Antennal sensilla in an anophthalmic wood-dwelling species, Clinidium canaliculatum, Costa 1839 (Coleoptera, Rhysodidae)

The habit of feeding on slime moulds (Myxomycetes) commonly present in litter or dead wood requires specific morphological adaptations of the mouthparts and sensory structures involved in the search for habitat and food. In this study, the external morphology of antenna and its sensilla were studied using scanning electron microscopy in the saproxylic beetle, Clinidium canaliculatum, Costa 1839 (Coleoptera, Rhysodidae). Their moniliform antennae consist of a scape, pedicel, and nine flagellomeres. We identified seven different types of sensilla, according to their morphological characteristics: two types of sensilla chaetica (sc1 and 2), two types of sensilla basiconica (sb1 and 2), one type of sensilla campaniformia, one type of sensilla coeloconica, and Böhm sensilla. No sexual dimorphism was found regarding antennal morphology and sensilla type and distribution, except for the sensilla coeloconica. The functional role of these sensilla was discussed in relation to their external structure and distribution, and compared with the current knowledge on coleopteran sense organs. Results are basic information for further physiological and behavioral studies to identify their role in the selection of habitat, food, mates and oviposition sites.