New record for Colombia, updated distribution map, and comments on the defensive behavior of Thamnodyastes dixoni Bailey & Thomas, 2007 (Serpentes, Dipsadidae, Xenodontinae)

The original description of Thamnodynastes dixoni Bailey & Thomas, 2007 was based on few specimens, and the morphological variation, distributional range, and ecological aspects of this species are virtually unknown. The species is known to occur in the Llanos of Colombia and Venezuela. In Colombia, it was recorded only in four localities. We report a fifth occurrence of T. dixoni in Colombia and the first in the Department of Meta. The new record extends this species' distribution nearly 150 km (in a straight line) from the nearest previously known occurrence at Paz de Ariporo, Department of Casanare. Additionally, we also provide comments about the species' defensive behavior, not reported elsewhere, and a thorough revision on the species' geographical distribution.