Tokoprymno anatis Zapata-Guardiola & López-González, 2010, sp. nov.

Tokoprymno anatis sp. nov.

Figures 13–16

Material examined. Holotype: ZMH C11749, ANT XIX/3, stn PS61/046-08, 60°38.79'S, 53°57.42'W, north east of Elephant Island, Antarctica, 2895.6–2896.4 m depth, 2 February 2002, one colony, fragmented. Fragments of the holotype have also been deposited in USNM 1145316.

Description of the holotype. Colony bottlebrush (Figure 13 A), fragmented in three main parts of 5, 7 and 9.5 cm in length, 22 cm in total length and 10.5 cm in width. Simple or scarcely ramified stiff branchlets (Figure 13 B) up to 6.5 cm in length, proximally almost perpendicular to stem, then curving upward. Axis bronze, stiff, broken proximally. Basal axis diameter 3 mm.

Polyps perpendicular to branchlets (Figure 13 B, 14A), absent on main stem, singly or biserial placed (Figure 14 A), 6–11 polyps per cm. Polyps (Figure 14) relatively elongate, slightly clavate, up to 2.4 mm in height and 0.61–0.97 mm in diameter, with a conical operculum. Polyp body with 8 longitudinal rows of scales somewhat disorganized, adaxial body scales smaller (Figure 14 B), 4–5 transverse rows of scales in the abaxial aspect overlapping one another (Figure 14 C).

Accessory opercular scales (Figure 15 A), blade-shaped, variable in number from absent to two, small, about 0.49 mm in height and 0.12 mm in width. Proximal half of inner surface tuberculate, smooth distally, without keel. Margin finely serrated. Outer surface almost smooth, few granules.

Opercular scales (Figure 15 B) eight in number, 0.58–0.84 mm in height and 0.15–0.28 mm in width, duck-beak shaped with rounded tips and square or bilobed base. Proximal inner surface tuberculate covering up to half of their length; distal part convex, with granules forming ridges or with a small keel. Outer surface almost smooth with a few granules proximally. Free margin serrated.

Marginal scales (Figure 15 C) eight in number, more-or-less triangular, 0.52–0.91 mm in height and 0.27– 0.44 mm in width. Inner surface tuberculate covering at least 75% of the scale, with distal longitudinal ridges. Outer surface almost smooth, with a few granules on proximal portion. Free margin serrated, proximal margin granular and lobed.

Body wall scales (Figure 16 A) roughly square shaped, 0.36–0.61 mm in maximum length. Inner surface almost completely tuberculate, outer surface almost smooth and covered with granules proximally. Free margin serrated with tendency to be lobed, basal margin as in marginal scales.

Coenenchyme scales (Figure 16 B) round in shape, 0.18–0.34 mm in maximum length. Inner surface completely tuberculate, outer surface smooth with a few granules. Margin quite smooth, granulate or finely serrated.

Geographic and bathymetric distribution. At present, Tokoprymno anatis sp. nov. is only known from off Elephant Island, Antarctica (Figure 1), between 2895.6 and 2896.4 m in depth.

Etymology. The species name anatis, derived from the Latin and meaning duck-like, refers to the distinct shape of the opercular scales for their similarity to the beak of a duck.

Remarks. According to Cairn’s and Bayer's (2009) generic review of the gorgonian family Primnoidae, the new taxon is included in the genus Tokoprymno Bayer, 1996 due to: (1) the presence of marginal scales of polyps not forming a circumoperculum (Figure 14), (2) the presence of an abundantly branched colony giving a bottlebrush shape (Figure 13 A), (3) the fact that the polyps are often arranged biserially (Figure 13 B, 14A), and (4) the opercular scales having a small keel on their inner surface. However, some species in the genus Thouarella also have a bottlebrush colony shape, polyps arranged singly, and the presence of a keel on the opercular scales. In Thouarella, however, the marginals fold over the bases of the operculars forming a circumoperculum. In fact, this character is used to segregate both genera in Cairn’s and Bayer’s key.

Also according to Cairns and Bayer (2009), the genera Plumarella Gray, 1870 and Acanthoprimnoa Cairns and Bayer, 2004 are morphologically closely related to the genus Tokoprymno. They can be distinguished, however, by the absence of a keel on the opercular scales, as well as their uniplanar colony shape (Gray, 1870; Cairns & Bayer, 2004), while Tokoprymno has a keel on the operculars (Figure 14 B) and a bottlebrush colony shape (Figure 13 A).

The genus Tokoprymno has currently only one described species, Tokoprymno maia Bayer, 1996. This species is clearly differentiated from T. anatis sp. nov. by the size of the polyps, from 3 to 5 mm in the former (Bayer, 1996: 514) depending on the kind of polyp (vegetative or brooder) and up to 2.4 mm in the latter; and by the distinct duck-beak shape of the opercular scales in T. anatis sp. nov. (Figure 15 A), while in T. maia the operculars are isosceles triangle shaped (see Figure 4 in Bayer, 1996) and for the absence of accesory opercular scales in T. maia.