Review of the principle species of fragilariales (Bacillariophyta)in the Kerguelen Islands

Ten species, six of which were previously placed in the genus Fragilaria, w ere examined, mainly by electron microscopy. Fragilaria germainii Reichardt and Lange-Bertalot is transferred to Diatoma, and Fragilaria alpestris Kra sske is transferred to Staurosirella. In Fragilaria capucina Desmazieres, o ne or two rimoportulae are present. In Staurosirella, new details are added concerning the structure of the aerolae; externally, they are multiseriate . Staurosirella pinnata (Ehrenb.) Williams and Round shows an original feat ure: internal "bridges," perforated by very tiny pores, together join the s triae placed on each side of the sternum; moreover, these pores give a part icular structure to the striae. In Staurosirella leptostauron (Ehrenb.) Wil liams and Round, the valvocopula is a closed band with a septum, which is n ew for this genus. Several species show spinose and nonspinose valves; cons equently the presence or the lack of spines does not seem to be an appropri ate criterion to distinguish two species.