Neogyptis nonatoi, 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 : 278-280

Neogyptis nonatoi n. sp.

( Fig. 4 )

Type material. Holotype, MZUSP 386, 23°46.955' S 45°10.421' W, off São Sebastião, SP, Sta. 156I, subtidal, 39.3 m depth, fine sand, 27.VI.2002; paratype (1): MZUSP 385 (1), 23°33.745' S 45°04.038' W, off Ubatuba, SP, Sta. 131I, subtidal, 23.4 m depth, very fine sand, 23.III.2002.

Description. Incomplete individuals; holotype 3.5 mm long, 2.0 mm wide, and paratype 2.5 mm long, 1.1 mm wide; both with 10 chaetigers. Body whitish; prostomium, basis of parapodial lobes, palpostyles and cirrostyles yellowish to brownish. Reddish pigmentation present on dorsal basal side of tentacular cirri and on posterior side of first parapodial lobes. Body wider anteriorly, posteriorly tapered.

Prostomium rectangular with rounded margin, slightly wider than long ( Figs. 4 A–B); anterior prostomium margin with lateral antennae with two minute lateroventral papillae. Palps placed external to antennae; palpophores long, about two-thirds of palp length; palpostyles digitiform, blunt ( Fig. 4 A). Lateral antennae inserted frontally, digitiform, slender, about as long as palps ( Fig. 4 B); lost in paratype. Median antenna filiform located centrally on prostomium, at the same level as anterior eyes, reaching anterior prostomial margin ( Fig. 4 A); lost in holotype. Two pairs of reddish eyes, dorsolateral; anterior pair larger, semicircular, posterior ones punctiform, closer to each other, located near posterior prostomial margin. Nuchal organ ciliated, dorsolateral, on prostomial posterior margins.

Pharynx muscular, as long as first 8 chaetigers. Pharynx everted in paratype, with 60 fringed papillae and other 7–8 longer papillae, each three times longer than surrounding ones, placed subdistally ( Fig. 4 A). Eight pairs of tentacular cirri, biarticulate; cirrophores short, stout, one-fourth as long as cirrostyles; cirrostyle long, digitiform, moniliform, blunt; dorsal ones longer and stouter than ventral ones. First and second pairs of tentacular cirri dorsolateral; third and fourth lateroventral.

Chaetae from segment 5. First chaetiger uniramous, only with neurochaetae; following chaetigers biramous. Notopodial lobe conical to subtriangular, shorter than neuropodial lobe ( Fig. 4 C). Most dorsal cirri lost, or distally fragmented; cirrophore short, stout, cirrostyle long, smooth. Notoaciculae straight or slightly curved distally, not protruding ( Fig. 4 C). Four types of notochaetae: i) One acicular chaeta, stout, distally blunt, central to the bundle ( Fig. 4 D); ii) about 10 longer capillary chaetae, denticulate ( Fig. 4 E); iii) 1–2 medium-sized capillary chaetae, with two basal rows of alternating denticles ( Fig. 4 F); and iv) a stout short chaeta, serrated, curved, less than half as long as capillary ones, in inferior position ( Fig. 4 G). One neuroacicula, slender, straight or slightly bent, not protruding.

Prechaetal lobe long, distally slender; postchaetal lobe rounded, shorter than prechaetal one ( Fig. 4 C). Ventral cirri digitiform, distally slender, inserted subdistally on parapodial lobe, extending slightly beyond prechaetal lobe; cirrophore indistinct ( Fig. 4 C). Neurochaetae of five types: i) two simple straight chaetae, blunt, striated, margin serrate medially to distally, positioned superiorly in bundle ( Fig. 4 H); ii) about five long heterogomph falcigers, at least twice as long as simple ones, blade long, bidentate, margin slightly serrate, positioned medially to superiorly in bundle ( Fig. 4 I); iii) about seven striated heterogomph falcigers with medium-sized blades, bidentate, smooth; iv) about two falcigers with short falciform blade, smooth, bidentate, positioned medially to inferior on the bundle ( Fig. 4 J); and v) geniculate acicular chaetae, subdistally constricted, tip acute, in inferior position ( Fig. 4 K).

Remarks. In the key, the new species is near of N. mediterranea (Pleijel, 1993) by having pharynx with 20 or more papillae. However, N. nonatoi n. sp. differ by having median antenna blunt, pharynx with 60 papillae, and eyes minute instead of median antenna tapered, pharynx with less than 32 papillae, and eyes large. Neogyptis nonatoi n. sp. also resembles N. crypta (Pleijel, 1993) , and N. plurisetis ( Hilbig, 1992) . Neogyptis nonatoi n. sp. differs from the former by having a few acicular notochaetae with blunt tip, a small number of compound neurochaetae, simple capillary neurochaetae distally curved, and much more slender notopodial and neuropodial lobes. It is distinguishable from N. plurisetis by having five types of neurochaetae. After the study of one paratype of N. plurisetis (USNM 75212), we notice that there is more than one type of neurochaetae, instead of having only falciger chaetae as was indicated in the original description. Besides having compound falcigers, N. plurisetis has only thin simple capillaries, differing from any kind of neurochaetae of N. nonatoi n. sp. Another difference is that the notochaetae of N. plurisetis include 1–2 thin smooth capillaries of about the same length as acicular ones. There are less pharyngeal papillae and these are further apart from each other, and more conical and shorter than those of N. nonatoi , which are fringed, longer, more close-set, and additionally have some even longer lateral papillae. Other species can be separated as indicated in the key below.

Etymology. This species is dedicated to Prof. Edmundo F. Nonato, who was the first Brazilian polychaetologist, as a modest recognition to his enthusiasm for research that started over 60 years ago! Distribution. Brazil, Ubatuba and São Sebastião, SP, in sediments at 23.4–39.3 m depth.

Figures

FIGURE 4. Neogyptis nonatoi new species. A. Paratype MZUSP 385, anterior region in dorsal view, pharynx everted, lateral antennae and tentacular cirri lost; B. Holotype MZUSP 386, anterior region, median antenna lost; C. Same, parapodium 6; D. Same, acicular notochaeta, striated, distally blunt; E. Capillary notochaeta, long, striated, marginally serrated; F. Median capillary notochaeta, with spirally arranged denticles; G. Notochaeta short, curved distally and with serrated coarsely face; H. Simple neurochaeta, distally blunt, marginally serrulated from basal to median portion; I. Heterogomph falciger with long blade, marginally serrulated and distally bidentate; J. Heterogomph falciger with short to median blade, marginally smooth and distally bidentate; K. Geniculate neurochaetae, distally pointed.