EUNOPHORA GEN. NOV. (BACILLARIOPHYTA) FROM TASMANIA AND NEW-ZEALAND -DESCRIPTION AND COMPARISON WITH EUNOTIA AND AMPHOROID DIATOMS

A new raphid pennate diatom genus, Eunophora, and three new species ar e described from highland lakes and streams in Tasmania and New Zealan d. Eunophora tasmanica and E. indistincta are only found in Tasmania; E. oberonica and a fourth species (Eunophora sp. I) also occur in New Zealand. The presence of polar rimoportulae in E. tasmanica and E. obe ronica, the relatively simple structure and arrangement of the raphe s ystem and the shia pattern indicate that Eunophora belongs to the subc lass Eunotiophycidae. However, it differs from the other genera in thi s subclass in the amphoroid symmetry of the cells, the length of the r aphe slits and the non-coaxial internal central raphe endings; also un usual are the position of the raphe on the valve face instead of on th e ventral mantle and the presence of many small discoid or band-like c hloroplasts. Eunophora may represent a link between the Eunotiophycida e and the amphoroid genera of the Bacillariophycidae. Eunophora is cha racteristic of dystrophic to (ultra-)oligotrophic lakes and appears to be restricted to the Southern Hemisphere. The four species display a characteristic distribution in Tasmania: Eunophora tasmanica is common and widespread in all highland lakes, E. oberonica occurs mainly in t he dystrophic western lakes, while E. indistincta and Eunophora sp. I were found mainly in intermediate lakes along the limnological corrido r between the western dystrophic lakes and the eastern oligotrophic la kes.