Two new species of Trichomerium (Trichomeriaceae, Chaetothyriales) from Guizhou Province, China

Trichomerium is a genus of foliar epiphytic fungi that resemble sooty molds and are commonly found on the surfaces of living leaves. Species within this genus are characterized by dark, intricately interwoven hyphae and ascomata bearing setae. Two novel species forming sooty coating colonies, namely Trichomerium guiyangense and T. xishuiense, were discovered in Guizhou Province, China.

These taxa are morphologically distinct and were formally identified through comprehensive morphological characterization and multi-gene phylogenetic analyses based on two genetic loci (LSU and ITS rDNA). The taxonomic descriptions are supported by detailed illustrations and a phylogenetic tree elucidating the placement of the newly described species. This study enhances the understanding of the taxonomic diversity within Trichomerium and refines its species delimitation and systematics by contributing significant morphological and molecular evidence, expanding the known diversity of this genus in China, and providing new insights into its phylogeny and taxonomy.