Abstract
Monophyly of the batagurid subfamily Geoemydinae was evaluated, and phylogenetic relationships within the subfamily were inferred on the basis of 35 morphological characters. Two approaches, parsimony analysis using the branch and bound algorithm, and neighbor joining clustering of an absolute distance matrix, were used. The results of these analyses yielded phylograms that were almost identical in branching topology, and poorly supported the monophyly of Geoemydinae. This subfamily thus seems to be a metataxon, most likely consisting of the sister group of Batagurinae (Geoemyda group) and a more primitive stock of Bataguridae (Mauremys group). The latter accommodates Mauremys and Sacalia and its monophyly is not well supported. The former consists of the remaining ten geoemydine genera united by two synapomorphies-absence or reduction of the quadratojugal, and posteriorly short-sided anterior neurals. Relationships revealed by our analyses necessitate some changes in the generic classification of Geoemydinae. First of all, Cistoclemmys Gray, 1863 (type species: Ci. flavomarginata, often synonymized to Cuora Gray, 1855 (type species: Cu. amboinensis), is shown to be a valid genus closely related to Pyxidea and Geoemyda rather than to Cuora (sensu stricto). Rhinoclemmys Fitzinger, 1835 (type species: R. punctularia) is shown to be polyphyletic, and Chelopus Cope, 1870 (type species: C. rubida), is resurrected to accommodate R. rubida and R. annulata. The plastral hinge seems to have evolved three times in the Bataguridae-in the Cyclemys-Notochelys clade, Cuora (sensu stricto), and the Cistoclemmys-Pyxidea clade.
