Litter as an important resource determining the diversity of epigeic ants in the South-Central Part of Bahia State, Brazil

Abstract

This study evaluates the richness and composition of the epigeic ant fauna in two Caatinga areas (site 1: Brejo Novo and 2: Frizuba) within a transitional region (between the Caatinga and the Decidual Atlantic Forest) in the Municipality of Jequié, state of Bahia, Brazil. Ants were sampled using pitfall traps and Winkler extractor method in 50 randomly chosen points, totalizing a sampling area of 12.5 ha per site. Overall, we identified 60 species helongingto 27 genera. The most speciose genera were Pheidole, Camponotus, and Solenopsis (with five species each) followed by Wasmannia and Cephalotes (four species each). Pheidole sp 1. was the most frequent species (occurring in approximately 60% of the samples). Since site 1 did not possess a litter layer (and therefore could not be sampled by the Winkler extractor) comparisons between the two areas were made using only the data provided by the pitfall-trap method. The Simpson diversity indexes calculated for sites 1 and 2 were 0-87 and 0.89, respectively, and showed no statistically significant differences (p ≤ 0.417). The Jaccard coefficient revealed only 35.5% similarity in species composition between the two areas. The results suggest that the presence of litter contributed to increased species richness (the Winkler method added 28 species in the sum total of species collected) and "shaped" a distinct faunal composition of the area. The present study is the first ant fauna inventory in the region and reveals an unexplored conservation potential for the Decidual Forest and the Caatinga of northeastern Brazil.