New insights into the morphology, taxonomy and biogeography of Bambusina armata (Desmidiaceae, Zygnematophyceae) and morphologically allied taxa

Bambusina armata var. raciborskii is a rare desmid previously reported only from Brazil, Madagascar, and Thailand. This study documents its first record from continental Africa, based on material collected in central Angola. To date, only line drawings of this taxon have been published. In this paper the first photographs (both light- and scanning electron micrographs) are provided, emphasising the importance of this record. Cells from Angola closely resembled a smaller morphotype described from Madagascar. Distinguishing features from the nominate variety include divergent spines and swollen spine bases. This record extends the known distribution of the taxon to continental Africa, emphasising the importance of continued algal biodiversity surveys in underexplored regions, particularly Africa. Based on an intensive review of previously published literature and an analysis of morphological characteristics of B. armata var. raciborskii specimens from Angola, the raise of taxonomical status of B. armata var. raciborskii to species rank is proposed.