Salmon: a new autosomal mutation demonstrating incomplete dominance in the boine snake Boa constrictor.

An unusual and attractive pigmentation pattern mutation termed "salmon" has been identified in the United States in several captive colonies of the common neotropical boine snake boa constrictor [Boa constrictor (Boidae)]. Boa constrictors expressing the Sa pigmentation pattern appear to be restricted to regions of Panama. Animals with the Sa phenotype exhibit a sharp decrease in melanophore pigments (e.g., melanin) and an increase of xanthophore pigments (e.g., pteridines and carotenoids) throughout the body, including ventral and caudal regions. Moreover, the dorsal saddles (blotches) and lateral diamond patterns are greatly reduced and/or absent. Our study was initiated using a female B. constrictor born in captivity and expressed the Sa pigmentation pattern. Results from breeding experiments indicated an inheritance mode of autosomal incomplete dominance for the Sa and Wt alleles.