Vipera ursinii renardi
Adults average 40–50 cm (16–20 inches) in total length, although specimens of 63–80 cm (25–31½ inches) have been reported. Females are larger than males. Although sometimes confused with V. aspis or V. berus, it differs from them in the following characters. The smallest viper in Europe, its body is thick, its head narrow, and its appearance rough. The snout is not upturned. There are always several large scales or plates on the top of the head. The prominently keeled dorsal scales are in only 19 rows, and often dark skin shows between them. It is gray, tan, or yellowish with a dark undulating dorsal stripe, which is edged with black. (information from Wikipedia)
This spotting took place at Oklahoma City Zoo.