Revision of the fungus-farming ant genus Mayr (Hymenoptera, Formicidae, Myrmicinae).

The genus Mayr (Formicidae: Myrmicinae: Attini) is a Neotropical group of fungus-farming ants known for its problematic taxonomy, caused by low morphological variability across the species, vague and old species descriptions, and an outdated and incomplete key published in 1916. Recent molecular studies revealed that is the product of a rapid recent radiation, with a divergence date of 4.3 million years ago. Here we present a comprehensive taxonomic revision of the genus based on morphology and a recently published molecular phylogeny. We discuss and illustrate morphological characters for workers, males, queens, and larvae. We report 18 standard morphological measurements and 5 indices for 529 workers, 50 queens, and 39 males, which we employ in morphometric analyses. The revised genus comprises eleven species, including three new species, here described as , , and We also redescribe Wheeler, Borgmeier, Wheeler, Forel, Mayr, Forel, Emery, and Forel. The number of recognized species (11) is lower than the previously recognized 19 species and 3 subspecies. The following species and subspecies are synonymized: under [= Forel , Wheeler , and Forel ]; under [=S. Weber ]; under [= Santschi , Santschi , Weber , Weber , Forel ]; under [= Forel , Wheeler , Weber ]; and under [= Weber ]. We provide a key to species for the worker caste and information on the geographic distributions of all species.