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Echinoderms from Southern New Zealand

Family Temnopleuridae — Pseudechinus Mrtsn. 1903

Family Temnopleuridae
Pseudechinus Mrtsn. 1903

Pseudechinus huttoni Benham, 1908

  • Station NGH 2; seven tests.
  • Ruapuke oyster beds, Foveaux Strait, 12 fathoms, February, 1951; coll. B. M. Bary; two specimens.
  • Off coast of Canterbury, between Moeraki and Timaru, 40 fathoms, January, 1951; coll. P. M. Ralph; three specimens.
  • Off Otago coast, between Moeraki and Taiaroa Head, 40 fathoms, November, 1951; three large specimens.

Pseudechinus albocinctus (Hutton, 1872)

  • Alert stations: 11, three dead tests; 13, ten dead tests of very young individuals; 23, three immature living specimens.
  • Ruapuke oyster beds, Foveaux Strait, 12 fathoms, February, 1951; coll. B. M. Bary and C. A. Fleming; three specimens.
  • Off Otago and Canterbury coasts, between Taiaroa Head and Timaru, 40 fathoms, January and November, 1951; coll. P. M. Ralph; six specimens.

Pseudechinus novae-zelandiae (Mrtsn., 1921)

  • Alert stations: 11, two dead tests of young individuals; 13, five young dead tests; 23, five young living specimens; 24, one young specimen.page 34
  • Ruapuke oyster beds, Foveaux Strait, 12 fathoms, February, 1951; B. M. Bary; one specimen.
  • Off East Canterbury coast, between Timaru and Moeraki, 40 fathoms, November, 1951; P. M. Ralph; two large specimens.

It would appear that in the southern part of New Zealand the three species of Pseudechinus occur side by side. In the material examined, it was notable that wherever specimens were taken in either young or old stages, large forms or small, dead or living, the particular character, whatever it might be, applied pretty well equally to all three species. A consistently small size of individuals from the Fiords is notably in contrast with an equally consistent occurrence of large specimens off the east coast of the South Island. In both the New Golden Hind and the Alert dredgings, there was a surprising preponderance of dead tests of immature and even post-embryonic individuals in the Fiords region. Some had annelid tubes or small corals growing on them. The reason for this is not clear. Some specimens, especially from station NGH 2, had adhering mud, as if from a soft bottom—a habitat not frequented by Pseudechinus. On the other hand, Mr. C. A. Fleming, of the New Zealand Geological Survey, informs me (private communication, 1952) that the mollusca from the same station indicate a hard bottom, though the species present are few. It is possible that there are rapid transitions from hard to soft bottom in the Fiords, and that mud frequently overwhelms the hard-bottom communities. Fleming has found analogous sequences in the Castlecliffian strata (Upper Pliocene), hard and soft-bottom communities alternating. This probably accounts for the presence in the Castlecliffian of Pseudechinus in mud marl, a matrix not otherwise to be expected for the genus; the Castlecliffian specimens are small, like those from the Fiords.