Phylogenetic relationships of human-pathogenic Cladosporium (Xylohypha) species inferred from partial LS rRNA sequences

Abstract

The controversy about the appropriate taxonomic placement of agents of subcutaneous and systemic mycoses in either Cladosporium or Xylohypha, both genera characterized by conidia being produced in dry, acropetal chains, was addressed with partial sequencing of LS ribosomal RNA. Observation of catenate anamorphs in species of Capronia (Ascomycotina, Herpotrichiellaceae), a genus which also has anamorphs in Exophiala, suggested the possibility of a close interrelationship of all human-associated taxa. To test this hypothesis, partial sequences of 43 strains of Cladosporium/Xylohypha were analysed. Human-pathogenic and saprophytic Cladosporium species were found to be phylogenetically distinct from each other and, on the basis of known teleomorph relationships, were considered to be anamorphs of Herpotrichiellaceae and Mycosphaerellaceae, respectively. They should therefore be classified in different anamorph-genera; Cladosporium being restricted to plant-associated species. A relatively large proportion of the Herpotrichiellaceae is presumed to be animal-associated. The black yeast genus Exophiala was also confirmed to be of herpotrichiellaceous relationship. The genus Xylohypha is unrelated.