Phronima novae-zealandiae Powell.

Phronima novae-zealandiae Hutton, Index Faunae N.Z., p. 256, 1904.

This is a common pelagic form often washed up on the sandy beaches of New Zealand. In June, 1911, two specimens were found at Sumner, where Powell's type specimens were captured, and were sent on to me by Professor Park, of Dunedin. In March, Mr. C. Barham Morris, of Oamaru, sent me a mounted slide of a small Phronima taken at Tomahawk Beach, Dunedin. This specimen appeared to be identical with the one referred to P. pacifica Streets by Stebbing in the “Challenger” Reports (p. 1350). As P. pacifica had not been previously recorded from New Zealand, I wrote to Mr. Morris asking if he had further specimens, and in reply was informed that the small specimens were taken along with ordinary large specimens which he considered to be P. novae-zealandiae.

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I find from the examination of one of the large specimens kindly forwarded by him that this identification is quite correct, and it appears almost certain, therefore, that the small specimens taken at the same time are simply immature forms of P. novae-zealandiae. Most of them measure about 4 mm. in length. The “Challenger” specimen, which was taken in the Atlantic Ocean, off Sierra Leone, was “3/10 in.” in length, and was therefore probably an immature form also.

P. pacifica was originally described by Streets from the North Pacific Ocean, and was said to be distinguished from P. sedentaria by the broadly quadrate form of the carpus of the third pair of thoracic feet and by having the carpus of the second gnathopods less produced anteriorly. It was also pointed out that there was a striking resemblance of the smaller specimens of P. pacifica and the corresponding parts of P. atlantica, which is said to be the female of P. sedentaria. It appears, then, that there is some suspicion that P. pacifica is not a distinct species, but perhaps an immature stage.

Unfortunately, I am unable to consult all the literature necessary on this point, but the forms I have seen undoubtedly seem to be the young of P. novae-zealandiae, and if not identical with P. pacifica are extremely