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Two new species of thermally dimorphic yeast-like fungi has been described.

July 31 2017

Two new species, Emergomyces africanus from the newly created genus Emergomyces and Blastomyces percursus from the existing genus Blastomyces have recently been described.

Karolina Dukik and colleagues from Utrecht and internationally in their study titled “Novel taxa of thermally dimorphic systemic pathogens in the Ajellomycetaceae (Onygenales)” demonstrated species relationships and their specific phenotypes through morphological, phylogenetic and phylogenomic analyses. They clarified generic boundaries of the fungal family Ajellomycetaceae, a family currently comprising the genera Blastomyces, Emmonsia, Emmonsiellopsis, Helicocarpus, Histoplasma, Lacazia and Paracoccidioides and provided the first annotated genome assemblies to support the description of two new species.

The new genus, Emergomyces, accommodates Emmonsia pasteuriana as type species, and the new species Emergomyces africanus, the aetiological agent of the recently reported case series of disseminated infections in South Africa. Both species produce small yeast cells that bud at a narrow base at 37°C and lack adiaspores, classically associated with the genus Emmonsia.

Another novel dimorphic pathogen, producing broad-based budding cells at 37°C and occurring outside North America, proved to belong to the genus Blastomyces, and is described as Blastomyces percursus. The isolates studied were from South Africa and Israel. Blastomycosis is rare in Africa, probably, and it is not clear if the previously reported cases are attributable to B. percursus or B. dermatitidis, as in N. America.

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