Fragilaria husvikensis sp. nov. (Bacillariophyceae), another Fragilaria species with transapical ribs from Subantarctica
Van de Vijver, Bart; Denys, Luc; Beyens, Louis
A new freshwater diatom, Fragilaria husvikensis, is described from the subantarctic isles South Georgia and Kerguelen. This is the third Fragilaria species with typical diatomoid transapical ribs. It is distinguished from Fragilaria germainii, which it closely resembles and occurs sympatrically, by differences in valve size and outline, a single row of linking spines, higher striae density and a lesser number of girdle elements. The character complex of both F. germainii and F. husvikensis disagrees with that of Diatoma Bory, Distrionella Williams, Fragilariforma Williams & Round and Fragilaria Ehr. sensu Williams & Round. Both species are therefore considered to be placed more appropriately within Fragilaria sensu lato. F. husvikensis is most abundant in small streams with a circumneutral to slightly alkaline pH and a moderate conductivity.