Phylogenetic reconstruction of the genus Purpureocillium based on multilocus nuclear and mitochondrial DNA sequences, with the description of Purpureocillium xinfangense sp. nov. (Ophiocordycipitaceae, Hypocreales) from Southwestern China
Abstract
The phylogenetic relationships within the genus Purpureocillium remain incompletely resolved. In this study, we reconstructed the phylogeny of Purpureocillium using multilocus nuclear and mitochondrial sequence data and evaluated the taxonomic status of a newly collected fungal species from southwestern China. Phylogenetic analyses were conducted using five nuclear loci ( ITS, 18S, 28S, TEF1-α, and RPB1 ) and mitochondrial gene sequences. Morphological characteristics were examined for the newly collected fungus and compared with those of P. lilacinum , P. lavendulum , and P. takamizusanense . Mitochondrial genomes of these four species were also analyzed for genome structure, gene composition, and nucleotide characteristics. Morphological and phylogenetic evidence supported the recognition of a new species, Purpureocillium xinfangense . It was characterized by conidiophores bearing two or three whorls of phialides, predominantly short cylindrical phialides with a mucronate apex, and elongated conidia arranged in chains. Mitochondrial phylogenetic analysis placed P. xinfangense in a distinct lineage with high topological stability. The mitochondrial genomes of all four examined species were circular, whereas the genome of P. xinfangense was approximately four to five times larger than those of the other three species. All four species showed positive GC skew values. Among the 15 protein-coding genes, nad5 was the longest and atp8 the shortest, while tRNA genes ranged from 71 to 87 bp. Although P. xinfangense is currently known from a single collection, its distinctive morphology, rare ant-associated substrate, and concordant support from nuclear and mitochondrial phylogenetic datasets justify its recognition as a distinct evolutionary lineage. These findings expand current knowledge of species diversity and mitochondrial genome evolution within Purpureocillium .