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The Marine Algal Provinces of New Zealand.
By Miss L. B. Moore, Botany Division, D.S.I.R.
The records considered included Subantarctic Islands specimens from the “Cape Expedition” adding some 27 species to the 125 already known from the Rossian Province, Chatham Island specimens that add some 40 species to the 150 previously recorded from that area, and J. H. Sorensen's collection from Kermadec Islands which raises the number of species from 44 to 66, adds two warm-water genera, Padina and Hydroclathrus, to the flora of the New Zealand Region, and extends the range of the Juan Fernandez species Distromium skottsbergii. With these new records the Kermadec Province has 10 species not otherwise known in the New Zealand Region, the Chatham Province has also 10, and the Rossian 30.
The provinces of the main islands were delimited mainly on species of rocky shores with the boundaries based not on total florula of each province, but on the range of conspicuous and ecologically important species.
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A list showing the restricted range of some 200 selected species was tabled, and the following species were chosen for illustration. In each group the minimum number of species considered to have a similar distribution is given in brackets.
| A. |
Not found south of East Cape, or of Albatross Point on the west coast (39 spp.), e.g.:— |
| a. |
East coast only: Carpophyllum elongatum, Halopteris hordacea (sensu stricto), Perithalia capillaris. |
| b. |
East coast and north of Kaipara Harbour: Xiphophora chondrophylla var. minus. |
| c. |
Both coasts: Cigartina alveata, Pachymenia himantophora (cf. also mangrove). |
Vidalia colensoi extends from Albatross Point to Mahia Peninsula.
Carpophyllum plumosum, chiefly, if not entirely, east coast, reaches Castle Point.
| B. |
Northern, but reaching to or just beyond Cook Strait (15 spp.), e.g.: Pterocladia lucida, Apophloex sinclairii, Caulerpa sedoides, C. hypnoides, C. articulata, Melanthalia abscissa (sensw lato). |
| C. |
Southern, but extending as far north as Albatross Point and East Cape (9 spp.), e.g.: Halopteris congesta, H. funicularis, Chastomorpha darwinii. |
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| D. |
Southern, but extending as far north as Castle Point (5 spp.), e.g.: Caulerpa brownii, Adenocystis utricularis, Macrocystis pyrifera. |
| E. |
Southern, but extending as far north as Wellington (27 spp.), e.g.: Marginariella urvilleana, M. boryana, Desmarestia firma (?), Xiphophora chondrophylla var. maxima. |
| F. |
Not extending north of Timaru and Milford Sound (10 spp.), e.g.: Apophloea lyallii, Pachymenia lusoria, Delesseria crassinervia, Myriogramme crispata, Brongniartella australis, Cladophora pellucida. |
The figure indicates where significant changes in the marine algal vegetation occur, and compares the provinces so determined with the Botanical Provinces of Cockayne, the Faunal Provinces of Powell, and the zones of surface water as figured by Fleming. Chatham Island shows a mixture of northern and southern algae, as would be expected from its position at the convergence of warm and cold waters.
It is not yet clear whether the equivalent of Powell's Auporian Province can be recognized for the marine algae, but if so it would extend at least as far as Bay of Islands and Poor Knights, and would then include some 14 species not otherwise known on the New Zealand mainland.