Ophryacus smaragdinus is a pit viper species endemic to the mountains of eastern Mexico. No subspecies are currently recognized.
The specific name Ophyracus is derived from the Greek language word ophrys (á½ÂÃÂÃÂÃÂÃÂ), which means "brow" or "eyebrow", and the Latin word acus, which means "needle", an allusion to the characteristic horn-like scales over the eyes; smaragdinus (or "emerald-green" in English) is the Latinization of the Latin noun smaragdus, which itself derives from the earlier Greek noun ÃÂüìÃÂñóôÿÃÂ, meaning emerald, i.e., a sharp horned toad with an emerald-green colored body.
Adults grow to between in length. No rattle. Supraocular horn is not in immediate contact with the eye. On lateral surfaces of head, a distinctive white, cream, or pale yellow triangular marking is present. Head wide with a rounded blunt snout. There are 3âÂÂ5 canthals present between the nasals and the supraocular scales. There are 1âÂÂ4 keeled postrostral internasals. Loreal pit is divided. Ventrals 155âÂÂ166, 3âÂÂ5 postoculars, 3âÂÂ5 suboculars, subcaudals 39âÂÂ46, 7âÂÂ9 supralabials and dorsal scale rows are 21-21-17.
Body emerald or olive green, which gives the common name. Sometimes it can be brown or tan. On dorsal surface, there are 37âÂÂ46 dark blotches, which are outlined in black. In mid dorsal region, these dorsal blotches are broken to form an undulating dark stripe. Juveniles are grey in color. Tail which is 12 to 15 in the total body length, contains 5âÂÂ12 pale bands. Head contains black spots and markings. A dark black-outlined postocular stripe is present.
It is found in east-central Hidalgo, west-central Veracruz, northeastern Puebla, and north-central Oaxaca. Habitats include montane cloud forest, humid pine-oak woodland and pine forest with secondary vegetation.
Terrestrial and less arboreal.