Beetles going underground : morphological adaptions linked with subterranean habits

Aims of the present study were: (1) a thorough morphological documentation of the head and thorax of selected representatives of two coleopteran families with subterranean species; (2) to analyze the effects of the environment based on comparisons of external and internal structural features of species from different specific habitats; (3) to evaluate antennal sensillar patterns to test the hypothesis that blind cave-dwelling species possess more extra-optic sensorial structures than their surface-dwelling relatives. The habitats of the selected species include caves, leaf-litter and deeper layers of soil, and ant nests. By combining light microscopy, scanning electron microscopy, histological sections, micro-CT scanning and three-dimensional reconstructions, we conducted comparative morphological studies on 63 coleopteran species (Leiodidae and Staphylinidae). The anatomy of Troglocharinus ferreri (Reitter, 1908) (head and thorax), Bergrothia saulcyi (Reitter, 1877) (head), Claviger testaceus Preyssler, 1790 (head and thorax), Diartiger kubotai Nomura, 1997 (head), Pselaphus heisei Herbst, 1792 (head) was examined and documented in detail (Study I - VII). Skeletal structures, muscles, elements of the nervous systems and glands were studied and compared, and discussed in the context of evolutionary transformations linked with different subterranean environments.