Echinoderms from Southern New Zealand
The collections upon which this paper is based number just under one thousand specimens of echinoderms from the off-shore and deeper waters of the southern half of New Zealand. They have been accumulated over the past five years from various sources, the chief of which are summarized below. One area of which our knowledge of echinoderm distribution has long been defective is the inaccessible south-western fiordland coast of the South Island. The relatively extensive collections from that region which are here recorded do much to fill the hiatus. However, new and interesting problems arise—such, for example, as the presence in the fiords of several species otherwise known only from the Northland and Hauraki Gulf coasts, some 700 miles away.
In a paper read before the 1947 New Zealand Science Congress (Fell, 1949), I attempted to assess Finlay's concept of New Zealand marine zoogeographic provinces in terms of echinoderm distribution, and gave lists of apparently stenotopic species for each of the proposed provinces. By that date, the New Golden Hind collections were already in my hands. and I drew upon the evidence they provided in preparing the lists, though without specifying the data upon which the statements were based. That data is now incorporated here, together with page 2 that provided by subsequent expeditions. On revising the lists of species in the light of the new evidence, it is interesting to find that no amendments as yet appear necessary—apart from the addition of species since discovered. Meantime, therefore, the conclusions stated in that paper stand, and may be regarded as an approach to a working hypothesis. Material at present coming to hand from northern waters suggests that the zone of infiltration of Australian-Indo-Pacific echinoderms probably extends farther to the south than seemed to be the case in 1947, so that some adjustment of the boundary of the so-called Aupourian province may become necessary. That, however, is not relevant to the present study, which is concerned only with the southern part of New Zealand. It must also be stated that the holothurians still remain to be reviewed in the light of recent collections, a study at present in the hands of Mr. W. H. Dawbin. This paper is complementary to a similar one on the echinoderms of the sub-antarctic islands of New Zealand (at time of writing still in the press), and it is hoped later to provide a third contribution dealing with echinoderms from the northern waters of New Zealand.
|(1)||The New Golden Hind Expedition visited the south-western fiords early in 1946, collecting echinoderms from thirteen of the stations worked; the collectors were Messrs. H. W. Wellman and C. S. Wright, of the Department of Scientific and Industrial Research.|
|(2)||The Alert (Captain A. J. Black) visited the north-west coast and the fiords regions of the South Island in May, 1950, and again in December, 1951, to January, 1952. Mr. W. H. Dawbin, of Victoria University College, collected echinoderms from twenty-two of the stations, assembling in all 360 specimens representing twenty-six species of sea-stars, echinoids, and crinoids.|
|(3)||The Royal Research Ship Discovery II visited New Zealand in 1950, when, by courtesy of the National Institute of Oceanography, London, two New Zealand zoologists were enabled to observe on behalf of the New Zealand Oceanographic Committee. These were Lieutenant-Commander B. M. Bary and Mr. W. H. Dawbin, at whose request a dredging station was worked over the Chatham Rise (Discovery station 2733). A collection of ophiuroids obtained there by Mr. Dawbin was made available to me by the New Zealand Oceanographic Committee. A large, but fragmentary, Palaeopneustid echinoid, new to the fauna, was also taken; I understand, however, that an unbroken specimen of the same species was retained by the Discovery authorities for study in England, so the record is not discussed in the present paper.|
|(4)||Various small, but valuable, collections have been made on my behalf by Lieutenant-Commander Bary at Stewart Island (also from one station of H.M.N.Z.S. Lachlan); by Miss P. M. Ralph, of Victoria University College, page 3 from the eastern Canterbury and Otago coasts; by Mr. C. A. Fleming, who has secured several blocks of the Cook Strait sea-floor brought up in fishing-trawls, on which were echinoderms (ophiuroids). Mr. F. Abernethy, then of the Phyllis, made large collections of a limited number of species which apparently abound on the muddy, gently sloping shelf which lies east of Cape Campbell.|
In addition to the generous help of the above-mentioned persons, specimens have also been brought in by Mr. J. A. F. Garrick. The generous co-operation of Captain A. Black made possible the Alert collections. I am indebted to Miss M. Wood, of the Royal Society of New Zealand, for facilitating my access to important and rare technical journals; to my wife, who undertook some of the tedious work involved when the mixed station hauls were being subdivided; to Dr. J. G. Gibbs and Mr. W. F. Harris, who identified plant remains in stomach contents; and to the New Zealand Oceanographic Committee for the material from Chatham Rise.
Ecology.—Environmental data have become sufficiently extensive to make it possible to offer a tentative classification of species under a variety of headings. Now that more detailed stratigraphical studies are being undertaken in New Zealand, the zoologist is frequently asked to suggest probable conditions under which fossils, especially Tertiary fossils, existed, using the present as a key to the past. The existing New Zealand echinoderm fauna finds its closest parallel in the late Tertiary strata of this country. Accordingly, some of the recent species of southern New Zealand are here grouped in the following categories, according to (a) physical character of the environment, (b) bathymetrical range. Forms with a marked preference are, of course, likely to be most useful.
Astrotoma waiter, Psilaster acuminatus, Persephonaster neozelanicus, and Spatangus multispinus indicate a mud-bottom in the sublittoral zone.
Astrobrachion constrictum, Amphiura rosea, Amphiura abernethyi, Ctenamphiura dawbini, and Ophionereis novoe-zelandiae tolerate a mud admixture in a sandy or shelly substrate. All are littoral or sublittoral.
Pseudechinus huttoni, Pseudechinus albocinctus, and Pseudechinus novae-zelandiae are littoral forms preferring a hard bottom, either rock or shell-sand detritus. Dead tests only have been dredged from mud admixtures. The latter species occurs in rock-pools and ranges down to 50 fathoms. The other two range from five fathoms to 50 fathoms.
Apatopygus recens, Peronella hincmoac. and Echinocardium cordatum are not known from a hard bottom, preferring a sandy substrate, the latter also tolerating mud admixture, and even mud alone.page 4
The following tolerate a variety of environments except, apparently, mud: Pentagonaster pulchellus, Ophiomyxa brevirima, Ophiomyxa duskiensis, Ophionereis fasciata, Pectinura maculata.
Amphiura hinemoae occurs on any type of sand substrate, but is not yet known from either a hard bottom or from mud.
The following occur in all environments, from hard rock-bottom to soft mud: Amphiura magellanica, Amphiura spinipes, Amphiura alba, Amphipholis squamata, Ophiactis resiliens, Ophiactis profundi, Pectinura gracilis, Asterina regularis, Sclerasterias mollis, Coscinasterias calamaria. Except for Asterina regularis, which is not known from deeper than 15 fathoms, all these species occur through most of the littoral zone, and three of them—namely, Amphipholis squamata, Ophiactis resiliens, and Ophiactis profundi—extend beyond the continental shelf.
Evechinus chloroticus is essentially a hard-bottom form, occurring just below low-water mark. The solitary record given here of test-fragments from 50 fathoms is so contrary to experience that, until living material is obtained from that depth, the record should not be given too much value. The species will occasionally tolerate a soft muddy substrate, as, for example, the former Napier Inner Harbour before it was drained by the 1931 earthquake.