Cryptic lineages in the cardiocondyla sl. kagutsuchi terayama (Hymenoptera: Formicidae) discovered by phylogenetic and morphological approaches

Abstract

The taxonomy of ant species in the genus Cardiocondyla is very confused due to the extreme difficulty in separating many species based on morphology alone. In Japan, one group of the species complex Cardiocondyla sl. kagutsuchi has both winged and wingless worker-like (ergatoid) males (dimorphic) whereas others have only ergatoid males (monomorphic). The presence of both groups prompted us to hypothesize that C. sl. kagutsuchi presumably includes several independent species with differences in their male wing morphologies and modes of reproduction. However, whether any species boundary actually exists between the male groups has remained unsolved over the 10+ years since the previous revision of this genus. In this study, using discriminant analysis, we compared the worker caste morphology of this species complex among lineages detected by phylogenetic analyses. In addition, we examined the number of sexuals present in field colonies. Our results revealed the existence of at least three morphological and phylogenetic groups within this species complex.