Hantzschia fenestrata hust. (bacillariophyta)—hantzschia or nitzschia?

Abstract

The results of a light and electron microscopical study of Hantzschia fenestrata are presented. On the basis of overall similarity it is recommended that H. fenestrata be transferred into Nitzschia, as N. hierosolymitana nom. nov. Various characters, especially cell symmetry and division, are considered in relation to the separation of Hantzschia from Nitzschia. It is concluded that although Hantzschia is a natural group, it can only be defined polythetically: very few character states are both common to all Hantzschia species and limited exclusively to them. However, the behaviour of the cell during division is at present a useful diagnostic character, since although in Nitzschia cells of hantz- schioid symmetry may occur, these never exhibit the only type of division found in Hantzschia, where a hantzschioid cell gives rise to 2 daughter cells also of hantzschioid symmetry. © 1980 British Phycological Society.