The genus Cladosporium is one of the largest genera of
dematiaceous hyphomycetes, and is characterised by a coronate scar structure,
conidia in acropetal chains and Davidiella teleomorphs. Based on
morphology and DNA phylogeny, the species complexes of C. herbarum
and C. sphaerospermum have been resolved, resulting in the
elucidation of numerous new taxa. In the present study, more than 200 isolates
belonging to the C. cladosporioides complex were examined and
phylogenetically analysed on the basis of DNA sequences of the nuclear
ribosomal RNA gene operon, including the internal transcribed spacer regions
ITS1 and ITS2, the 5.8S nrDNA, as well as partial actin and translation
elongation factor 1-α gene sequences. For the saprobic, widely
distributed species Cladosporium cladosporioides, both a neotype and
epitype are designated in order to specify a well established circumscription
and concept of this species. Cladosporium tenuissimum and C.
oxysporum, two saprobes abundant in the tropics, are epitypified and
shown to be allied to, but distinct from C. cladosporioides.
Twenty-two species are newly described on the basis of phylogenetic characters
and cryptic morphological differences. The most important phenotypic
characters for distinguishing species within the C. cladosporioides
complex, which represents a monophyletic subclade within the genus, are shape,
width, length, septation and surface ornamentation of conidia and
conidiophores; length and branching patterns of conidial chains and hyphal
shape, width and arrangement. Many of the treated species, e.g.,
C. acalyphae, C. angustisporum, C. australiense,
C. basiinflatum, C. chalastosporoides, C.
colocasiae, C. cucumerinum, C. exasperatum, C. exile,
C. flabelliforme, C. gamsianum, and C. globisporum
are currently known only from specific hosts, or have a restricted
geographical distribution. A key to all species recognised within the C.
cladosporioides complex is provided.