Cymbella loescherae sp. nov. (Bacillariophyceae) from First-Order Streams of Southern Brazil

. This paper describes a new species of Cymbella C. Agardh from low-elevation countryside streams of the Serra do in southern Brazil. Cymbella loescherae M. Garcia & D. B. Dutra sp. nov . has as distinctive features the elliptical shape of stigmata, elliptical internal areolae openings, and the presence of areolae of diverse shapes (X, I, Y, zig-zag) located mainly at the valve center on the dorsal and ventral sides. It resembles C. subhimalaspera Jüttner & Van de Vijver which presents about the same metric data set, but differs from it primarily in the number and form of stigmata, and the form of areola internal openings.