Three new species of oribatid mites belonging to the genus Epidamaeus are described from litter of birch forests and organic debris on soils in central and southern parts of Mongolia. Epidamaeus aokii n. sp. differs from closely related species in the very thick and densely barbed notogastral setae, the large and widely spaced postbothridial tubercles and spinae adnatae, the relatively short and finely barbed sensilli, the ratio in length of the solenidia s to associated setae d of genua I-III, the presence of the enantiophysis E2, the number of the setae on the epimeral region and femur III, tarsus III, and the absence of the propodolateral apophysis. Epidamaeus angustirostratus n. sp. can be distinguished from its congeners by the conspicuously pointed rostrum, the absence of the propodolateral apophysis, the large spinae adnatae, the presence of the anteroventral projection on trochanter IV, the relatively long femur IV, which is far longer than tibia IV, the relatively short trochanter IV, which is much shorter than femur IV, and the length of setae d’, l’ and v’ on genu IV. Epidamaeus tenuisetosus n. sp. is distinguishable from most other known congeners by the absence of tubercles Vp, E2a and E2p from the ventral plate, the extremely minutely barbed prodorsal and notogastral setae, the smal body size, and the number of setae on tarsi I, II and femur III.
Arachnida, Acari, Oribatida, Damaeidae, Epidamaeus, Mongolia, new species.