Mezium namibiensis sp. nov. and other Gibbiinae (Coleoptera, Ptinidae) from the Muséum d’Histoire naturelle de Genève. - Mezium namibiensis sp. nov. is described from a cave in Namibia (S.W. Africa); this new species belongs to the collections of the Muséum d'Histoire naturelle de Genève and it is related to M. gracilicorne and M. andreaei, both described by Pic from South Africa. In addition, a checklist including interesting collecting data of other Gibbiinae belonging to the same museum is presented.