SYSTEMATICS OF SOME ANTARCTIC IDMIDRONEA AND EXIDMONEA (BRYOZOA, CYCLOSTOMATA)

Descriptions are given of seven Antarctic species of cyclostome bryozo ans belonging to the genera Idmidronea and Exidmonea, of which I. frau dulenta, I. pellucida and E. arcuata are new. The gonozooids of I. pse udocrisina Borg are described for the first time, and all species are newly illustrated using SEM. The large sample size available has permi tted particular attention to be given to intraspecific variability, es pecially of the ooeciostome which is shown to be more variable than ha s been previously acknowledged.