Cladocerans of the Alona affinis (Leydig, 1860) group from South Africa

Study of South African populations of chydorid cladocerans in the Alona affinis-group (Anomopoda: Chydoridae) revealed two closely related species, Alona affinis (Leydig, 1860) and a second, previously unknown, species A. martensi sp. n. No significant differences were seen between South African and Eurasian populations of A. affinis sensu stricto. A. martensi sp. n. differs from other species of the affinis-group by a shorter spine on the basal segment of antennal exopodite, and can be distinguished from A. affinis by a number of additional morphological characters. A. affinis is distributed mainly in the East and South regions of the Republic of South Africa, and is less frequented in this region. Confined mainly to artificial water bodies its presence may be human-mediated. A. martensi sp. n. sems to be endemic to the Drakensberg mountains within the borders of the KwaZulu-Natal Province and Lesotho.