Distribution of two morphologically and ecologically related species of predatory phytoseiid mites of the genus Amblydromella (A. pirianykae and A. recki) in a zone of their natural intergradation (mountain ridge Donetsky Kriazh in the east of Ukraine) is studied for the first time. The list of plants populated by both predators is given. Consistent patterns of mite distribution on life forms of plants are determined biotopical fidelity on the basis of the coefficient. Very rarely, A. pirianykae and A. recki mites simultaneously populate the same plant organism (only 1.6 % of all samples) which can be attributed to the partially resolved antagonistic relationships. Th e basis of the antagonism is, in the first place, similarity of food preferences of the predators that, in principle, occupy the same ecological niche. Dramatic finale of this confrontation is the elimination of one of the species which has no distinct advantage in the specific conditions of a local microhabitat.