Interactions between Cecropia (Urticaceae) and ants (Hymenoptera: Formicidae) along a longitudinal east-west transect in the Brazilian Northeast

Summary. Although the interactions (including mutualism) between Cecropia and numerous ants have been already well documented, biogeographic studies on the distribution patterns of Cecropia with its associated ants have never been conducted in northeast Brazil. This study evaluates: (1) the regional diversity of Cecropia spp. sheltering ants; (2) the diversity of the ants living in these trees; and (3) the species-specific relationships along a longitudinal east–west transect in southwest Bahia. The ants nesting at the apical stem of 521 Cecropia individuals, mostly C. pachystachya (Trecul 1847), were sampled; 437 trees were occupied by ants belonging to 40 species. The commonest ant species was Azteca alfari (Emery 1893). The abundance of Cecropia, as well as the relative frequency of tree occupation, ant diversity, and association between ant species, were higher at lower altitudes, where rainforest vegetation predominates. Cecropia proved to be an important nesting site for various ant species in this ...