Daniel Koleska et al. 364 to be absent in the Iguanidae, there are several recent records of supernumerary tail malformations of lizards belonging to this family; eg, Cophosaurus texanus (Mata-Silva et al., 2010), Cyclura carinata, C. cychlura, C. rileyi (Hayes et al., 2012) or Urosaurus bicarinatus (Mata-Silva et al., 2013). Etheridge (1967) noted that juveniles of Iguana iguana have skeletal adaptations allowing tail autotomy, which disappear as they grow older and reach maturity. Therefore we presume that our specimen suffered a tail injury during an early stage of its life and the tail bifurcation developed as a result. Tail breaks in Iguanidae are considered as outcomes of intraspecific aggression (Pérez-Buitrago et al., 2010), sexual aggression during mating (Iverson et al., 2004) or failed attempts of predation (Hayes et al., 2012). Nevertheless, as far as we know, this is the first record of tail bifurcation for this species and one of the few recorded in the Iguanidae. Tail regeneration is of recent interest as a comparative model for regenerative medicine (Alibardi, 2010; Delorme et al., 2012). Therefore we believe that our observation on this anatomical anomaly could have certain value for future research.

Acknowledgements. We thank Jiří Marek from Zoopark Zájezd (Czech Republic) for providing access to the specimen. This work was supported by the Internal Grant Agency of the Czech University of Life Sciences Prague (CIGA) through Project No. 20172002.