Ogmocidaris Mortensen, 1921

Ogmocidaris benhami Mortensen

• Mortensen, Th., 1921. Vid. Medd. dansk naturh. For., 73, 151.

Material Examined: Seventy-five specimens from the following deep-water stations: 400 fathoms, off Mayor Island, Bay of Plenty, Dom. Mus. Station B.S.210, 1 large individual (h.d. 30 mm, longest primaries 70 mm), and several juveniles; 290 fathoms, Chatham Rise, Station 59, Chatham Islands Expedition 1954, 1 specimen; 270 fathoms, off Mayor Island, Bay of Plenty, Dom. Mus. Station B.S. 209, 10 specimens; 200 fathoms, S. of Cape Kidnappers, Kotuku Station 5, J. A. F. Garrick, 1 specimen; 124 fathoms, Bay of Plenty, Station N.P.6, 56 specimens; same region, N.P.9, 2 specimens; 113–120 fathoms, off Mayor Island, Dom. Mus. Station B.S.208, 1 specimen.

Mortensen (1921, p. 151) drew attention to the fact that Benham (1909) had confused Porocidaris elegans Agassiz (now referred to the genus Histocidaris) and Ogmocidaris benhami; later Mortensen (1928, p. 76) noted that the erroneous record of Histocidaris elegans from New Zealand rested on this confusion. Whilst identifying echinoderms at the Dominion Museum recently I was surprised to find two specimens of Histocidaris elegans in the collection, one of them labelled "Ogmocidaris benhami", the other "Porocidaris". Both of the specimens were labelled as from "300 miles east of Cape Farewell, in 1,100 fathoms, H.M.S. Challenger". Reference to the Challenger Station list shows that, although a station (No. 165c) was worked "334 miles from Cape Farewell, in 1,100 fathoms", it was not a bottom-sample, and no echinoids or other bottom-dwelling animals are recorded as having been taken. On the other hand, at the preceding station, No. 164, off the coast of New South Wales, a number of specimens of Porocidaris elegans were obtained (the holotype included). Probably, therefore, the specimens at the Dominion Museum were derived from New South Wales, and the error in locality on the labels arose from a previous error in writing 165c instead of 164. It is not known how this Challenger material came to be deposited at the Dominion Museum, but it may be inferred that some exchange was negotiated when the vessel was in Wellington. A large pycnogonid in the museum of the Department of Zoology, Victoria University, is believed to have been acquired from the Challenger in this way.