On Cytheridella whitmani sp. nov. (Crustacea, Ostracoda) from Cape Cod (Massachusetts, USA), with a reappraisal of the taxonomy of the genus

<i>Cytheridellawhitmani</i> Martens, <b>sp. nov.</b> is described from lakes on Cape Cod (MA, USA). The species differs from its congeners mainly by the shape of the female carapace and by the morphology of the hemipenis, especially of the distal lobe and the copulatory process. The literature on the genus is reviewed and the synonymy of the fossil <i>Cytheridellaboldii</i> Purper, 1974 with the type species <i>C.ilosvayi</i> Daday, 1905, both described from South America, is confirmed. The status of <i>Cytheridellaamericana</i> (Furtos, 1936) is reverted to that of "uncertain species". Beside the type species and the new species, the genus currently includes only three further species from Africa: <i>C.monodi</i> Klie, 1936, <i>C.damasi</i> Klie, 1944 (with synonym <i>C.chariessa</i> Rome, 1977), and <i>C.tepida</i> Victor, 1987. The morphology of the new species is discussed in comparison with the congeneric species, especially regarding the valve ornamentation, the structure and function of the third thoracopod, the hemipenis and the caudal ramus. It is suggested that <i>C.whitmani</i> is a recent invasive species in the lakes of the Cape Cod peninsula. Its occurrence at northern latitudes is unexpected, as its congeneric species are consistently (sub-) tropical.