Evolutionary Relationships Of Recent Trionychid Turtles PDF Download

Phylogenetic analysis of nearly one hundred characters of the osteology of trionychid turtles provides abundant data on the phyletic relationships of this family to other turtles and on the interrelationships of its members. These data suggest that the family Trionychidae shares a unique common ancestor with the Dermatemydidae, Kinosternidae and Carettochelyidae , and that the Kinosternidae shares a unique common ancestor with the Trionychidae and Carettochelyidae. Furthermore, it is the staurotypine kinosternids that are most closely related to the Trionychidae and Carettochelyidae. Carettochelyids and trionychids share numerous unique features and constitute a monophyletic group . Within the Trionychidae, the subfamilies Cyclanorbinae and Trionychinae are recognized as monophyletic clades. Recognition of three cyclanorbine genera, Cycloderma , Cyclanorbis and Lissemys , is warranted. Within the Trionychinae, four distinct clades are recognized. The Trionyx cartilaglneus group includes Chitra indica and Pelochelys bibroni on the basis of the unique location of the foramen posterior canalis carotici interni, and features of the trigeminal region. The North American group, which includes T. triunguis , T. euphraticus , T. swinhoei , T. ferox , T. spiniferus and T. muticus, can be recognized by the presence of eight or fewer neurals (first and second are fused), deeply emarginate prefrontals and a large contribution by the parietal to the processus trochlearis oticum. The Indian group includes four species: T. gangeticus , T. hurum , T. leithii and T. nigricans . All exhibit a free first neural, five plastral callosities and intermediately extended epiplastra. Lastly, the T. steindachneri group is diagnosed by a descending spine of the opisthotic which divides the fenestra postotica in most specimens. Two equally parsimonious arrangements of the Trionychinae differ in the placement of the North American clade. In one, this clade is the sister group of the T. cartilagineus clade; in the other it is the sister group of the T. steindachneri clade. In both, the Indian group is paraphyletic and gives rise to the T. steindachneri clade. A tentative revision of the classification of the family Trionychidae is provided. In it, five generic names currently in the synonymy of Trionyx are resurrected to denote unique clades of trionychine turtles.