Isolation of the symbiotic fungus of Acromyrmex pubescens and phylogeny of Leucoagaricus gongylophorus from leaf-cutting ants

Abstract

Leaf-cutting ants live in an obligate symbiosis with a Leucoagaricus species, a basidiomycete that serves as a food source to the larvae and queen. The aim of this work was to isolate, identify and complete the phylogenetic study of Leucoagaricus gongylophorus species of Acromyrmex pubescens. Macroscopic and microscopic features were used to identify the fungal symbiont of the ants. The ITS1-5.8S-ITS2 region was used as molecular marker for the molecular identification and to evaluate the phylogeny within the Leucoagaricus genus. One fungal symbiont associated with A. pubescens was isolated and identified as L. gongylophorus. The phylogeny of Leucoagaricus obtained using the ITS molecular marker revealed three well established monophyletic groups. It was possible to recognize one clade of Leucoagaricus associated with phylogenetically derived leaf-cutting ants (Acromyrmex and Atta). A second clade of free living forms of Leucoagaricus (non-cultivated), and a third clade of Leucoagaricus associated with phylogenetically basal genera of ants were also recognized. The clades corresponded to traditional taxonomic groups, and were differentiated by ecological habitats of different species.