Black fungi on the integument of leaf-cutting ants (Tribe Attini)

The relationship of Attini ants with their mutualistic fungi and other microorganisms are studied for over 120 years, but the connection with black fungi was recently discovered and so far poorly explored. Major incentive for research in this area took place in 2007 when it was reported that black fungi related to the genus Phialophora could be an active part of the ants symbiosis. Thus, this study aimed to explore the diversity of black fungi on the integument of leaf-cutting ants (Attini tribe), improving the literature with new species, and to clarify its ecological relationship with other attine symbiotic microorganisms. Overall, the main conclusions of the thesis are: i) the community of black fungi in leaf-cutting ants’ integument is diverse. Isolations performed in two collection years revealed unknown species and others first reported in this microenvironment; ii) the pyrosequencing method showed the presence of several uncultured fungi and the remarkable prevalence of Cladosporium on the integument of winged ants; iii) using phylogenetic and morphological analysis, six Xenopenidiella species, one Penidiellopsis species and one genus in the Teratosphaeriaceae family related to the ants are described; iv) actinomycetes, as Amycolatopsis, Pseudonocardia and Streptomyces, associated with the integument of Attini ants are able to inhibit the growth of a broad range of black fungi, including Phialophora species. Therefore, the integument of leaf-cutting ants proved to be a poorly explored substrate containing several unknown species that could play a significant role in the Attini ant symbiosis. The study of black fungi related to ants is still initial but it is promising for understanding the complexity of this microbial environment. (AU)