This paper reports on eriophyoid mites of the genus Aceria Keifer (Eriophyoidea, Eriophyidae) associated with Tamarisk plants (Tamarix spp., Tamaricaceae) in Egypt and South Africa. Three new Aceria species are described: A. aegyptytamaricis n. sp. causing green galls on buds and twigs of Tamarix senegalensis DC. in Egypt, A. noorspoortiensis n. sp. causing bright pink galls on young shoots of T. usneoides E. Mey. ex Bunge in South Africa, and A. benhaiensis n. sp. living under scaly leaves and causing small green galls and deformation of twigs on T. senegalensis in Egypt and T. usneoides (in South Africa). Sequences of three genes, Cox1, D1D2 28S, and ITS1-5.8S-ITS2, were obtained for A. noorspoortiensis n. sp. and A. benhaiensis n. sp. Blastx search for Cox1 sequences of both new species against Aceria from GenBank (a) indicated the sequence AIT38252.1 of Aceria sp. from Tamarix sp. from India as the most similar with 87–90% identity and 55–56% coverage and (b) revealed one codon deletion about 500 bp in the 3′ direction from the Cox1 start codon, which is the first documented case of a codon deletion in the middle part of this gene in Eriophyinae. Additionally, supplementary descriptions of three other Aceria spp. collected from tamarisks in Egypt are given. They are: A. amrini Joshi from big brown galls of T. aphylla (L.) H. Karst. (first record for Africa), A. dioicae (Keifer) from green galls on buds and twigs of T. senegalensis, and A. tamaricis (Trotter) from green galls on buds and twigs of T. senegalensis (first record for Africa).