The subspecies Diaphanosoma birgei lacustirs, was separated from other recorded cladoceran species which were collected from the Delta region, Egypt on certain morphological criteria. This subspecies is distinguished from Diaphanosoma brachyurum and the same subspecies described in populations of America or Europe by Korinek (1981). It is also distinguished from Diaphanosoma birgei recorded in Egypt that was reidentified and described as Diaphanosoma mongolianum. The main taxonomical characters for different species of the genus Diaphanosoma are antennal
setae and spines, marginal spinulation of valves and their inner fold, denticles on sides of postabdomen and the shape of male copulatory appendages.