Neopolynoe antarctica ( Kinberg, 1858 ) Kinberg, 1858

Barnich, Ruth, Gambi, Maria Cristina & Fiege, Dieter, 2012, Revision of the genus Polyeunoa McIntosh, 1885 (Polychaeta, Polynoidae), Zootaxa 3523, pp. 25-38 : 34-36

Neopolynoe antarctica ( Kinberg, 1858) n. comb.

Fig. 4 A–I

Polynoe antarctica Kinberg, 1858: 23 ; Kinberg (1910): pl. 10 fig. 58; Fauvel (1936): 13; Uschakov (1962): 176; Hartman (1964): 42; Averincev (1972): 124; Orensanz (1976): 11; Hartmann-Schröder (1983): 262; Hartmann-Schröder (1989): 211, figs. 12–23.

Enipo antarctica: Ehlers (1901) : 47, pl. 4 figs. 6–13.

Harmothoe antarctica: Bergström (1916) : 279.

Type material. Holotype SMNH-Type-527 (in two fragments, few posterior segments missing), “Eugenie“ Exp. 1851–53, St. 1879–81, Magellan Strait, 53°S 72°W.

Additional material. 1 spm. (af), SMF 20030, San José Gulf ( Argentina), Isla de los Pájeros, 18 January 1975, shallow subtidal. 1 spm. (out of 3, cf. Hartmann-Schröder 1989, cs), ZMH V- 4696, Magellan Strait, Punta Arenas.

Diagnosis. Prostomium with distinct cephalic peaks. Antennae and cirri not very long. Elytra, large, overlapping, covering dorsum. Tip of neuropodial acicular lobe extended to thick, stout supra-acicular process. Neurochaetae all bidentate. Ventral cirri short, not reaching to tip of neuropodia.

Description (based on additional spm. SMF 20030 without elytra, completed by spm. ZMH V-4696 for elytra and missing prostomial appendages).

Prostomium bilobed, with distinct cephalic peaks ( Fig. 4 A); ceratophore of median antenna in anterior notch, style smooth, tapering, longer than palps; lateral antennae inserted ventrally to median antenna, styles smooth, tapering; anterior pair of eyes situated dorsolaterally slightly in front of widest part of prostomium, posterior pair dorsally near hind margin of prostomium; palps tapering.

First or tentacular segment with a pair of tentaculophores inserted laterally to prostomium, without notochaetae, but with a dorsal and a ventral tentacular cirrus, styles smooth, tapering ( Fig. 4 A). Second or buccal segment with first pair of elytra, biramous parapodia and long tapering ventral or buccal cirri. Following segments with ventral cirri short, not reaching to tip of neuropodium ( Fig. 4 C).

15 pairs of elytra, large, overlapping, covering dorsum, on segments 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 26, 29, and 32; elytra smooth except for some conical microtubercles near anterior margin (disappearing in posterior elytra) and often with pigmented patches (in ethanol) ( Fig. 4 B). Cirrigerous segments with distinct dorsal tubercles; dorsal cirri with cylindrical cirrophore, styles smooth, tapering ( Fig. 4 C).

Parapodia biramous; notopodia and neuropodia with prominent acicular lobe, tip of neuropodial acicular lobe extended to thick, stout supra-acicular process; tips of noto- and neuroacicula penetrating epidermis ( Fig. 4 C). Notochaetae few, stouter than neurochaetae, with distinct rows of spines and blunt tip ( Fig. 4 D,E); neurochaetae more numerous, with distinct rows of spines distally and bidentate tip with distinct secondary tooth ( Fig. 4 F–I).

Dorsal side of segments with transverse pigmentation (in ethanol).

Measurements. Specimen figured here (SMF 20030, Fig. 4 ): L about 20 mm, W 4 mm for 46 segments (af). Holotype (SMNH-Type-527): L 50 mm, W 6 mm for 80 segments (few posterior segments missing).

Remarks. Ehlers (1901) moved Polynoe antarctica to the genus Enipo Malmgren, 1866 and considered Polyeunoa laevis McIntosh, 1885 to be a synonym. Bergström (1916) did not agree, since Enipo has at least some notochaetae tapering to capillary tip. Additionally, he considered both species to be distinct and moved P. antarctica to the genus Harmothoe Kinberg, 1856 . As demonstrated above, we agree with Bergström and many other authors that both species are distinct and belong to different genera (see also Table 1). But we disagree regarding the affiliation with Harmothoe , since species of this genus are distinctly short-bodied with fewer than 50 segments (for more details regarding other characters of this genus, see Barnich et al. 2006, Barnich & Fiege 2009). Other authors like Hartmann-Schröder (1989) considered the species to belong to Polynoe , but in this genus the notopodium is much shorter and thus less prominent and the notochaetae are more slender than the neurochaetae, while in the present species the notopodium is prominent and the notochaetae are stouter than the neurochaetae. However it can not be attributed to Polyeunoa , since its neuropodia clearly show a stout supraacicular process and its number of elytra is strictly 15 pairs. (See also remarks related to the generic diagnosis above and Tables 1 & 2).

As listed in Table 3 the bidentate neurochaetae clearly distinguish Neopolynoe antarctica from both N. paradoxa and N. acanellae , which so far have not been reported for the southern hemisphere. Further differences from N. paradoxa are the smooth elytra, antennae and cirri and from N. acanellae the thick, stout supra-acicular process and the much shorter ventral cirri.

Distribution. In the SW Atlantic (northwards up to 40°S) and the Magellan region, in 0–300 m depth, on various substrates like sand, stones, mud, between rhizomes of algae, also associated with terebellid polychaetes (cf. Hartmann-Schröder 1989).

2010)

Species / character Neopolynoe antarctica Neopolynoe acanellae (Verrill, Neopolynoe paradoxa (Storm,

( Kinberg, 1858) n. comb. 1881) 1888)

Figures

FIGURE 4. Neopolynoe antarctica (Kinberg, 1858) (SMF 20030). (A) anterior end; styles of antennae and cirri missing, except for right ventral tentacular cirrus, left palp broken, right palp missing; (B) left middle elytron from unknown segment; (C) left, cirrigerous parapodium from segment 14, posterior view, chaetae omitted; (D) long notochaeta; (E) tip of same; (F) distal part of middle neurochaeta; (G) tip of same; (H) tip of upper neurochaeta; (I) tip of lower neurochaeta. (Scales: A, B = 1 mm; C = 500 µm; D, F = 100 µm; E, G – I = 50 µm).