Spatial niche partitioning of two saproxylic sibling species (Coleoptera, Cetoniidae, genus Gnorimus)

Knowledge on ecological requirements of species is a focal point for their conservation, especially if they live in threatened habitat types such as old-growth forests. We predict that habitat requirements shape the spatial niche partition of two sibling species of saproxylic beetles Gnorimus nobilis and Gnorimus variabilis. To test our hypothesis, we conducted a comparative study on the presence and abundance of these chafer beetles in northern Apennines using air-trapping, exploring the effects of altitude and habitat type. We performed our analyses in a study area of 268 800 ha, where we detected nine patches of putatively suitable habitat (13 347 ha), setting a total of 82 air-traps. We collected an unexpected high number of specimens of both species, and found that G. nobilis and G. variabilis are rarely syntopic, having different ecological preferences influenced primarily by altitude, but also by forest type.