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Deep-Sea Echinoderms of New Zealand

Family Korethrasteridae

Family Korethrasteridae

This family, usually regarded as transitional between the Pterasteridae and the Solasteridae, has not hitherto been recorded from Australasian seas. It may briefly be characterized as follows:

Abactinal side with paxillae formed by very long spines not covered by a supradorsal membrane. No actinolateral membrane. Marginal paxillae not enlarged. No oral interradial plates. Spines of the adambulacrals forming together with those of the lower marginals a single transverse series, not united in a web. Usually five-rayed.

Peribolaster Sladen, 1889

Abactinal surface bearing cruciform plates whose lobes overlap, or are connected by intermediate plates, to form an open network of large quadrangular meshes. On the centre of each primary plate is a boss which carries a fascicle of delicate spinelets enclosed in united membranous sheaths. No pedicellariae.

The genus has hitherto been recorded from California, from Chile and from Antarctica.

Peribolaster lictor sp. now Plate 2, Figs. A, B, holotype.

Diagnosis: Body pentagonal-stellate, the rays truncate, flat below, rounded above. Abactinal armature of 3 (occasionally 4) slender spines, each about 2 mm long, in a fascicle, borne on a cruciform or occasionally triradiate plate. The lobes of these plates either overlap or less frequently overlie a small intermediate plate which carries no spines. Inferomarginal plates each carry one flattened spatulate spine. No actinal intermediate plates. Adambulacral plates not exactly opposite inferomarginals, each carrying a transverse row of flattened spines, decreasing in size toward the furrow. Oral plates each with three furrow-spines, the median one largest, and two recurved robust sub-oral spines. Tube-feet biserial.

Material Examined: Eight specimens from 130 fathoms, Station 34, Chatham Islands Expedition.

Holotype: In the Canterbury Museum, R 22 mm, r 9 mm.

Remarks: The species is easily distinguished from the other species with biserial tube-feet by having a total of five oral spines, of which two are sub-oral. In P. macleani Koehler there are four oral spines, one of them being sub-oral, and in P. biserialis Fisher there are four oral spines, all of them furrow-spines. In regard to the flattened or spatulate character of the inferomarginal spines P. lictor approaches P. macleani; the latter is an antarctic form. Peribolaster lictor is so called in reference to the bundles of rod-like spines which it carries.