Voici le point de vue de Van Wallach (comm pers. à Ivan INEICH le 22 juin 2016 ) par rapport à sa position adoptée en 2014 :

We followed Zaher (1999: 40, 76) in our snake catalogue in not recognizing Thalesius viridis, which was based solely on the attenuate arms of the hemipenis, because of Zaher's extensive knowledge of hemipenial variation.  Then later on, Myers & McDowell (2014: 78) further agreed with Zaher's conclusions.  Zaher's Fig. 82 (X. rabdocephalus) and Myers' Figs. 18–19 (X. rabdocephalus) clearly show the resemblance to that of T. viridis  (Yuki, figs. 3–4) so I think there is no doubt that the proper name for the species is X. werneri. Xenodon rabdocephalus, X. werneri, and "Thalesius viridis" all share two synapomorphies: they lack the apical disks of other Xenodontini (considered a derived condition) and they have an expanded cervicomandibularis muscle insertion site through the dorsal side of the quadratomaxillaris ligament anterior to the quadratomandibular capsule (a synapomorphy of the Xenodontini as described by Serra, 1949, and Romano & Hoge, 1972).  Additionally, the bifurcated arms of the hemipenis are quite slender in these species, in contrast to other Xenodon.Therefore, Thalesius must be a synonym of X. werneri as most authors have stated.