A new species of Cladosporium associated with leaves of Allium ochotense in Heilongjiang Province, China

Cladosporium tongheensis sp. nov. was isolated from diseased Allium ochotense leaves displaying characteristic symptoms collected in Heilongjiang Province, China. Morphologically, the novel species exhibits branched, septate hyphae ranging in color from subhyaline and pale brown to distinctly brown, with surfaces smooth or slightly roughened. Conidiophores arise singly, erect, occasionally curved, and originate either laterally or terminally from hyphae.

They are septate, smooth to faintly rough, pale brown to brown in color, occasionally branched, and display notable constrictions and swellings at septal junctions. The conidia are abundant, mostly obovoid, limoniform, or ellipsoid, predominantly aseptate, occasionally possessing one septum, smooth-surfaced, and pale to medium brown. Secondary ramoconidia exhibit shapes varying from cylindrical and subcylindrical to oblong-ellipsoid and oblong.

Their color ranges from pale to distinctly brown, containing between zero and four septa, and typically tapering at the base with pronounced constrictions occurring at the septa. Multi-gene phylogenetic analysis, involving actin (act), ribosomal internal transcribed spacer (ITS) regions and translation elongation factor-1α (tef 1), unequivocally positioned these isolates as a novel phylogenetic lineage with close affinity to Cladosporium basiinflatum, situated within the broader Cladosporium herbarum species complex.

Therefore, combining phylogenetic evidence and morphological data, we propose a novel species named C. tongheensis.