Tococa is a neotropical genus of small trees and shrubs, composed of about 45 species, 2/3 of which have simbiotic association with ants. The ants inhabit domatia that developes at the base of the leaf blade or the apex of the petiole. Natural history observations and field experiments were carried out in order to study the characteristics of this association. Ants from at least 7 different genera from 3 different subfamilies were found inhabiting the domatia of Tococa. Depending on their behavior, the inhabiting ants can be characterized as timid or aggressive. The different types of behavior are not associated with the host species, but with the surrounding environment. Neither there are co-specific associations between the ants and the different species of Tococa. Ant exclusion experiments in ant-bearing Tococa demonstrated that both timid and aggressive ants protect their host plants against potential herbivores, by both warding off scouts of leaf-cutter ants and removing the eggs of Lepidoptera and Coleoptera. The presence of stem and petiole trichomes seems to be critical for the establishment of ant colonies, since their removal often results in the ants vacating their host plant. Employing a previously obtained phylogeny of the genus Tococa, it was possible to determine that ant domatia, and thus myrmecophytism, have evolved at least twice within the genus. Secondary losses of domatia have also occurred. These losses can be associated with the life history and habitat of the species lacking domatia. The presence of stem pubescence has predated the evolution of ant domatia in both instances within Tococa.

Key words: ant-plants, Character evolution, Melastomataceae, myrmecophytism, Tococa