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.