We investigated the regional occurrence and guild structure of tiger beetle species from open areas in Central Amazonian floodplains. Populations of larvae and adult beetles were observed during monthly field excursions from 1997-1999 to reveal life cycles, habitats, diet activity patterns, and other behavioral traits. One of the eight species found in open areas of Central Amazonia is represented by two subspecies. All except one species were found to reproduce in either white- or blackwater floodplains (6 and 4 species/subspecies, respectively). Habitats of larvae and adult beetles, diet activity patterns, as well as life cycles are given for all species. As a result of different life cycles (seasonal temporal segregation), diel activity patterns (diet temporal segregation), (micro-)habitats (spatial segregation), and behavior, intraspecific segregation of larvae and adult beetles was common. Its extent varied between species, ranging from almost complete segregation to partial overlap. Interspecific segregation was extensive. In larvae this was mainly due to different (micro-)habitat preferences (spatial separation). In adult beetles it was related to different life cycles, activity patterns and (micro-)habitats (seasonal, diet temporal, and spatial segregation). In addition, mandible gapes of adult beetles were different in species within guilds. Larvae of solely one or two pairs of species and adult beetles of only two pairs were found to live steadily together. Hence, guild structures showed strong niche separation. Possible implications for a better understanding of coexistence of tropical tiger beetles as well as for mechanisms mediating coexistence in general are discusse
