IDENTIFICATION BY ELECTRON-MICROSCOPY OF MARINE NANOPLANKTON FROM NEW-ZEALAND, INCLUDING THE DESCRIPTION OF 4 NEW SPECIES

The marine nannoplankton of New Zealand were examined for the 1st time by a combination of transmission and scanning electron microscopy. About 50 taxa were found, practically all known also from the Northern Hemisphere. As in this part of the world, the nannoplankton consists mainly of members of the systematic groups Chrysophyceae, Prymnesiophyceae (Haptophyceae), Loxo- and Prasinophyceae and Choanoflagellida. Four new species are described: the prymnesiophytes Chrysochromulina novae -zelandiae and Phaeocystis scrobiculata, the choanoflagellate Bicosta antennigera, and Petasaria heterolepis, a flagellate of unknown affinities. Cells of the latter are covered by a scaly periplast, which contains both unmineralized and mineralized scales, of which the latter are siliceous (as demonstrated by X-ray microanalysis). In the New Zealand material 35 spp. were identified, of which only the coccolithophorid Coccolithus huxleyi and the prasinophyte Pyramimonas grossii were previously found in New Zealand. The remarkable similarity between the nannoplankton of the Northern and the Southern Hemispheres is discussed, based on these findings, and many of the flagellates may be cosmopolitan, possibly occurring in cooler (deeper) water in the tropics. Some of the species recorded from New Zealand may be considered warm-water species (e.g., the choanoflagellate Parvicorbicula pulchella); others are known from cold water only (the unusual coccolithophorid genus Turrisphaera). Many of the flagellates occur in a wide temperature interval.