Carolinea 76

54 Carolinea 76 (2018) Despite the low substrate diversity, branches of shrubs may contain a considerably rich lichen community. This is especially true for Gymno­ sporia heterophylla (Celastraceae): We found a total of 19 lichen species living on five thin twigs of this phorophyte, collected from one individual plant and collectively measuring only c. 50 cm. The lifespan of the epiphytes is influenced by the relatively short age of the phorophytes, and is shortened by fire events, thus these species have a higher probability of a shorter lifespan than their rock-inhabiting counterparts. These factors col- lectively contribute to the phenomenon that the epiphytic biota are comprised mainly of species which are able to reproduce and spread rapidly and effectively and therefore are widespread and frequent on trees or shrubs in open landscape. Some are nearly cosmopolites, such as Physcia adscendens , while others are pantropical, such as Parmotrema austrosinense, P. reticulatum, Flavoparmelia soredians, Ramalina celastri, Te­ loschistes flavicans , and Haematomma persoo­ nii . Endemic species are an exception, for exam- ple Dufourea inflata , Teloschistes puber . The epilithic lichen biota of the renosterveld and fynbos vegetation types are unique, in terms of their diversity and levels of endemism. The spe- cies, in particular the members of the dominant genus Xanthoparmelia , tend to have a much more restricted distribution than their epiphy- tic counterparts. Only very few are widespread. Many are endemic to South Africa, mainly the Cape Region, while some show a south African- Australian disjunction (a Gondwanaland distri- bution), as with X . molliuscula . In Australia the genus has a second major center of speciation with very similar species numbers, comprising ca. 170 species (sensu str.) or 250 (sensu lato) respectively, but spread over a much larger area and without a concentration like in Cape Provin- ce. Of 20 completely identified Xanthoparmelia species on our list, eight are known only from the Cape Province, four only from South Africa in wide sense; three are more widespread in southern Africa; two are shared between South Africa and Australasia, one is shared between South Africa and South America, and two are wi- despread over several continents. The fact that a very short collecting trip in a very restricted area of the Renosterveld Reserve pro- vided evidence of 73 lichen species, including eight endemics of the Cape Province, and three lichenicolous fungi (among them one possibly undescribed Arthonia sp.), illustrates that lichens are a valuable part of the plant diversity for which this vegetation type is renowned. The total figure of 73 lichens is not particularly high and reflects the scarcity of large rocks and big trees. In some tropical forests a single tree may have well over 100 species. Special is the high proportion of Xanthoparmelia species endemic to the Cape Province. Acknowledgments We thank very much M artin H eklau (Stuttgart) for his TLC-Analyses, C arlo A rendorf from Cape Nature and C hris M artens (Fynbos Trust) for their help getting an export permit for the samples, J annie G roenewald for accompanying us and assisting with collections. A nd - ré A ptroot (Soest, The Netherlands) kindly identified the Traponora species, E inar T imdal (Oslo) commented on Psora aff. crenata . V. W irth is very grateful for the support by P eter K rcmar (Stanford) for enabling him to stay in the Western Cape and for transporting speci- mens to Germany. Literature A lmborn , O. 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