Yamadazyma sisaketensis f.a., sp. nov. and Yamadazyma koratensis f.a., sp. nov., two novel ascomycetous yeast species from mushrooms and cocoa leaves in Thailand, and reassignment of Candida andamanensis, Candida jaroonii and Candida songkhlaensis to the genus Yamadazyma

Abstract

Six strains representing two novel ascomycetous yeast species were isolated from mushroom fruiting bodies and cocoa leaves collected in Thailand. Analysis of the internal transcribed spacer (ITS) regions and the D1/D2 domains of the large subunit rRNA gene sequences showed that the six strains were divided into two groups. The first group consisted of four strains (DMKU-SSK46, DMKU-SK1, SCCL3-5 and SCCL19-3), that were closely related to the type strains of Candida conglobata, Candida insectorum, Yamadazyma dushanensis, Yamadazyma mexicana and Yamadazyma riverae, but with 12–14 (2.5–2.9 %) and 28–50 (5.4–8.8 %) nucleotide substitutions in the D1/D2 domains and the ITS regions, respectively. However, two strains (DMKU-KMY40 and DMKU-KO18) of the second group differed from a group of described species, Candida diddensiae, Candida dendronema, Candida germanica, Candida kanchanaburiensis, Candida naeodendra, Candida vaughaniae and Yamadazyma siamensis by 8–15 (1.5–2.8 %) and 45–53 (8.2–9.6 %) nucleotide substitutions in the D1/D2 domains and the ITS regions, respectively. Phylogenetic analysis based on the concatenated sequences of the ITS regions and D1/D2 domains showed that these strains represented two species of the Yamadazyma clade that were distinct from the other related species. Based on the phylogenetic analysis and phenotypic characteristics, these six strains were assigned to two novel species of the genus Yamadazyma, although formation of ascospores was not observed. Yamadazyma sisaketensis f.a., sp. nov., is proposed for the first group (four strains). The holotype is TBRC 17139T (ex-type culture: PYCC 9797). The MycoBank number is MB 849637. Yamadazyma koratensis f.a., sp. nov. is proposed for the second group (two strains). The holotype is TBRC 14868T (ex-type culture: PYCC 8907). The MycoBank number is MB 849638. In addition, it is proposed that Candida andamanensis, Candida jaroonii and Candida songkhlaensis are reassigned to the genus Yamadazyma as Yamadazyma andamanensis comb. nov., Y. jaroonii comb. nov. and Y. songkhlaensis comb. nov., respectively.