A revision of the species group of Xenochrophis piscator (Schneider, 1799)(Squamata: Natricidae)

摘要

Morphological variation was investigated across the entire geographic range of the snakes of the Xenochrophis piscator species group. Our results, based on morphological univariate analyses, show the existence of several well-defined clusters identified as species. Xenochrophis flavipunctatus (Hallowell, 1861) is distinct from X. piscator (Schneider, 1799) and sympatric with it over a large area. Xenochrophis tytleri (Blyth, 1863) is confirmed as the valid combination for the population living on theAndaman Islands. Xenochrophis asperrimus (Boulenger, 1891) is confirmed, with species status, for populations from Sri Lanka. Xenochrophis melanzostus (Gravenhorst, 1807) is accepted, as a distinct species most probably endemic to Java. Xenochrophis schnurrenbergeri Kramer, 1977 is confirmed for populations from Nepal, southeastern Pakistan, and northern and eastern India. Tropidonotus sanctijohannis Boulenger, 1891 seems to be a montane colour morph of X. piscator and is not regarded here as valid. The second population of "X piscator^ on Sri Lanka is regarded as different from that of the mainland, but it is not named here due to the uncertain relationships among populations of southern India and Sri Lanka. The variation of X. piscator sensu strictois discussed. All taxa are redescribed on the basis of new material. The history of all synonyms is discussed and neotypes are designated for Hydrus palustris Schneider, 1799, Coluber melanzostus Gravenhorst, 1807 and Amphiesma jlavipunctatum Hallowell,1861. The holotype of Hydrus piscator Schneider 1799 has been rediscovered and is discussed.