Variation in the colour pattern of the narrow-headed ant Formica exsecta (Hymenoptera: Formicidae) in European Russia

We determined whether body colour patterns of the narrow-headed Formica exsecta ant can serve as a marker of adaptative strategies in heterogenous environments. The variations in colour were studied in two populations of F. exsecta in central and north western areas in European Russia. A generalised colour scheme of the head and three thorax segments is developed based on a comparative analysis of the colouration of F. exsecta and red wood ants (Formica s. str.). The scheme consists of 23 variants. We found that the colouration of different parts of the body varies independently to a large extent, although a pale (less melanized) head and three thoracic segments often co-occur with paler other parts of the body. We also show that the relationship between colour pattern and body size vary significantly in different complexes. We suggest that these colour variants can be used to study the spatial-temporal phenotypic differentiation of populations and adaptation of ants to microhabitats. The proposed scheme can be used as a convenient tool in future studies to quantify the variation in colour patterns. This scheme should be further tested for its applicability for other species of the subgenus Coptoformica.