Abstract
Water fleas of the family Moinidae Goulden, 1968 (Crustacea: Cladocera) inhabit ephemeral and permanent water bodies. Like other cladocerans, dormant stages of moinids, namely ephippia (modified molt exuvia) containing resting eggs, play a crucial role for their survival and dispersal. However, in contrast to Daphniidae, moinid ephippia are poorly investigated. In this study based on original and previously published data, we summarize information on the ephippia of the genus Moina Baird, 1850 and discuss their value as a source of information for paleoecological reconstructions. In toto, we analyzed more than 140 ephippia and gamogenetic females of recent and fossil populations from different zoogeographical zones and provide descriptions and illustrations for all revealed types of ephippia, as well as brief comments on taxonomy, ecology and distribution of species and species groups to which they were belonged. Our data on the morphological diversity of moinid ephippia cover only a part of the taxa currently described. However, our brief study revealed a remarkably high diversity of ephippial ornamentation patterns relative to other families of Cladocera. Some patterns of ephippial ornamentation are widely distributed and could be found in different zoogeographical zones. Other types seem to have more local distribution. Based on our observations, the structure of ephippia may be valuable for a preliminary brief identification of species groups, especially small-sized micrura-like taxa. Species with peculiar ephippia also were found, but after closer examination, they may represent groups of sibling species. Unexpected records of M. cf. macrocopa made in the Late Pleistocene of North Yakutia demonstrate that this group previously had a broader distribution range in North-Eastern Eurasia, but it subsequently suffered a mass extinction in that area. From the other side, the Old World lineage of M. macrocopa demonstrates expansion of its distribution in the New World. As an important component of freshwater biota of tropical and subtropical regions as well as regions with arid hot climate, moinids may harbor biogeographical vestiges.We hope that our data will serve as a basis for the special search and identification of their remains, as well as for their incorporation into paleoreconstructions for the tracking of different environmental changes.