The oribatid mites Dissorhina bulganensis sp. nov. and Ceratozetoides aokii sp. nov. are described from Mongolia. D. bulganensis sp. nov, is distinguished from the other known congeneric species in having a pair of heavily pigmented longitudinal ridges anteriorly of lamellar costulae between lamellar setae, two pairs of strongly sclerotized ridges on the interlamellar region and a pair of weakly sclerotized ridges along the lateral margins of the prodorsum. C. aokii sp, nov. differs from closely related species in the well-developed and relatively wide head of the sensillus, the insertions of the interlamellar setae, which are located under the anterior margin of notogaster, and the relatively narrow lamellae.