Abstract Minuartia khorassanica is introduced and described as a new species. The species has a limited distribution in E. Iran close to the Afghanistan frontier. Minuartia afghanica Rech. f. from Afghanistan and Pakistan is morphologically related to the new species but it is not known in Iran. The most important differences between the new species and M. afghanica are mainly in the shape of sepals and leaves and pedicel length. Moreover the two species have quite distinct ranges. Minuartia lineata B ORNM. is another relative of the new species differing from it mainly in reproductive characters. The new species is illustrated and compared with M. lineata based on seed and pollen grain data. An identification key to distinguish these three species is given. In addition, Minuartia litwinowii Schischk. from Turkmenistan and adjacent areas in Iran is reduced to the rank of subspecies as M. lineata subsp. litwinowii. Identification key and selected specimens are given for the two subspecies of M. lineata. The distribution map of all taxa is presented

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