Abstract:

The present study was the first report on the major taxa of Antarctic heterotrophic nanoplankton-choanoflagellates(Acanthoecidae) from Great Wall Bay, Antarctica in austral summer. Eleven species of seven genera of choanoflagellates were recorded. This paper showed the observation results of morphology and fine-structure of each species by SEM, as well as discussion on each species' geographical distribution in the world's waters. Eleven species were: Acanthocorbis unguicidata, Bicosta spinifera,Calliacantha natans,C. simplex, Crinolina aperta, Diaphanoeca multiannulata, D. pedicellata, Parvicorbicula circularis, P. so-cialis, Pleurasiga orculaeformis aff. and Pleurasiga sp. . P.orculaeformis aff. was the first record in Antarctic waters. D. multiannulata was limited in Antarctica. Except D. multian-nulata and Pleurasiga sp. ,other nine species were the cosmopolitan. B. spinifera,C. aperta, D. multiannulata and P. circularis were the dominant species of choanoflagellates in Great Wall Bay in austral summer.