NEW SPECIES DOUBLE THE DIVERSITY OF ANAEROBIC CILIATES IN A SPANISH LAKE

Fourteen species of ciliates, seven of which are new, were found livin g in a sample of anoxic water collected from a small lake in Spain. Th e species belong to all six orders in which anaerobic ciliates have be en described and they include the first anaerobic representatives of t he order Prostomatida. This surprising diversity is probably sustained because it embraces all ciliate feeding types, and because protozoa a re the only important consumers of the diversity of microbes in anoxic habitats. Six of the anaerobic ciliate species have aerobic congeners ; this strengthens the contention that anaerobic ciliates evolved inde pendently from aerobes belonging to several taxonomic groups.