Diversity of the subgenus<i>Disparalona</i>(<i>Mixopleuroxus</i>) Hudec, 2010 (Crustacea: Cladocera) in the New and Old World

During the last three decades, strong progress was made in the taxonomy of the family Chydoridae (Crustacea: Cladocera), and the results of these revisions have become a valuable confirmation of the non-cosmopolitanism in the cladoceran distribution. But, to date, delineation between several chydorid genera (Pleuroxus Baird, 1843, Picripleuroxus Frey, 1993, Alonella Sars, 1862 and Disparalona Fryer, 1968) has been intuitive rather than based on careful diagnostics. Disparalona is a cladoceran genus with a complicated and confused taxonomy. We compiled a checklist of all formal taxa belonging to this genus in current understanding. Our study comprises a taxonomic revision of the North American, African and East Asian populations of D. cf. hamata with the aim of clarifying their species and generic status. We redescribe D. hamata (Birge, 1879) based on material from North America and D. chappuisi (Brehm, 1934) based on material from Africa. The latter is common in tropical–subtropical Asia, with a distribution range reaching the Far East of Russia. The second taxon from Africa is provisionally identified as D. cf. striatoides (Šrámek-Hušek, 1946), which was described initially from the Czech Republic. Further comparison is needed for a final conclusion on conspecifity of European and African populations provisionally placed to this taxon. At the current level of knowledge Mixopleuroxus Hudec, 2010 must be accepted as a subgenus of the genus Disparalona. The diagnoses of Disparalona s. str. and D. (Mixopleuroxus) are provided. Disparalona s. str. includes D. ikarus Kotov and Sinev, 2011, D. leei (Chien Shing-ming, 1970), D. rostrata (Koch, 1841) and D. smirnovi Sinev, 2015, while D. (Mixopleuroxus) includes D. hamata, D. chappuisi and D. striatoides. D. leptorhyncha (Daday, 1905) and D. caudata Smirnov, 1996 are not described adequately, but they also probably belong to the latter subgenus. The status of D. acutirostris (Birge, 1879) must be clarified in the future.www.zoobank.org/urn:lsid:zoobank.org:pub:971811AE-DF72-47E9-AED9-DEE835D1D412