Jaminaea angkorensis gen. nov., sp. nov., a novel anamorphic fungus containing an S943 nuclear small-subunit rRNA group IB intron represents a basal branch of Microstromatales.

In the course of molecular characterization of yeasts isolated from decaying leaves collected in Cambodia, anamorphic yeast strains were detected that clustered with the Microstromatales in molecular phylogenetic analyses of the chromosomal regions coding for the D1/D2 domain of the large-subunit 26S rRNA gene, the small-subunit 18S rRNA gene and the internal transcribed spacer ITS1-5.8S rRNA gene-ITS2. In the trees obtained, the isolates formed a distinct, basal branch of Microstromatales supported with high bootstrap values. As the isolates could not be identified with any known genus, we have described them as Jaminaea angkorensis gen. et sp. nov. (type strain C5b(T)=CBS 10918(T)=CCY 88-1-1(T)). In the chromosomal region coding for the 18S rRNA gene, the type strain of the novel species contained a group IB intron that was similar in location and sequence to introns found in certain species of Exobasidiales and Entylomatales. As no similar introns have been detected in Microstromatales, the new genus might represent a phylogenetic link connecting these three orders.