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Deep-Sea Echinoderms of New Zealand

Crossaster Mueller & Troschel, 1840

page 17

Crossaster Mueller & Troschel, 1840

A single row of marginal paxillae. Actinal intermediate plates extending only part of the way along the arm.

Crossaster japonicus (Fisher). Plate 2, Fig. F.
  • Solaster japonicus Fisher, W. K., 1911. Bull. 76, U.S.N.M., p. 330.
  • Crossaster japonicus Djakonov, A. M., 1950. Morskie Zvesdi Morei S.S.S.R., p. 74, Fig. 25.
  • Crossaster multispinus Clark, H. L., 1916. Endeavour Rpt., Dept. Trade and Customs, Fisheries, N.S.W. 4, p. 66–7, Pl. XVIII, Figs. 5–6.

Material Examined: Seven specimens, from the following stations: 320 fathoms, Chatham Rise, Station 58, Chatham Islands Expedition, 2 specimens; 280 fathoms, Chatham Rise, Station 7, Chatham Islands Expedition, 2 specimens; 220 fathoms, Chatham Rise, Station 6, Chatham Islands Expedition, 2 specimens; 50–200 fathoms, Cook Strait, VUZ Station 54, 1 specimen.

Remarks: Fisher (1911) did not figure his material, but his description agrees extremely well with my material, save only that all my specimens have 11 rays, as against 10 or 9 for his. There are 28–29 marginals, separated by less than their own width in a regular series, their spinelets numerous (about 30), the peripheral spinelets shortest, all spinelets shorter than the adambulacral ones. The adambulacral armature comprises a furrow-series of about 9 webbed spinelets and a subambulacral series of 7 webbed spinelets, the latter rather longer than the furrow-series. In my material the spinelets are more closely united in the web than Djakonov (1950) shows in his East Siberian material, but this is possibly due to difference in mode of preservation. The oral plates have about 15 webbed marginal spinelets and about 9 webbed suboral spinules.

H. L. Clark (1916) has described C. multispinus from 150–230 fathoms off Tasmania, on the basis of four specimens, all of them 11-rayed like the New Zealand form. In general appearance the Tasmanian species resembles the New Zealand one, but the number of spinelets is less (6–8 furrow-spines, 7–9 subambulacral spines). The oral armature is similar. There are only about 16 marginal paxillae. Clark's material comprised smaller individuals than mine, R 40 mm, r 20 mm. as against R 85 mm, r 42 mm in a typical specimen from Chatham Islands Station 7. I believe therefore that the differences are due to age, and that the New Zealand and Tasmanian forms will be found to be identical, and that all should be referred to Fisher's C. japonicus, which is evidently a wide-ranging Pacific species.

Colour: The Cook Strait specimen, according to notes made from life by Professor L. R. Richardson, was orange-pink. The specimens from Station 6 of the Chatham Islands Expedition were a marbled translucent white and pink, when observed alive by Mr. G. A. Knox. All are faded to dull fawn-grey in alcohol.