<i>Ophiocordyceps desmidiospora</i>, a basal lineage within the “Zombie-Ant Fungi” clade

The genus <i>Ophiocordyceps</i> contains the most diverse assemblage of fungi that attack ants worldwide and are remarkably well adapted to the specific ecologies of their hosts. <i>Desmidiospora myrmecophila</i> Thaxt. is closely related to other ant-pathogenic species within <i>Ophiocordyceps</i>, possibly specific to queens, but the sheer infrequency of encounters and previously unsuccessful attempts to culture this fungus has precluded any meaningful assessment until now. A new record of <i>Desmidiospora myrmecophila</i> from Louisiana was found infecting a foundress <i>Camponotus pennsylvanicus</i> queen, the same host species favored by the more common and ubiquitous ant-pathogenic <i>Ophiocordyceps unilateralis</i> clade found in the same geographic locality. To evaluate a long-held assumption that these fungi represent synanamorphs of a single species, we sampled our <i>Desmidiospora</i> specimen along with the local <i>O. unilateralis</i> population for molecular comparison. We are able to present for the first time the in vitro characteristics and morphology of <i>Desmidiospora myrmecophila</i>, as well as a phylogenetic context for this fungus based on combined molecular analysis of representative members of the Ophiocordycipitaceae. Our results place the <i>Desmidiospora myrmecophila</i> lineage within the genus <i>Ophiocordyceps</i>, with a basal affiliation to the <i>Ophiocordyceps unilateralis</i> core clade; thus, in accordance to the “One Fungus–One Name” (1F1N) rule, we propose a new synonym to suppress <i>Desmidiospora</i> in protection of <i>Ophiocordyceps</i>, i.e., <i>O. desmidiospora</i>. These results further implicate this species as an important and quintessential example of cryptic diversity among an already taxonomically diverse and ecologically important group of fungi.