dcsimg

Description

provided by NMNH Antarctic Invertebrates

Ophiosteira bullivanti n.sp. (Fig. 1)

Disc high, hemispherical, covered mainly by the six primary plates, of which the radial plates almost cover and obscure the radial shields; each radial plate broadly contiguous with ihe large, pentagonal centrodorsal, and separated from the adjoining radials by only one small interradial platelet on either side; the primaries are extremely high and tumid, and collectively resemble a small starfish resting on the disc; oral shield small, pentagonal, with an acute angle proximad; ca. 4 flat, rounded oral papillae, confluent with the tentacle-scales of the oral tentacle-pore; 2 scales on either side of oral tentacle-pore; succeeding pore with 3-4 scales on the proximal margin, and 2-3 on the distal margin; distally the number of scales progressively less, till none remain; tipper arm-plates broadly contiguous, each with a high median crest (which becomes more like a tubercle on distal plates); lateral plates broadly contiguous below, each bearing three small conical arm-spines on the lower distal margin; lower arm-plates lozenge-shaped, small, widely separated; genital clefts conspicuous, extend­ing to the margin, with papillae on the interradial border.

TYPE LOCALITY. N.Z. Oceanographic Institute Station A526, 7/2/1960. 74° 07' S., 177° 41' W., 461-465 in, Pennell Bank, Ross Sea. J. S. Bullivant.

HOLOTYPE. In the collection of the N.Z. Oceanographic Institute, Wellington. R. 11 mm, r 2 mm. Colour in spirit, dull grey.

REMARKS. This species, when first taken, was assumed to be the juvenile stage of Ophiosteira rotundata Koehler. However, it was subsequently found at other stations, on each occasion represented by a form of the same size and appearance as the one selected as holotype, with the genital clefts fully developed, and in no case was it associated with specimens of O. rotundata. It is therefore to be con­sidered as a distinct species, differing from all known species of Ophiosteira in the relatively small body-size, and the relatively massive, broad, tumid primary plates.”

(Fell, 1961; 841)