Genus Moina Baird, 1850

Members of this genus were represented by one well defined species, Moina macrocopa (Straus), and by a group of three closely related genotypes in the Moina micrura group. According to the keys of Goulden (1968), all three phenotypes can be identified as M. micrura, but most cladocerologists agree that it is group of species. Evidence for this conclusion was given by Petrusek et al. (2004), who found reproductive isolation and deep divergence at 12S rRNA for populations of M. micrura from Europe and Australia, suggesting the presence of two sibling species. In the case of Mexican material, the three subgroups separated by DNA barcodes show consistent morphological and distributional differences (Fig. 1.4). M. micrura 1 is found in the semi-desert regions of the north, close to the Pacific side, while M. micrura 2 seems restricted to the highlands of the Central Plateau at sites more than 2000 m above sea level. The third group, designated as M. micrura 3, was found at a single northern locality, and shows an intermediate morphology to the other two types. It seems likely that none of these phenotypes are actually M. micrura s. str., described originally from Austria (Kurz, 1874).