Acryptolaria niobae Peña Cantero & Vervoort 2010, n. sp.

Acryptolaria niobae n. sp. (Figs 19; 30; 32C; Table 20)

TYPE MATERIAL. — Loyalty Islands. BIOCAL 1, stn DW 08, 20°34.351’- 20°35.092’S, 166°53.904’- 166°54.051’E, 435 m, 12.VIII.1985, 1 stem c. 23 mm high, holotype (MNHN-Hy.2009-0167).

Norfolk Ridge. CHALCAL 2, stn DW 76, 23°40.50’S- 167°45.20’E, 470 m, 30.X.1986, 1 stem 25 mm high, paratype (MNHN-Hy.2009-0156, slide); 1 stem 35 mm high, paratype (RMNH-Coel. no. 35020, slides 448).

OTHER MATERIAL EXAMINED. — Loyalty Islands. BIOGEOCAL, stn CP 290, 20°36.01’- 20°37.26’S, 167°03.34’- 167°03.60’E, 920- 760 m, 27.IV.1987, 1 basally broken, unbranched stem c. 15 mm high (MNHN-Hy.2009-0155, slide).

Norfolk Ridge. BIOCAL 1, stn DW 66, 24°55.435’- 24°54.849’S, 168°21.678’- 168°21.995’E, 515- 505 m, 3.IX.1985, 1 stem c. 16 mm high in slide (MNCN 2.03/398).

ETYMOLOGY. — The specific name niobae is a dedication to Níobe Peña Sancho, daughter of the first author. It is a noun in female genitive.

ECOLOGY AND DISTRIBUTION. — Acryptolaria niobae n. sp. originates from the Loyalty Islands and the Norfolk Ridge areas where it was collected at depths between 435 and 920 m.

DESCRIPTION

Stems up to 23 mm high, very scarcely branched (Fig. 32C); the largest stem with just a primary branch giving rise to a secondary one. Branches with an inconspicuous zigzag arrangement (Fig. 19A).

Hydrothecae alternately arranged in approximately one plane (Fig. 19A), tubular (Fig. 19), cylindrical in distal fourth, diameter slightly decreasing basally and reaching minimum diameter a little above the point where the hydrotheca becomes adnate. At that point the hydrotheca widens slightly and contributes to the formation of an expanded part of the branch (Fig. 19C); the diameter at adnate part remains roughly uniform (Fig. 19). Free part of hydrotheca basically straight, strongly directed outwards due to sharp inflection at the point where the hydrotheca becomes free. Hydrotheca adnate for approximately one-fifth of its adcauline wall (adnate/free ratio 0.2); that wall straight at adnate part and straight or slightly convex at its free portion; abcauline wall slightly concave, straight at distal part. Hydrothecal aperture circular, oblique and directed upwards, forming an angle of c. 45° with long axis of internode. Rim even, frequently with a few short renovations (Fig. 19A).

Large nematocysts relatively large and bananashaped (Fig. 30).

Coppinia not found.

REMARKS

Acryptolaria niobae n. sp. is a very peculiar species.It resembles A. infinita n. sp. in the long hydrothecae and in the colony structure, having only few ramifications and branches with a slight zigzag disposition. Nevertheless, they are distinguishable by several features.First of all the hydrotheca in A. infinita n. sp. is smoothly curved outwards,lacking the characteristic widening at the point where hydrotheca and branch meet observed in A. niobae n. sp. Moreover, in A. infinita n. sp. the hydrotheca is approximately cylindrical at the free portion and much larger. They also differ in the size of the nematocysts, which are much smaller in A. infinita n. sp. (14.8 × 8.1 Μm), and in the extremely small adnate portion of the hydrotheca in A. niobae n. sp.