Plesiobiotic Associations Between Ants: A Common Yet Underreported Phenomenon in the Mediterranean Region?

Among ants, plesiobiotic associations are defined as occasional or regular nesting of heterospecific colonies in close proximity and without any biological interdependence. Habitats with a scarcity of available nesting microhabitats and ecological dissimilarity between the involved species are supposed to favor the frequency of plesiobiosis. In the last review published on this topic, the authors summarized all the plesiobiotic species pairs reported in the literature for the Holarctic region, listing 48 species pairs. On the basis of our field investigation in the Mediterranean island of Sicily (Italy), we are able to report additional 81 plesiobiotic ant-ant species pairs, two associations of three ant species, and four ant-termite pair associations. We suggest plesiobiosis to be severely underreported rather than rare, at least in the Mediterranean region.