The assemblage of epigean ants (Formicidae) inhabiting altered patches found in a latitudinal transect of coastal matorral of semiarid Chile.
The aims of the study were to document taxonomically the composition of the assemblage; estimate its species richness, and describe the effect of latitudinal gradient and matorral condition on species relative abundance and species richness of assemblage. The ants were caught with interception traps (pitfall type). The study was conducted between 2008 and 2011. We recorded the presence of four endemic species and one introduced. Maximum R was estimated at six. Solenopsis gayi (Myrmicinae) and Tapinoma antarticum (Dolichoderinae) were the numerically dominant species. We observed an effect of both the latitudinal floor of matorral and the matorral condition on the relative abundance of the species, particularly in the case of endemic species. This effect did no follow neither the latitudinal gradient nor the matorral condition. The ants' responses were species specific, with influence of the study site over that provided by latitudinal gradient and matorral condition. The distribution of estimated R did not show a clear pattern in any of the two cases. We believe that our results show a complex situation derived from the interweaving of influences due both to the historical rainfall gradient and its concomitant effect on vegetation, the current state of matorral, and the severe drought recorded during the study. It is possible that under conditions of mean precipitation or above, the results are different.