Clypeal excision in Tapinoma Förster, 1850 ants is adaptive (Hymenoptera: Formicidae).

Abstract

Evidence is presented that the median clypeal excision in the dolichoderine ant genus Tapinoma Förster, 1850 is a rare adaptive trait improving the protrusion of mouthparts for better exploitation of food or water sources located in narrow cleft spaces. The problem of getting access to food from, for example, narrow tubes of nectaries becomes more serious with increasing worker head width. A regression analysis of species-specific means in 16 Westpalaearctic Tapinoma species shows that the relative depth of clypeal excision grows significantly with head width in the interspecific comparison (p<0.001). Similar relations are also indicated on the intraspecific level for all species with the regression functions being significant on the p<0.025 level. The clypeal cleft allows a sliding of the glossa and dorsomedian crests of the labial galeae in dorsofrontal direction.

Keywords

Functional morphology, adaptive phenotypic trait, foraging biology, morphometry.