Candida mesorugosa sp. nov., a novel yeast species similar to Candida rugosa, isolated from a tertiary hospital in Brazil.

Candida rugosa is a yeast species that is emerging as a causative agent of invasive infection, particularly in Latin America. Recently, C. pseudorugosa was proposed as a new species closely related to C. rugosa. We evaluated in this investigation the genetic heterogeneity within the C. rugosa species complex. All clinical isolates used in this study were identified phenotypically as C. rugosa but were genotypically different from the C. rugosa type, ATCC 10571. RAPD marker analysis revealed less than 83% similarity between our clinical isolates and the C. rugosa type strain. The D1/D2 region sequences of our clinical isolates showed 98% identity with C. rugosa but only 94-95% identity with C. pseudorugosa. The ITS rDNA sequences of the Brazilian isolates showed 91% identity with the C. rugosa ATCC 10571 ITS sequence. Network and Bayesian analyses of ITS and housekeeping gene sequences separated our clinical isolates into different branches from C. rugosa type strain. These differences are sufficient to reassign our isolates to a distinct species, named C. mesorugosa.