First Neotropical record of the association between brown sclerotium-forming fungi and termite eggs in a nest of Coptotermes gestroi (Blattaria, Isoptera, Rhinotermitidae).

Insects and fungi are abundant in many environments, in which facultative and/or obligate associations involving these groups have been established during evolution. In termites, mutualism with fungi is well reported for some termite lineages (e.g., Macrotermitinae). Within some subterranean termite species (Rhinotermitidae), egg-mimicking fungi, also referred to as "termite "balls", are often harbored inside the nest, mixed to the egg piles. Such interaction seems to be advantageous for both partners since the fungi are protected inside the nest while they may serve as an additional food source and also provide cellulases which may be incorporated into the termite digestive process. Although such mutualism has been reported for seven species of Reticulitermes and Coptotermes formosanus, all the samplings were restricted to temperate regions. Here, we provide the first Neotropical record of this termite-fungus association, and the first report for Coptotermes gestroi. The morphological characters of the "termite balls" observed in a C. gestroi nest resemble those already reported for Reticulitermes spp. and the congeneric species C. formosanus. They include a color ranging from light to dark brown, spherical shape, and a reduced diameter (0.23-0.34 mm). Our findings provide new insights into the geographical distribution of the association between termites and sclerotium-forming fungi. Future genetic analyses will be valuable aiming to identify the egg-mimicking fungi associated with C. gestroi and shed light on the evolution of this fascinating symbiosis.