Candida orba sp nov., a new cactus-specific yeast species from Queensland,Australia

A new species of yeast from decaying cladodes of Opuntia cactus, Candida or ba, is described. This species is a member of a four-species clade of cacto philic yeasts. The new species has only been found in one region of Queensl and, Australia, where it was presumably introduced during attempts to eradi cate prickly pear cactus. DNA-DNA relatedness, phylogenetic analysis, physi ological differences, killer-sensitivity profiles and mating reactions esta blish the distinctness of the taxon as a new species. C. orba is most close ly related to Phaffomyces thermotolerans, a species found associated with c olumnar cacti in the North American Sonoran Desert. The type strain of C. o rba, isolated from rotting cladodes of Opuntia stricta in the State of Quee nsland, Australia, is strain UCD-FST 84-833.1(T) (= CBS 8782(T) = NRRL Y-27 336(T) = ATCC MYA-341). Only the h(-) mating type of the species has been r ecovered. The lack of the opposite mating type could be the result of a bot tleneck during its introduction to Australia. The original geographic/host distribution of this species in the Americas is unknown.