Black-speckled Palm Pit Viper

Adults may exceed 80 centimetres (31 in), although most are less than 60 centimetres (24 in) in length. They are relatively slender and have a prehensile tail. Two exceptionally large females were reported by Hammack and Antonio (1991) that measured 89.2 centimetres (35.1 in) and 93.7 centimetres (36.9 in).

The color pattern usually consists of an emerald green (rarely yellowish green) ground color with strong black mottling. There may also be pale green dorsal blotches that have black edges. The belly is yellowish green and lightly mottled with black. The head is heavily mottled with black on top, often with black parietal stripes. There is also a clearly defined postocular stripe running back towards the angle of the jaw. The iris is heavily stippled and appears almost black. The tongue is also black. Juveniles have a similar color pattern, although it is more pale and the tip of the tail is black.

Found in the mountains of Costa Rica and Panama. Also found in the cloud forests of the Cordillera Central and the Cordillera de Talamanca at 1,150–2,400 m altitude. The type locality given is "Vulcan von Barbo" (Volcán Barba, Costa Rica). According to Campbell and Lamar (2004), this species prefers medium to high elevations from 1,150 to over 3,000 m, and is found from the Cordillera Tilarán and Cordillera Central in the southeastern Alajuela province in Costa Rica, southeast through the Cordillera de Talamanca to Chiriquí province in Panama. It occurs on both the Atlantic and Pacific slopes.