Severe selectivity by extreme environments was investigated in mitosporic fungi with regard to their adaptive responses to high temperature, and to high levels of sunlight and evapo-transpiration. A homogeneous group of graminicolous dematiaceous hyphomycetes was removed from sand dunes in the torrid climate of the Namib Naukluft Park, from arid, clayey soil at Etosha pan and from calcareous crusts in the Namib Desert Park: all of them produce darkening conidiophores and deeply pigmented spores. The size and colour of reproductive structures were recorded and compared with bibliographic data. Results are consistent with a uniform morpho-functional response by these fungi to stress conditions. Keywords: Namibia desert, extreme environments, stress-tolerant mitosporic fungi.