Rhinoclemmys, AND

Le, Minh & Mccord, William P., 2008, Phylogenetic relationships and biogeographical history of the genus Rhinoclemmys Fitzinger, 1835 and the monophyly of the turtle family Geoemydidae (Testudines: Testudinoidea), Zoological Journal of the Linnean Society 153 (4), pp. 751-767 : 763

RELATIONSHIP BETWEEN RHINOCLEMMYS AND

OTHER GENERA AND THE MONOPHYLY OF THE FAMILY GEOEMYDIDAE

The results from the present study strongly support the monophyly of the family Geoemydidae (BP = 85% in MP, BP = 71% in ML; PP = 98%) inclusive of Rhinoclemmys . This is the first broad-sampling molecular analysis that strongly supports the monophyly of the family with regard to testudinids, and also supports the subfamilial status of Rhinoclemmys . We herein propose to raise this genus to subfamily rank with the name of Rhinoclemminae. Morphologically, all species of the genus share at least two synapomorphies, the absence of lateral keels throughout their life ( Claude & Tong, 2004) and the shape of the upper triturating surface (our pers. observ.). Examination of 60 specimens of all species in this genus and 63 specimens of other species (see supplementary Appendix S2) belonging to other major clades of the family reveals that the upper triturating surface in this group is different from that of other geoemydid species in that it is narrower in the anterior portion and expanded in the posterior potion. In addition, the upper triturating surface has a minimal lingual ridge on the inner rim. Carr (1991) proposed other synapomorphies for this group, but these characters either vary among other geoemydids or could not be checked because they are either karyotypic or biochemical characters.

Although the other major clade of geoemydids, exclusive of Rhinoclemmys , is not strongly supported by the MP analysis, it is consistently recovered in all of our analyses and received strong support from the Bayesian and ML analyses. Biogeographically, it is a distinct clade containing mostly Asian taxa. Within this clade, our MP results show the same topology as the one recovered by Diesmos et al. (2005). However, several basal nodes have significantly higher BP values, such as the clade consisting of Cuora + Mauremys + Cyclemys + Heosemys + Sacalia (BP = 90% vs. 57%) and the clade of Cyclemys + Heosemys + Sacalia (BP = 97% vs. 74%). The topology resulting from our Bayesian and ML analyses for this major clade is the same as one proposed by Spinks et al. (2004), but the support values in all nodes are generally higher. The most significant discrepancy between our MP and the Bayesian and ML analyses is the position of Geoemyda . It is likely, however, that this problem could be eliminated by increasing taxon sampling. We are currently investigating this problem using more taxa and more molecular data.

In terms of the synapomorphy of this family, we agree with Hirayama (1984) and Yasukawa et al. (2001) that the presence of inguinal and axillary musk duct foramina is the character uniting all geoemydids. This hypothesis has been criticised as musk duct foramina are also present in other groups of turtles ( Waagen, 1972; Ehrenfeld & Ehrenfeld, 1973; Gaffney & Meylan, 1988; Weldon & Gaffney, 1998; Joyce & Bell, 2004). Nevertheless, the musk duct positions and formation can be used to differentiate geoemydids from emydids and testudinids. Within testudinoids, emydids tend to have only one pair of musk duct foramina in the axillary region and testudinids do not possess these foramina. Geoemydids commonly have two pairs, in the axillary and inguinal buttresses. The genus Morenia used to be considered the only geoemydid genus that does not possess musk duct foramina ( Waagen, 1972; Yasukawa et al., 2001; Joyce & Bell, 2004), but our observation of a Morenia ocellata specimen (see supplementary Appendix S2) revealed that they do have two pairs of small musk duct foramina as do other geoemydids. Yasukawa et al. (2001) also proposed that expanded iliac blades distinguish the family Geoemydidae from all other families, but we were unable to check this character due to the rarity of complete iliac blades in examined specimens.