Phenotypic variations and melanism in an introduced population of the adder Vipera berus in eastern Belgium ; Variations phénotypiques et mélanisme au sein d'une population introduite de Vipère péliade Vipera berus dans l'est de la Belgique

International audience ; A great variation of phenotypes, including melanism, is observed within a population of adder introduced into a vast peatland site in eastern Belgium. This surprisingly large polymorphism is usually not encountered in this species in Belgium and France.