Abstract
Chara oedophylla was established as a new species after examination of specimens collected by L. Gauthier in Tunisia in 1926, which were kept at the herbarium of Paris. Subsequently, several scientists considered it to be a variety of Chara vulgaris. During fieldwork in northern Tunisia, we found the species close to its type locality (Mogods region). Detailed examination of abundant populations of these plants revealed their particular, specific morphology. Chara oedophylla is characterised by a sejoined arrangement of the gametangia (on different nodes), whereas they are conjoined in C. vulgaris. The antheridia are very large, as is usually the case in dioecious species. In contrast to C. vulgaris, where geminate oogonia are side by side, they are vertically geminated in C. oedophylla. The female nodes bear numerous swollen bract cells, hence the etymology of the species name. Here we provide an emended diagnosis that highlights the differences compared to C. vulgaris in order to maintain C. oedophylla as a valid species. The significance of sejoined gametangia with respect to speciation is discussed.