New or otherwise interesting desmid taxa from the Bangweulu region (Zambia). 1. Genera Micrasterias and Allorgeia (Desmidiales)

Background and aims – As for desmids, the Bangweulu wetlands in Zambia have turned out to belong to the most species-rich areas in Africa. Because of the scarce desmid literature dealing with those wetlands the present authors visited the region in question intending to increase our knowledge of African endemic species. Methods – Samples were collected from Lake Bangweulu and adjacent swamps as well as from Lake WakaWaka, a small isolated lake c. 150 km south-east of it. Collection was by squeezing submerged plant material or using a plankton net. Samples were partly immediately fixed for drawing desmid taxa later on, partly taken home alive for photographing and possible culturing. Key results –Two taxa are described as new to science: Micrasterias denboeri and M. radians var. cruxoides . M. truncata var. africana is raised to species level. Two varieties of M. tropica, i.e. var. elegans and var. elongata are split off as separate species. M. tropica var. crassa is recombined to M. robusta var. crassa . The asymmetric taxa M. sudanensis and Allorgeia incredibilis are discussed for their possible relationships. Conclusions – Most of the taxa discussed may be considered African endemics. Some of them, i.e. M. denboeri, M. sudanensis and Allorgeia incredibilis, presumably are even confined to the tropical central part of Africa. Most of the tropical records of M. crux-melitensis in literature probably have to be considered small forms of M. radians rather than to refer to European-North American M. crux-melitensis