Multigene phylogeny and morphology reveal two novel zombie-ant fungi in Ophiocordyceps (Ophiocordycipitaceae, Hypocreales)

Ophiocordyceps unilateralis sensu lato is a common pathogenic fungus of ants. The ant behavior manipulation caused by the O. unilateralis species complex has attracted much attention, and several species of the O. unilateralis complex have been described. However, there are likely many unknown species in the O. unilateralis complex. This study describes two new fungi and one known fungus species collected from China and Vietnam. Ophiocordyceps flabellata sp. nov. and Ophiocordyceps lilacina sp. nov. were described based on morphology and phylogenetic evidence from five genes (SSU, LSU, TEF1α, RPB1, and RPB2). Ophiocordyceps flabellata was characterized by an infected Camponotus ant biting onto a leaf, producing multiple fertile cushions exhibiting flabellate cross-section of the ascoma and limoniform conidia. Ophiocordyceps lilacina was characterized by an infected Polyrhachis ant biting onto a leaf, producing lilac stroma and phialides and fusiform conidia. Both morphological observations and phylogenetic analyses supported that the two fungi were distinct species in the core clade of O. unilateralis within the genus Ophiocordyceps. The phylogenetic analysis of the host revealed that O. satoi infected multiple Polyrhachis hosts. In addition, morphological characteristics of O. satoi have been supplemented. Comparing different strains of the same species from different countries revealed not only genetic differences, but also slight differences in the asexual morphology observed in the same species from pure culture and different specimens. This study adds to our knowledge of the pure culture characteristics, morphology, distribution, fungus, and host diversity of this group and provides taxonomic and phylogenetic data to further explore the evolutionary relationship between fungi and hosts.