Hidden Diversity Behind the Zombie-Ant Fungus Ophiocordyceps unilateralis: Four New Species Described from Carpenter Ants in Minas Gerais, Brazil

Background: Ophiocordyceps unilateralis (Clavicipitaceae: Hypocreales) is a fungal pathogen specific to ants of the tribe Camponotini (Formicinae: Formicidae) with a pantropical distribution. This so-called zombie or brain-manipulating fungus alters the behaviour of the ant host, causing it to die in an exposed position, typically clinging onto and biting into the adaxial surface of shrub leaves. We (HCE and DPH) are currently undertaking a worldwide survey to assess the taxonomy and ecology of this highly variable species. Methods: We formally describe and name four new species belonging to the O. unilateralis species complex collected from remnant Atlantic rainforest in the south-eastern region (Zona da Mata) of the State of Minas Gerais, Brazil. Fully illustrated descriptions of both the asexual (anamorph) and sexual (teleomorph) stages are provided for each species. The new names are registered in Index Fungorum (registration. indexfungorum.org) and have received IF numbers. This paper is also a test case for the electronic publication of new names in mycology. Conclusions: We are only just beginning to understand the taxonomy and ecology of the Ophiocordyceps unilateralis species complex associated with carpenter ants; macroscopically characterised by a single stalk arising from the dorsal neck region of the ant host on which the anamorph occupies the terminal region and the teleomorph occurs as lateral cushions or plates. Each of the four ant species collected - Camponotus rufipes, C. balzani, C. melanoticus and C. novogranadensis - is attacked by a distinct species of Ophiocordyceps readily separated using traditional micromorphology. The new taxa are named according to their ant host.