The paper presents a new method for identifying indicator species and species assemblages that characterizes groups of sites. The method combines species relative abundance with its relative frequency of occurrence in various site groups, creating a symmetric indicator index. This index is maximized when all individuals of a species are found in a single site group and when the species occurs in all sites of that group. The statistical significance of the species indicator values is evaluated using a randomization procedure. Unlike TWINSPLAN, the new method's indicator index for a given species is independent of other species' relative abundances and does not require the use of pseudospecies. The method is applicable to any hierarchical or non-hierarchical classification procedure and provides criteria for comparing typologies, identifying where to stop dividing clusters, and highlighting main levels in hierarchical site classifications. The paper uses a dataset of carabid beetle distributions in open habitats of Belgium to illustrate the method, demonstrating its ability to identify characteristic species and species assemblages at different hierarchical levels.The paper presents a new method for identifying indicator species and species assemblages that characterizes groups of sites. The method combines species relative abundance with its relative frequency of occurrence in various site groups, creating a symmetric indicator index. This index is maximized when all individuals of a species are found in a single site group and when the species occurs in all sites of that group. The statistical significance of the species indicator values is evaluated using a randomization procedure. Unlike TWINSPLAN, the new method's indicator index for a given species is independent of other species' relative abundances and does not require the use of pseudospecies. The method is applicable to any hierarchical or non-hierarchical classification procedure and provides criteria for comparing typologies, identifying where to stop dividing clusters, and highlighting main levels in hierarchical site classifications. The paper uses a dataset of carabid beetle distributions in open habitats of Belgium to illustrate the method, demonstrating its ability to identify characteristic species and species assemblages at different hierarchical levels.