The Lower Mekong: an insurmountable barrier to amphibians in southern Indochina?

Abstract

Geographical information system (GIS)‐based cluster analyses and comparative ecological approaches were applied to unravel the hitherto controversially discussed role of the Mekong River as a biogeographical barrier to the amphibian fauna in Indochina. Referring to the unique and independent history of the Lower Mekong, south of the Lao–Cambodian border, this approach focused on the amphibians of southern Indochina and adjacent parts of eastern Thailand. To date, 131 amphibian species have been recorded from this region. In concordance with previous studies, our GIS‐based analyses revealed that the amphibian fauna of the Cardamom Mountains, west of the Mekong, possessed no closer affinity to the herpetofauna of the Southern Annamites. In addition, a statistical comparison of ecological characters showed an occurrence of ecological differentiation among amphibians across the Lower Mekong. Our results suggest that the Lower Mekong serves as, or at least coincides with, a biogeographical barrier in southern Indochina. Here, we discuss this hypothesis, together with selected species spatial distribution patterns, their species‐specific ecological traits and the palaeogeographical background of the region. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 905–914.

A new species of Oligodon Fitzinger, 1826 from the Langbian Plateau, southern Vietnam, with additional information on Oligodon annamensis Leviton, 1953 (Squamata: Colubridae)

“…Hence, O. annamensis has a disrupted range confined to Langbian Plateau in the east and to Cardamom Mountains in the west and separated by the Mekong River valley. Interestingly, a similar distribution pattern was recently reported for a number of lizard taxa inhabiting Indochina (e.g., Grismer et al, 2019;Poyarkov et al, 2019a), but was never recorded in Indochinese amphibians (Geissler et al, 2015b).…”

“…1, locality 1). This montane area is characterized by high levels of local endemism (Nazarov et al, 2012;Poyarkov et al, 2014;Poyarkov et al, 2015a;Poyarkov et al, 2015b;Poyarkov et al, 2017;Poyarkov et al, 2019b;Stuart et al, 2011;Rowley et al, 2016); further research is needed to clarify the distribution of the new species.…”

“…Located in middle of the Southeast Asian biodiversity hotspot, the Langbian Plateau is known as a local center for herpetofaunal endemism. It is inhabited by numerous species of amphibians and reptiles, many of which were only described recently Nazarov et al, 2012;Poyarkov et al, 2014;Poyarkov et al, 2015a;Poyarkov et al, 2015b;Poyarkov et al, 2017;Poyarkov et al, 2019b;Stuart et al, 2011;Rowley et al, 2016;Vassilieva et al, 2014). The Kukri Snakes of the genus Oligodon Fitzinger, 1826, are one of the most speciose and taxonomically problematic colubrid snake groups distributed in South and Southeast Asia, with over 79 species described (Green, Orlov & Murphy, 2010;Wallach, Williams & Boundy, 2014;Uetz, Freed & Hošek, 2019).…”

Population genetic structure of the endemic rosewoods Dalbergia cochinchinensis and D. oliveri at a regional scale reflects the Indochinese landscape and life‐history traits

“…The lower Mekong and the Mekong Delta have been recognized as a biogeographical barrier to distribution of mammal and amphibian species with a high diversity of endemics found east of the Mekong (Geissler et al., ; Meijaard & Groves, ). The present course of the Mekong River is only around 5000 years old (Woodruff, ); however, the proximate location of the Lower Mekong has been separating the Annamite Mountains from the Cardamom Mountains since late Miocene (Geissler et al., ; Hutchison, ).…”

Molecular, morphological and acoustic assessment of the genus Ophryophryne (Anura, Megophryidae) from Langbian Plateau, southern Vietnam, with description of a new species

“…The Langbian Plateau is known for its high herpetofaunal diversity and endemism, a significant portion of which has been discovered only recently (e.g., Orlov et al 2008, 2012, Rowley et al 2010c, 2011a, 2011b, 2016, Stuart et al 2011, Poyarkov [Paiarkov] and Vassilieva 2011, Nazarov et al 2012, Chan et al 2013, Hartmann et al 2013, Geissler et al 2014, 2015, Vassilieva et al 2014, Poyarkov et al 2014, 2015a, 2015b). Despite this increase in species discoveries, many areas of the Annamites have received little scientific attention and are very likely to host further previously unknown diversity.…”