The distribution of the dwarf succulent genus Conophytum N.E.Br. (Aizoaceae) in southern Africa

摘要

Background: The dwarf succulent genus Conophytum N.E.Br. is one of the most species rich in the Aizoceae. The genus is most closely associated with a region of high floral endemism and biodiversity, the Succulent Karoo biome in south-western Africa.Objectives: To examine the distribution of Conophytum in south-western Namibia and in the Northern and Western Cape Provinces of South Africa.Method: A database comprising 2798 locality records representing all known species and subspecies of the genus Conophytum has been constructed.Results: The genus is primarily restricted to the arid winter-rainfall region of the Northern and Western Cape Provinces of South Africa and south-western Namibia, within the Greater Cape Floristic Region. Whilst taxa are found across all the main biomes in the region (the Succulent Karoo, Nama Karoo, Desert and Fynbos biomes), 94% of Conophytum taxa are found only in the Succulent Karoo biome and predominantly (88% of taxa) within South Africa. Endemism within specific bioregions is a feature of the genus and ~60% of taxa are endemic to the Succulent Karoo. Approximately 28% of all taxa could be considered point endemics. Whilst the genus has a relatively wide geographical range, we identify a pronounced centre of endemism in the southern Richtersveld.Conclusion: The genus Conophytum can be used as a good botanical model for studying patterns of diversity and speciation in the Succulent Karoo biome, the effects of climate change on dwarf succulents, and for informing conservation planning efforts.