Morphometry and eye morphology of three scaritine ground beetles relate to habitat demands and behavioural traits (Coleoptera, Carabidae, Scaritinae)

Abstract Most ground beetles, even of varying sizes, share a similar body shape, but there are species-specific differences and morphological peculiarities that reflect the demands of habitat and niche. Especially morphological characteristics of the compound eye reflect features of the life style of insect species. We investigated the morphometry and eye morphology of three scaritine ground beetles: Scarites ( Scallophorites ) buparius , Forster, 1771, Parallelomorphus laevigatus Fabricius, 1792, and Distichus planus , Bonelli, 1813, living partly overlapping in coastal habitats of Southern Italy. The small eye size indicates that all the three species belong to the “olfactory-tactile hunters”. Life on mobile sands, on shoreline environment and in retro-dune unstable habitats seem to be the driving factors that influenced smaller differences in eye size, ommatidia number, male/female size ratio, flight ability and several behaviour traits. Habitat preferences and behaviour of the three species are discussed in the light of previous literature and an explanation of female-male cooperation of Scarites buparius in nest digging is proposed.