Cladosporium from caves of the Brazilian savannah (Cerrado) and the description of six new species

Abstract

Caves are important but understudied reservoirs of fungal diversity, particularly for genera such as Cladosporium (Cladosporiales, Dothideomycetes). This study aimed to characterise the richness of Cladosporium species from six caves in the Brazilian savannah (Cerrado) using an integrative approach combining morphology and multi-locus phylogenetic analyses (ACT, ITS, RPB2, TEF1-α, and TUB). To improve species recognition in Cladosporium, selected ex-type strains were studied, for which RPB2 and TUB barcodes were also sequenced. Species were delimited using morphology and phylogenetic inferences, supplemented by the pairwise homoplasy index (PHI) test to evaluate species boundaries. Twenty-three species were identified among 94 Cladosporium isolates. The polyphasic approach resulted in the description of six new species: five in the C. cladosporioides complex (C. carsi, C. lacerdae, C. mambaiense, C. nogueirae, and C. propiciense) and one in the C. sphaerospermum complex (C. mesquitapaivae). Additionally, analyses based on morphology, genealogical concordance phylogenetic species recognition (GCPSR), and the PHI test resulted in the synonymisation of C. ribis and C. speluncae under C. bambusicola, C. brigadeirense under C. puris, and C. marinisedimentum under C. sphaerospermum. Among the previously known species identified, 11 represent new records for cave environments, with C. bambusicola being the most frequent (29.17%). These findings substantially expand the known diversity of Cladosporium in Neotropical caves, highlighting the Brazilian Cerrado as a hotspot of mycodiversity. Furthermore, ACT, RPB2, TEF1-α, and TUB are proposed as the primary phylogenetic barcodes for distinguishing closely related Cladosporium species, particularly within the C. cladosporioides complex. This study further emphasises the necessity of using a polyphasic approach to achieve accurate taxonomic resolution among Cladosporium species, trace their distribution in caves, and help to understand their ecology.