The diatom genus Diadesmis in the Crozet and Kerguelen Archipelagos with the description of five new species

The genus Diadesmis (Bacillariophyta) in the Crozet and Kerguelen Archipelagos was studied using light and scanning electron microscopy. Samples were collected from different habitats: lakes, temporary peat-pools, mosses and soils. Ten species have been recorded. The typification of the species Diadesmis arcuata Heiden, described from Kerguelen Archipelago, is reviewed. Five new species are described: Diadesmis comperei, Diadesmis costei, Diadesmis crozetikerguelensis, Diadesmis langebertalotii and Diadesmis subantarctica. The subgenus Paradiadesmis appears to have an unusual structure: the interstriae are quadrangular hollow tubes.Original Abstract: Des investigations portant sur le genre Diadesmis (Bacillariophycees), observe a l'aide du microscope photonique et du microscope electronique a balayage, ont ete realisees dans differents biotopes des archipels de Crozet et de Kerguelen: lacs, mares temporaires, mousses et sols. Dix especes ont ete recensees. Diadesmis arcuata Heiden, decrite a l'origine dans l'archipel de Kerguelen, est reexaminee et typifiee. Cinq especes nouvelles pour la science sont decrites: Diadesmis comperei, Diadesmis costei, Diadesmis crozetikerguelensis, Diadesmis langebertalotii et Diadesmis subantarctica. Les especes appartenant au sous-genre Paradiadesmis ont une structure particuliere: les interstries sont constituees de tubes creux quadrangulaires.