesionidae Grube, 1850 (Annelida: Polychaeta) from South-Southeastern Brazil, with descriptions of four new species, Zootaxa 3856 (2), pp. 267-291 : 271-273

Micropodarke pleijeli n. sp.

( Fig. 1 )

Type material. Holotype, MZUSP 387, 23°26.20' S 41°15.82' W, off Rio de Janeiro State, Sta. 6762, subtidal, 146 m depth, 28.II.1998; paratype, MZUSP 388 (1), 23°49.90' S 43°14.40' W, off Rio de Janeiro State, Sta. 6741, subtidal, 138 m depth, 15.II.1998.

Description. Incomplete individuals; holotype (MZUSP387) 1.3 mm long, 0.6 mm wide, and 8 chaetigers; paratype (MZUSP388) 1.5 mm long, 0.5 mm wide, with 11 chaetigers. Coloration whitish, without pigmentation. Body subcylindrical.

Prostomium quadrangular, slightly wider than long; anterior margin slightly rounded ( Fig. 2 A). Palps located outer to the antennae. Palpophores short, stout; palpostyles globular, slightly longer than palpophores; right one lost on figured paratype ( Fig. 1 A). Lateral antennae frontal, digitiform, distally rounded, long as palps. Eyes not seen. Nuchal organs not seen.

Proboscidial diaphragm present. Pharynx muscular occupying the first five chaetigers. Pharynx everted in holotype, short, smooth, fringed, with about 30 papillae, small, conical, with ciliate tips ( Fig. 1 A). First three segments fused, dorsally reduced. Six pairs of tentacular cirri, most lost; cirrophores short, stout; cirrostyles long, moniliform; first pair dorsolateral, second and third pairs lateroventral; first segment with dorsal tentacular cirri larger, complete, reaching chaetiger 3; ventral cirri slightly shorter than dorsal one.

Parapodia subbiramous. Two straight notoaciculae, not protruding ( Fig. 1 B). Notochaetae absent. Most dorsal cirri lost; when present, cirrophore stout, short, cirrostyle long, moniliform, about as long as body width ( Fig. 1 B). One neuroacicula distally enlarged, rounded, not protruding ( Fig. 1 C). Neuropodial pre- and postchaetal lobes entire, liguliform, both of the same length. Ventral cirri digitiform, distally slender, not annulated, inserted subdistally on parapodial lobe, smaller than dorsal cirri ( Fig. 1 B). Ventral adhesive papillae paired, rounded, situated postero-laterally to parapodia ( Fig. 1 B–D).

Neurochaetae about 15 heterogomph falcigers per bundle; blade medium-sized to long, with a long basal spur (prolonged teeth), one-third as long as blade. Supra-acicular neurochaetae bidentate, with unequal teeth, hooded (hood arises from inferior teeth) ( Fig. 1 E); subacicular ones without hood, unidentate, with teeth stouter, and a basal arista, finer ( Fig. 1 F), and 1–2 longer neurochaetae, slender, unidentate, without hood, in central position ( Fig. 1 G).

Remarks. In the key to species, M. pleijeli n. sp. is nearest of M. trilobata Hartmann-Schröder, 1983 , but differs by having antennae thin, tapered, and palpostyle medially swollen, blunt instead the antennae are thick, blunt, and the palpostyle is medially swollen, tapered. Micropodarke pleijeli n. sp. also differs from M. dubia ( Hessle, 1925) by lacking eyes, having a pharynx with more papillae, and by the neurochaetal features. Pleijel and Rouse (2005) mentioned 20–25 elongated ciliated papillae, while M. pleijeli n. sp. has about 30; also indicated 3–6 neurochaetae in median position having 2–4 basal prolonged teeth or “spurs”; however M. pleijeli n. sp. has only one spur. Besides, the supra-acicular neurochaetae are bidentate, hooded, and the subacicular ones are unidentate, without hood.

Etymology. This species is named after Dr. Fredrik Pleijel for his contributions to the study of the polychaetes in general, especially in recognition of his many, fine publications on hesionid systematics.

Distribution. Brazil, between São Tomé Cape to Ilha Grande Bay, off Rio de Janeiro State, in 138– 146 m. This is the first record of Micropodarke for the Atlantic Ocean.

Figures

FIGURE 1. Micropodarke pleijeli new species. A. Paratype MZUSP 388, anterior region, right dorsolateral view; B. Same, parapodium 11, left side view; C. Same, parapodium 11, right side view; D. Parapodium 6 showing the ventral adhesive papilla (vap), right side view; E. Supra-acicular heterogomph bidentate falciger, with hood and spur; F. Subacicular heterogomph bidentate falciger, without hood; G. Neurochaeta elongated and slender.

FIGURE 2. Syllidia amaralae new species. A. Holotype MZUSP 506 with pharynx everted, dorsal view; B. Same, ventral view; C. Same, jaws; D. Position of jaws and stylet on proboscis; E. Paratype MZUSP 505, parapodium 4, posterior view; F. Same, parapodium 12, anterior view; G. Supra-acicular heterogomph falciger neurochaetae; H. Sub-acicular heterogomph falciger neurochaetae.