The lacunolabial scale is a large scale that forms in some crotaline snakes (pitvipers) when the prelacunal scale fuses with the second (rarely the third) supralabial scale. In such cases, it is often said that "the second labial enters the pit". Some pitvipers, such as Bothrops alternatus, Bothrops erythromelas, Bothrops itapetiningae and Bothrops neuwiedi, have a divided lacunolabial scale.
References
- Wareham, David C. (2005). Elsevier's dictionary of herpetological and related terminology (1st ed.). Amsterdam: Elsevier. p. 114. ISBN 9780080460178.
- Campbell, Jonathan A. (1998). Amphibians and reptiles of northern Guatemala, the Yucatán, and Belize. Norman: University Of Oklahoma Press. p. 339. ISBN 9780806130668.
- Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. 2 volumes. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.
- Machado, Taís; Silva, Vinícius X.; Silva, Maria José de J. (1 February 2014). "Phylogenetic relationships within Bothrops neuwiedi group (Serpentes, Squamata): Geographically highly-structured lineages, evidence of introgressive hybridization and Neogene/Quaternary diversification". Molecular Phylogenetics and Evolution. 71: 1–14. Bibcode:2014MolPE..71....1M. doi:10.1016/j.ympev.2013.10.003.
Burger (1971) first proposed the B. neuwiedi group based on morphological traits grouping B. neuwiedi with B. itapetiningae and B. iglesiasi. Werman (1992), based on morphology and protein electrophoresis, expanded the B. neuwiedi group to include a wider assemblage composed of the species with a divided lacunolabial scale, i.e. B. alternatus, B. erythromelas, B. itapetiningae and B. neuwiedi.