Remarks about the taxonomical position of Nodularia harveyana Thuret ex Bornet et Flahault (Cyanophyta, Nostocales) growing on soil
Vigna, Maria Susana; Alberghina, Josefina; Belmonte, Cecilia Fernández
Cultures of soil algae were studied with the idea of identifying the autochthonous algal flora in order to apply them as soil improvements in the future. Soil samples were taken in Mercedes, San Luis Province, Argentina. One of the isolated species was a filamentous cyanophyte: Nodularia (Nostocales, Nostocaceae). Due to the differences among taxonomic criteria employed for identifying the species of this genus we decided, as a first step, to study our material at an ultrastructural level. Our material corresponds to the description of N. harveyana Thuret ex Bornet et Flahault but in many aspects it is very similar to N. sphaerocarpa Bornet et Flahault, the akinetes have yellow brown walls in early stages and brown walls in older specimens. Ultrastructural features are similar to N. sphaerocarpa as well, only differing in the arrangement of the thylakoids, which are denser in N. harveyana, making the differentiation of the two species difficult.