Lacunolabial scale explained

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.^{[1] [2]} In such cases, it is often said that "the second labial enters the pit".^[3] Some pitvipers, such as Bothrops alternatus, Bothrops erythromelas, Bothrops itapetiningae and Bothrops neuwiedi, have a divided lacunolabial scale.^[4]

Notes and References

1. Book: Wareham . David C. . Elsevier's dictionary of herpetological and related terminology . 2005 . Elsevier . Amsterdam . 9780080460178 . 114 . 1st.
2. Book: Campbell . Jonathan A. . Amphibians and reptiles of northern Guatemala, the Yucatán, and Belize . 1998 . University Of Oklahoma Press . Norman . 9780806130668 . 339.
3. Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. 2 volumes. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. .
4. Machado . Taís . Silva . Vinícius X. . Silva . Maria José de J. . Phylogenetic relationships within Bothrops neuwiedi group (Serpentes, Squamata): Geographically highly-structured lineages, evidence of introgressive hybridization and Neogene/Quaternary diversification . Molecular Phylogenetics and Evolution . 1 February 2014 . 71 . 1–14 . 10.1016/j.ympev.2013.10.003 . 2014MolPE..71....1M . 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.. free .