Cryptococcus depauperatus , a close relative of the human-pathogen C. neoformans , associated with coffee leaf rust ( Hemileia vastatrix ) in Cameroon

The genus Cryptococcus is well known for its two species — Cryptococcus neoformans and C. gatii — that are etiological agents of cryptococcosis, an important fungal disease of mammals, including humans, and which is particularly common in immunocompromised patients. Nevertheless, Cryptococcus is a large and widely distributed genus of basidiomycetes occupying a broad range of niches, including mycoparasitism. One such mycoparasitic species is Cryptococcus depauperatus , which was firstly mistakenly described as a pathogen of scale insects under the name Aspergillus depauperatus . The “Aspergillus” conidiophores were later shown to be basidia of a Cryptococcus and the new combination C. depauperatus was proposed. Additionally, instead of an entomopathogen, the fungus was found to be a mycoparasite growing on the entomopathogen Akanthomyces ( Lecanicillium ) lecanii . Recently, during surveys for mycoparasites of coffee leaf rust ( Hemileia vastatrix ) in the context of a biocontrol project, white colonies covering rust pustules were observed in Cameroon. Upon close examination, instead of a member of the “white colony forming complex” of Ascomycetes, commonly collected growing on H. vastatrix , such colonies were found to represent a basidiomycete fungus with basidia-bearing chains of basidiospores, typical of the genus Cryptococcus . Morphological and molecular evidence was generated supporting the identification of the fungus on rust pustules as C. depauperatus . This is the first record of C. depauperatus from Africa and of its association with coffee leaf rust.