Zombie-ant fungi from western Mexico: six new species in the Ophiocordyceps unilateralis complex (Hypocreales: Ascomycota) and a new host association with Cephalotes ants

The myrmecophilous hirsutelloid fungi of the Ophiocordyceps unilateralis complex are common in tropical forests around the world. They are known as zombie-ant fungi because they manipulate the behaviour of ants, since infected ants are forced to move to specific sites in the forest, with optimal environmental conditions for the development of the fungus sporocarp or sporome and the release of the spores. Once there, the ants grab to the substrate with their mandibles, die, and their body becomes a source of nutrients for the fungus. Most of the species of the O. unilateralis complex have been described from the Neotropics and the East and Southeast Asia. However, it is likely that there are still many unknown species due to the diversity of their hosts and different specific associations. In this study, we describe six new species of the O. unilateralis complex from western Mexico: O. camponoti-striati , O. cephalotiphila , O. deltoroi , O. haraveriensis , O. jaliscana , and O. pseudocamponoti-atricipis , based on morphological characters, phylogenetic analyses of DNA sequences (18S, TEF1 , RPB1 , and RPB2 ), and ecological data. We found the following host associations: one fungus – one ant, two fungi – one ant, and one fungus – two ants. Furthermore, we confirmed the host species of the ant genera Camponotus and Colobopsis ( Formicinae ) based on morphological characters and COI sequences, but we also found two species of Cephalotes ( Myrmicinae ) susceptible to fungal attack, challenging the paradigm that the O. unilateralis complex is a specific parasite of Camponotini ( Formicinae ) ants. This study provides insights into the evolution and host range of the Ophiocordyceps unilateralis complex in Mexico.