Morphological studies of selected taxa in the Cymbellaceae from French Pyrenees including the description of a new species : Delicata couseranensis sp. nov. Lakes and wet rocks in the French Pyrenees are inhabited by diversified diatom communities. Taxa of Cymbellaceae are particularly numerous. Morphological studies using light- and scanning electron microscopy of selected species are presented herein. One of them belongs to the genus Delicata and is described as a new species, Delicata couseranensis sp. Nov. The new species is close to Delicata judaica (Lange-Bertalot et Krammer) Krammer et Lange-Bertalot in morphology but differs in the dimensions, the length/breadth ratio and the number of puncta in 10 µm. The detailed morphology of seven recently described species is also examined: Cymbella perparva Krammer, Cymbella maggiana Krammer, Cymbella simonsenii Krammer, Cymbella neoleptoceros Krammer var. tenuistriata Krammer, Cymbella subhelvetica Krammer, Cymbella lange-bertalotii Krammer and Cymbopleura laeviformis Krammer. The taxonomic affinities of all these taxa are discussed and data on their ecology and biogeography are given.