Morphological and phylogenetic analyses reveal new species of the Fusarium lateritium species complex and Fusarium torreyae species complex (Nectriaceae, Hypocreales) from Hainan Province, China

During a survey of fungi associated with woody plants in Hainan Province, China, two novel Fusarium species were discovered from symptomatic leaves of Castanopsis sp. and Mallotus japonicus. Through morphological examination and multi-locus phylogenetic analyses, the isolate from Mallotus japonicus was identified as a new species within the Fusarium lateritium species complex (FLSC) based on tef 1, tub 2, rpb 2, and CaM sequences, and is described here as Fusarium malloti sp. nov.

In contrast, the isolate from Castanopsis sp. was resolved as a distinct lineage within the Fusarium torreyae species complex (FtorSC), supported by ITS, LSU, rpb 2, rpb 1, and tef 1 sequence data and is described as Fusarium castanopsidicola sp. nov. Both new species are morphologically characterized and phylogenetically distinct from their closest relatives. These findings highlight the significant but underexplored diversity of Fusarium in Hainan and reinforce the necessity of integrating morphological characters with multi-locus phylogenetic analyses for accurate species delimitation in this genus.