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Deep-Sea Echinoderms of New Zealand

Family Asteriidae

Family Asteriidae

Sclerasterias Perrier emend. Fisher, 1924

Sclerasterias mollis (Hutton)

  • Asterias mollis Hutton, F. W., 1872. Cat. Echin. N.Z. p. 4.
  • Sclerasterias mollis Fisher, W. K., 1924. Bull. Inst. Oceanogr. 444.

Material Examined: Although more than a hundred specimens have already been recorded from the Cook Strait shelf at depths less than 100 fathoms (Fell, 1952, p. 12), only ten deep-water specimens have been received. This is the first evidence that the species is archibenthal.

200–300 fathoms, Cook Strait, VUZ Station 51, 1 juvenile; 150 fathoms, Cook Strait, VUZ Station 98, 6 specimens; 150 fathoms, Cook Strait, VUZ Station 99, 1 juvenile; 130 fathoms, Chatham Islands Expedition Station 34, 1 specimen; 120 fathoms, off east Otago, Dom. Mus. Station B.S.189, 1 specimen.

Allostichaster Verrill, 1914

Allostichaster insignis (Farquhar, 1895)

  • Stichaster insignis Farquhar, H. Trans. N.Z. Inst. 27, p. 203, Pl. 13 (1).

var. gymnoplax var. nov. Plate 2, Fig. C, holotype.

Diagnosis: Resembling Allostichaster insignis, but differing from the typical form in having the broad supermarginal plates almost completely naked. The only armature they carry is a tubercle at the upper end of the plate, and two or three small pedicellariae. The granulated surface of the superomarginals (diagnostic of Allostichaster) is thus exposed naturally. Three papulae form a triangle between the naked lower ends of adjoining plates. page 20The armature of the inferomarginals comprises two flattened spines. The adambulacrals are as usual diplacanthid, and occasional monacanthid actinal intermediate plates are seen. These features are all illustrated in the figure.

Material Examined: A single individual, R 35 mm, from 120 fathoms, off east Otago, edge of Canyon A, Dom. Mus. Station B.S.189, 14/8/1955, R. K. Dell. The holotype is in the Dominion Museum.

Remarks: The specimen has only five arms, instead of the usual six, and only one madreporite. These characters would have led me to conclude that it is not fissiparous, were it not for the fact that two rays are only half as long as the other three. It is probable that the animal has undergone fission, but has not yet reduplicated the madreporite in preparation for the next division. One further ground for caution before considering that the specimen represents a distinct species is the fact that Benham (1909) records a specimen of A. insignis from off Otago, having the spines "less numerous than in typical specimens"—without more exact details, unfortunately; he also received a specimen with only five arms and no madreporite. The evidence thus seems to favour extending the diagnosis of A. insignis to include gymnoplax as a varietal form. Should it later be found to be a well-defined form, the varietal name will be available for specific ranking.

Cosmasterias Sladen, 1889

The genus is new to the fauna, but proves to be represented by the same species as in Australia. A diagnosis follows:

Abactinal plates forming more or less well-defined longitudinal series. Actinal plates in two or more series, not overhung by spines of the inferomarginals. Adambulacral plates diplacanthid. Large, straight, unguiculate (felipedal) pedicellariae present.

Cosmasterias dyscrita H. L. Clark. Plate 2, Figs. D, E. H.
  • Clark, H. L., 1916. Endeavour Rpt., Dept. of Trade, Customs, Fisheries, N.S.W., 4, p. 71–2, Pl. 29, figs. 1–2.

Material Examined: Fragments of about 3 individuals, from 130 fathoms, Station 34, Chatham Islands Expedition.

Remarks: The holotype of this species was taken by the Endeavour in 200 fathoms, south of Gabo Island, Victoria, and until now no other specimen was known. As Clark has given only photographic illustrations of the whole animal, I am obliged to rely entirely upon his careful description in making the identification. The oral plates (Fig. H) carry four spines, namely an inner and an outer furrow-spine and a proximal and distal sub-oral spine. Small pedicellariae and large unguiculate pedicellariae occur on or beside these plates. The characteristic appearance of the unguiculate (or felipedal, as Verrill and Clark term it) pedicellaria is shown in Fig. D. The armature of the adambulacral plates is illustrated in Fig. E, occasional unguiculate pedicellariae occurring on the furrow margin. Smaller crossed pedicellariae are scattered among the spines. The actinolateral series carry either one or two prominent, coarse spines.