ABSTRACT
Mites of the family Unionicolidae were collected from the freshwater bivalves Caelatura aegyptiaca and Unio abyssinicus (family Unionidae). Two new species of unionicolid mites namely Unionicola tetrafirrcatus and Unionicola difitrcatus were collected and described by means of seaming electron microscopic study , The adults of U. tetrafurcatus were found in the mussels Caelatura aegyptiaca and Unio abyssinicus, while those of U. difirrcatus were present only in the mantle cavity of the latter mussel. The occurrence of U. tetrafurcatus in the former host was slightly lower than in the latter one. The diagnostic and specific characters of the two species were compared with other species from the same genus. The females of the two mite species were always more abundantthan their males. The specific names of the two species were proposed in reference to number of - the terminal lateral clawlets, being 4 and 2 in the first and second mites respectively.