We redescribe the type material of Phyllodactylus siamensis Boulenger, 1899, type species of the Southeast Asian gekkonid genus Dixonius Bauer, Good & Branch, 1997, using external morphology and cranial osteology (by Micro-Computed Tomography, µ-CT). There is some evidence that the type series contains more than one species; we hence designate a lectotype in order to stabilize nomenclature and provide more precision on the geographical location of the type locality. Because the current concept of Dixonius siamensis auctorum is incomplete and composite, we provide a revised diagnosis based on the presently designated lectotype and a paralectotype from the same locality, as well as observations on new material from the type locality and the first photographs of live topotypical individuals. We regard Dixonius siamensis as probably geographically restricted to the Dong Phaya Yen mountain range in central Thailand, and the numerous published mentions of this species from outside this range likely refer to other or undescribed taxa. We treat Phyllodactylus burmanicus Annandale, 1905 from Tavoy, southern Myanmar, as a valid species, as Dixonius burmanicus comb. nov.
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We here provide a detailed description of the vertebral morphology of the African arboreal viperid snakes of the genus Atheris. Vertebrae of three different species of the genus, i.e., Atheris desaixi, Atheris hispida, and Atheris katangensis, were investigated via the aid of μCT (micro‐computed tomography) scanning. We describe several vertebrae from different regions of the vertebral column for all three species, starting from the atlas‐axis complex to the caudal tip, in order to demonstrate important differences regarding the intracolumnar variation. Comparison of these three species shows an overall similar general morphology of the trunk vertebrae among the Atheris species. We extensively compare Atheris with other known viperids. As the sole arboreal genus of Viperinae the prehensile nature of the tail of Atheris is reflected in its caudal vertebral morphology, which is characterized by a high number of caudal vertebrae but also robust and anteroventrally oriented pleurapophyses as a skeletal adaptation, linked with the myology of the tail, to an arboreal lifestyle. We anticipate that the extensive figuring of these viperid specimens will also aid identifications in paleontology.
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