Introduction

Until now, only two species of Spatangidae have been recorded from New Zealand. These are Spatangus multispinus Mortensen, the first known New Zealand representative, described by Mortensen (1925) from material taken in Cook Strait; and Paramaretia multituberculata Mortensen, 1950, originally recorded from Bass Strait, but subsequently taken off the Chatham Islands (Fell, 1958). The material here recorded considerably increases our knowledge of the New Zealand representation of the family. It has been assembled over a number of years but, owing to some uncertainties in the existing literature on foreign species, the exact disposition of some of the New Zealand forms has for some time remained in doubt, and while this was the case it was deemed inadvisable to report them. A richer material now available makes it possible to take into account individual variation, and accordingly to determine the systematic status of the forms represented. The results show that the New Zealand Spatangidae are related to, or identical with, Indo-West-Pacific species, especially those occurring in Japan, Hawaii, Indonesia and eastern Australia. One anomalous species, Spatangus multispinus is apparently related to the North Atlantic S. raschi, as Mortensen (1925) has already indicated. In determining the relationships of the species of Spatangus here recorded, the conclusions agree more closely with H. L. Clark's (1917) analysis of the genus, than with Mortensen's (1951) more recent treatment, for it would appear that the characters used by Clark are more stable than those stressed by Mortensen; in particular, if the two newly discovered species of Spatangus are placed into Mortensen's key to the genus, they fall in a position far removed from species with which they share numerous characters, whereas under Clark's arrangement, the New Zealand species all fall into sections containing closely comparable species. It must be admitted, however, that the boundaries between the recorded species have probably been defined on an inadequate sample, and that the range of variation in individual species is probably much page 2 greater than hitherto supposed. If, for example, future work shows that the New Zealand species here recognised as entities, are in fact only members of a cline, then it will inevitably follow that some of the Indo-West-Pacific species at present regarded as entities, cannot be maintained as such. Insufficient material is at present available to prove the existence of a cline in New Zealand waters, and accordingly it has seemed desirable to retain the existing method of classification. It is therefore impossible to treat the New Zealand forms as other than distinct species, each one falling in a different section of the genus. These conclusions are summarised in the form of a key to the known extant species from all seas.