Chaerilus majkusi sp. n. from Malaysia (Tioman Island), C. neradorum sp. n. and C. stockmannorum sp. n. from Thailand are described and fully illustrated with color photographs of live and preserved specimens, as well as of their habitat. They are compared to the species C. cimrmani Kovařík, 2012, C. sejnai Kovařík, 2005, and C. tichyi Kovařík, 2000, which we also illustrate with color photographs of live unpublished specimens. Hemispermatophores of C. cimrmani, C. majkusi sp .n., C. stockmannorum sp. n., and C. tichyi are illustrated and compared, and we also describe the karyotypes of C. cimrmani, C. majkusi sp. n., C. neradorum sp. n., C. stockmannorum sp. n., C. sejnai and C. tichyi. The diploid numbers of chromosomes range from 76 to 186 and the karyotypes show distinct interspecific variability among analyzed species. C. stockmannorum sp. n. (2n=186) possesses the highest number of chromosomes within the order Scorpiones and the class Arachnida.