In East Africa Gamasellus are соmmоп inllabitants in the leaf litter and moss of montane forests and tlle moorland above tl1e forests. Тhree species from tlle Uluguru Mts., Tanzania, G. muscOS1tS, G. morogoroe?Zsis and G. ulugurue?Zsis, are described as new. G. pyriformis Berlese from Кепуа is redescribed with tlle male being reported for tl1e first time. Two Gamasellus which differ from G. ulugurensis in size, habitat and form of the male sperm transferring structure are determined to Ье distinct species but not formally described. Altitudinal replacement in mites is briefly discussed.