Subterranean (endogean) Scydmaeninae are recorded for the first time from Southeast Asia, based on specimens collected from the mineral soil layer in Cambodia and Vietnam. All reported species show morphological adaptations to life within soil, as microor anophthalmy, miniaturization and light pigmentation. The following new taxa are described: Siamites deharvengi sp. nov. (Glandulariini; Vietnam) is the first Siamites species known outside Thailand and the only species of the genus with microphthalmous males; Blefuscudia gen. nov. (Scydmaenini) is morphologically similar to Liliputella known to occur in the Bismarck Archipelago; both genera are blind and wingless; Blefuscudia khmer sp. nov. (type species of Blefuscudia; Cambodia); Blefuscudia bilineata sp. nov. (Vietnam); and Blefuscudia monolineata sp. nov. (Vietnam). Moreover, three species of Cephennomicrus (Cephenniini; Vietnam) are illustrated, representing the first microphthalmous members of this large genus. All these scydmaenines come from karst hills with a limestone ground.