Cryptic species within Ophiocordyceps myrmecophila complex on formicine ants from Thailand

Abstract

The Ophiocordyceps myrmecophila complex is composed of pathogens specific to ants, found on the leaf litter or buried in soil and produce Hymenostilbe asexual morph. Species in this complex are morphologically highly similar and can hardly be distinguished macroscopically. To date, it has only been observed on formicine ants of the genera Polyrhachis and Camponotus. In this study, observations were conducted in three sites at Khao Yai National Park of Thailand where three new species are proposed. Molecular phylogenies based on the large subunit of the ribosomal DNA (LSU), partial sequences of translation elongation factor 1-α (TEF), and the largest and second largest subunits of the RNA polymerase Π (PRB1 and RPB2) revealed distinct clades separating these new species, namely Ophiocordyceps megacuculla, Ophiocordyceps khaoyaiensis, and Ophiocordyceps granospora. The morphological features of these three new species are clearly different from Ophiocordyceps thanathonensis, a recently described species of the complex, but mostly overlap between these three. However, they are proposed as distinct species based on molecular phylogenetic relationships, genetic distance, and minor morphological characters related to sexual structures.