The origin of the Malesian fossil turtle diversity: Fossil versus molecular data

Abstract

The origin of the turtle fauna of Malesia is analysed here through a review of the literature, a re-evaluation of previously described material, and the description of new material. Very few data are available prior to the Quaternary. While the Early Pleistocene record is largely dominated by reports of giant tortoises, the Middle Pleistocene record provides reports of the first occurrences of most extant taxa living in the area. Most, if not all, of the faunas have stronger relationships with Indochinese than with East Asian taxa, suggesting that colonisation largely followed the Siva- or Sino-Malayan routes, allowing turtles to invade the Sunda Shelf and disperse further east during periods of low sea-level. On the other hand, there is nearly no fossil data to understand the origin of the six endemic Malesian species, but molecular studies suggest that most of these taxa may have evolved in Malesia well before the Quaternary dispersal of the Indochinese fauna. In addition to clarify several fossil identifications, we provide evidence that the box turtle of the ``Cuora amboinensis'' species complex arrived in the Philippines before the early Middle Pleistocene. We also confirm that Duboisemys isoclina is an endemic extinct genus and we discuss its relationship to continental and endemic turtles.