Adaptation of the Mouthparts in Some Subterranean Cholevinae (coleoptera, Leiodidae)

Moldovan, O. T., Jal`i}, B. & Erichsen, E.: Adaptation of the mouthparts in some subterranean Cholevinae (Coleoptera, Leiodidae). Nat. Croat., Vol. 13, No. 1., 1–18, 2004, Zagreb. Cholevinae are a group of beetles with many cave representatives that are mainly detritivorous or saprophagous. Some species show modifications of the mouthparts on account of their dietary niche, being adapted to a semi-aquatic way of life, or on account of the degree of adaptation to the life in caves. Differences are obvious also among the genera, and cave species that are at the same level of adaptation. The main modifications concern the shape and structure of the different parts, as well as their length and the disposal of hairs, bristles and setae. The adaptation to an aquatic dietary niche has modified the mandibles, which acquired a spoon-like form to bring water near the mouth, the lacinia taking on the role of stirring and the galea of filtering the organic particles with its fine and very dense hairs. The apparent uniformity of the subterranean environmental conditions and of the trophic resources, together with the scarcity of the latter, might mistakenly lead to the conclusion of a one-way evolution for the underground colonizers. The observed differences between the mouthparts of the studied species can be good material for taxonomists, who can include some of these features in their studies, often difficult due to the homogenous morphology of many inhabitants of the underground. As a contribution to the comparative study of the mouthparts at some representatives of cholevin beetles, we can also highlight the effect of adaptation to cave life on the mouthparts and the evidence of a divergent evolution in a relatively constant environment in terms of climate and food input.