The nomenclatural status of Zaocys carinatus Günther, 1864 (Squamata, Serpentes)

The nomen ‘Ptyas carinata (Gunther, 1858)’, applied since 1864 to a large colubrid snake species of the Oriental region first reported from Borneo, is shown to be in fact an invalid junior objective synonym of Ptyas dhumnades (Cantor, 1842), a species of the same genus inhabiting China, Laos and Vietnam. In order to preserve the use of the well-known combination Ptyas carinata for the former species, Article 23.9 on reversal of precedence is used to validate Zaocys carinata Gunther, 1864 against its senior secondary homonym Coryphodon carinatus Gunther, 1858.