Ecological character displacement predicts that interspecific resource competition results in greater trait divergence between species in sympatry than in allopatry. In this study, we characterize character displacement in 8 species of snail-feeding Acoptolabrus ground beetles (Coleoptera, Carabidae, genus Carabus) in the Far East. Acoptolabrus exhibit divergent feeding phenotypes, including species with a slender forebody for intruding large shells and species with stout heads and mandibles for crushing small shells. Distance measurements (in mm) deposited here are for evaluating body shape variation among 8 Acoptolabrus species.

To evaluate morphological divergence among taxa, vertical and horizontal distances of the head (VH and HH), prothorax (VP and HP), and elytra (VE and HE) of adult beetles (Konuma and Chiba 2007) were measured to the nearest 0.01 mm on digital images of dried specimens using ImageJ ver. 1.49m (Schneider et al. 2012).

The measurement unit is in millimeter.