The rare Macrothrix tripectinata Weisig, 1934 is redescribed on material from the East Pamirs (Tajikistan) and Tuva (Russia). Adult and juvenile parthenogenetic females and adult males were studied using optical microscopy and SEM. The thoracic appendages and the molar surface of mandibles were investigated in detail. Selected ‘conventional’ diagnostic features are critically reviewed. The importance of characters, rarely used in the systematics of Macrothrix, such as: type of valve reticulation, similarity or dissimilarity in size of the terminal esthetascs of the antennules of females and males, presence of an abdominal projection and reticulation on the postabdomen, presence, length and armature of a male seta on the antennule, are discussed. A key for the Eurasian species of Macrothrix is proposed.