Valve morphology of Amphora chilensis Hustedt (Bacillariophyceae)

Plankton and epilithon samples containing Amphora chilensis Hustedt, collected from rivers in Argentina and type material of the species, have been examined using light (LM) and scanning electron microscopy (SEM). This species has been previously recorded as fossil from a desert in northern Chile and as living from a saline lake of the Altiplano Chileno-Boliviano. As a result of this study the description of the species has been expanded and the range of its morphometric parameters has been enlarged. Amphora chilensis is compared with its closely related taxa A. arcus var. sulcata (A.Schmidt) Cleve, A. lineolata Ehrenberg and A. lineolata var. calamae Frenguelli. The main differences concern the raphe path, the appearance of the central area, valve dimensions and ecological preferences.