René Le Cohu

Cymbopleura pyrenaica sp. nov. (Bacillariophyceae) et d'autres Espèces du Même Genre Rarement Recensées Dans Quelques Lacs des Pyrénées Françaises

Abstract Cymbopleura pyrenaica sp. nov. (Bacillariophyceae) and some other Cymbopleura species rarely observed in some lakes of the French Pyrenees. During a survey of the diatoms from French Pyrenean lakes, a new species of Cymbopleura, Cymbopleura pyrenaica sp. nov. was found. The detailed morphology of this taxon was examined using light and scanning electron microscopy. The new species most closely resembles Cymbella laevis Naegeli, but the absence of apical pore fields places Cymbopleura pyrenaica in the genus Cymbopleura. The most conspicuous ultrastructural feature is the morphological variability of the areolae. Cymbopleura pyrenaica sp. nov. was recorded in several lakes despite its low occurrence and tolerates a wide range of conductivity. A short review of the scarce Cymbopleura species in the investigated lakes was presented.

Étude Morphologique de Quelques Cymbellaceae des Pyrénées Françaises Incluant la Description D'une Espèce Nouvelle : Delicata couseranensis sp. nov.

Abstract 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.

Three new species of Delicata (Bacillariophyceae – Cymbellales) from New Caledonia and further observations on Delicata nepouiana Krammer and D. neocaledonica Krammer

A recent survey of epilithic diatoms in the running waters of the main island of New Caledonia led to the discovery of three new species of Delicata, Delicata pouemboutensis sp. nov., Delicata gobiniana sp. nov. and Delicata karembeui sp. nov. Delicata pouemboutensis is characterized by a strongly convex dorsal side and a low length/breath ratio (3.2–5.0). Delicata gobiniana has an acicular, almost naviculoid outline, with a high length/breath ratio (7.1–8.7). Delicata karembeui has an unusual stria structure for the genus and a valve face with shallow depressions along the dorsal and ventral sides of the valve. Delicata karembeui can be distinguished from other cymbelloid genera by a combination of features including outline, size, raphe course and stria structure. Delicata neocaledonica Krammer and Delicata nepouiana Krammer, so far only described with light microscopy, were also examined and additional scanning electron microscope observations are included.