A survey of epiphytic yeasts on leaves of selected Mediterranean plant species collected at the 'Arrábida Natural Park' (Portugal) yielded about 850 isolates, mostly of basidiomycetous affinity. Amongst the basidiomycetes, 35 strains showed the following characteristics: production of orange-coloured colonies, ability to produce starch-like compounds, assimilation of D-glucuronic acid and/or inositol, inability to utilize nitrate, and formation of ballistoconidia by many of the isolates. This group of yeasts was assigned to the Tremellales lineage of the Hymenomycetes and was further characterised using a combination of conventional phenotypic identification tests with molecular methods, namely PCR fingerprinting and rDNA sequencing. Eight additional strains presumptively identified as Bullera armeniaca, B. crocea or Cryptococcus hungaricus were also studied. Twenty-eight strains could be assigned to or were phylogenetically related to recognised species of Dioszegia in the 'Luteolus clade', but the 15 remaining strains belonged to other clades within the Tremellales. Ten phylloplane isolates were identified as Dioszegia hungarica, one as D. aurantiaca, another as D. crocea and three others were ascribed to the recently described species D. zsoltii. Seven novel species, viz. Cryptococcus amylolyticus, C. armeniacus, C. cistialbidi, Dioszegia buhagiarii, D. catarinonii, D. fristingensis and D. takashimae, are proposed for the remaining strains that did not correspond to any of the hitherto recognised species.