Geoemyda

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.

Abstract: AB STRACT.– Phylo gen etic anal y sis of mi to chon drial gene se quence vari a tion in geoemydid tur tles sug gests that the ge nus Geoemyda as cur rently rec og nized is polyphyletic, and that Geoemyda yuwonoi is the sis ter taxon to Notochelys platynota (but the two are highly ge net i cally di ver gent). We herein place Geoemyda yuwonoi in a new monotypic ge nus, Leucocephalon, dis tin guished by its maxillary con tact, its lack of a quadratojugal, its large an te rior plastral but tresses, its humeropectoral seam pos te rior to the entoplastron, its long interanal seam, its pri mar ily pos te ri orly di rected neurals (dis tinctly con fig ured), and its lack of a plastral hinge.

Abstract: For a long time, turtles of the family Geoemydidae have been considered exceptional because representatives of this family were thought to possess a wide variety of sex determination systems. In the present study, we cytogenetically studied Geoemyda spengleri and G. japonica and re-examined the putative presence of sex chromosomes in Pangshura smithii. Karyotypes were examined by assessing the occurrence of constitutive heterochromatin, by comparative genome hybridization and in situ hybridization with repetitive motifs, which are often accumulated on differentiated sex chromosomes in reptiles. We found similar karyotypes, similar distributions of constitutive heterochromatin and a similar topology of tested repetitive motifs for all three species. We did not detect differentiated sex chromosomes in any of the species. For P. smithii, a ZZ/ZW sex determination system, with differentiated sex chromosomes, was described more than 40 years ago, but this finding has never been re-examined and was cited in all reviews of sex determination in reptiles. Here, we show that the identification of sex chromosomes in the original report was based on the erroneous pairing of chromosomes in the karyogram, causing over decades an error cascade regarding the inferences derived from the putative existence of female heterogamety in geoemydid turtles.

Abstract: The present study examined karyotypes of 16 genera and, along with previous reports, chromosomal data are now available for 18 of the 23 recognized batagurine genera. There are no karyotypic data available for the members of McDowell's (1964) Hardella complex. The Batagur, Heosemys and Geoemyda complexes retain the hypothesized primitive karyotype for the subfamily (2n=52). All the genera in these three complexes have been examined except Batagur and Annamemys. The Orlitia complex is karyotypically distinct with 2n=50 and the NOR located terminally on a large microchromosome. The genus Malayemys inclusion in the Batagur complex is not supported. Malayemys is characterized by a 2n=50 karyotype, with the NOR located interstitially on a large microchromosome. The Malayemys complex is erected to contain this genus at a point intermediate between the Orlitia complex and the subfamily Emydinae. Malayemys and the emydines are karyotypically indistinguishable. The Neotropical genus Rhinoclemmys (Geoemyda complex) differs only slightly from the primitive batagurine karyotype in the position of the NOR. The species R. funerea and R. punctularia further differ in possessing one less metacentric macrochomosome. An interesting situation involves two subspecies of R. punctularia. The nominate subspecies is characterized by a 2n=56 karyotype, while R. p. melanosterna reportedly has a 2n=52 karyotype. Such a difference is interpreted as indicative of genetic differentiation between the two forms of a magnitude inconsistent with considering them as conspecific. Taken together with zoogeographic considerations, the karyotypic difference between the forms R. p. punctularia and R. p. melanosterna seem sufficient to warrant species distinction for R. melanosterna as previously suggested by Pritchard (1979b).