Abstract: 27 morphological characters and 18S rDNA sequences of the 9 main ostracod groups were analyzed by the maximum parsimony method to construct a consensus phylogenetic tree. The results indicate that punciidaen ostracods form a separate clade which may be placed under the subclass ‘Punciocopa’, with the same status as Podocopa and Myodocopa, but more evidence is still needed to confirm it. The classification status of halocypridian ostracods was undetermined because the topology was different on two phylogenetic trees. Among the three subclasses suggested in the study, Podocopa includes the suborders Cypridocopina, Cytherocopina, Bairdiocopina, Darwinulocopina and the family Cytherellidae; Myodocopa consists of at least two orders, Cladocopida and Myodocopida; and Punciocopa has only one family, Punciidae. This provides new evidence for solving the unstable higher classification of living ostracods.

Key words: Ostracoda, 18S rDNA, morphological characters, classification