Significant Biogeographic Range Expansion of the Social parasite Acromyrmex fowleri Rabeling et al., 2019

Abstract

Five species of social parasites within the leaf-cutting ant genera Acromyrmex and Pseudoatta have been documented. Among these, Acromyrmex fowleri, an inquiline social parasite of A. rugosus, was previously recorded exclusively from the coastal zone of Ilhéus, Bahia, Brazil, where specimens were collected between 1992 and 1996. Despite extensive sampling efforts in the region, no new records have emerged. This study presents a significant expansion in the distribution of A. fowleri, based on a single dealate female collected in 2005 in Miranda, Mato Grosso do Sul, which is located within the Pantanal biome. This record extends the species’ biogeographic range by approximately 1,900 km westward and 600 km southward from Ilhéus. Interestingly, the ecological conditions in the Pantanal biome contrast sharply with those of the parasite’s previously known restinga habitat. The association of collection events with nearby bodies of water suggests that A. fowleri may be attracted to humid microhabitats, which could elucidate the challenges in detecting its rarely sampled sexual forms. Our findings indicate that A. fowleri possesses a broader distribution than previously acknowledged, suggesting that additional specimens may be present in entomological collections throughout the host’s extensive biogeographic range.