Clonostachys kasetsartana sp. nov., a novel epiphytic fungus isolated from the mangrove leaves in Thailand.

Two fungal isolates, DMKU-RG2M15ᵀ and DMKU-RG2P11, were isolated from the phylloplane of healthy leaves of the mangrove tree Ceriops tagal (Perr.) C.B. Rob., collected in Chanthaburi Province, Thailand. Their taxonomic placement was investigated using a polyphasic approach based on morphological, physiological and multilocus phylogenetic analyses. Colonies produced primary conidiophores with verticillate branching, bearing hyaline, smooth-walled, oval to ellipsoidal conidia. Phylogenetic analyses based on a combined dataset of the internal transcribed spacer region, the large subunit rRNA gene, translation elongation factor 1-α, β-tubulin and RNA polymerase II second-largest subunit resolved the two isolates as a distinct and well-supported monophyletic lineage within the genus Clonostachys. Phylogenetic analyses showed that the two isolates are closely related to Clonostachys mangrovei, Clonostachys viticola and Clonostachys reniformis. Morphological and physiological comparisons further distinguished the isolates from their closest relatives. The congruence between phylogenetic and phenotypic data supports the recognition of the two isolates as representing a distinct species. Accordingly, both strains are proposed as a novel species of Clonostachys, for which the name Clonostachys kasetsartana sp. nov. is introduced.