H. platirhinos can reach a maximum length of 1 m, averaging between 50 to 84 cm. All species of this genus can be recognized by the characteristic upturned and pointed snout. The dorsal coloring in H. platirhinos varies greatly, it can be khaki-green, yellowish-brown, or reddish-brown, all patterned with various combinations of darker spots and splotches. Some individuals are entirely black, but most are yellowish with dark brown blotches (Tennant, 2003). Regardless of age or color, there is always a dark blotch behind the jaw. This blotch extends posteriorly along the sides of the neck. The ventral scales are typically gray (occasionally with orange blotches), and the underside of the tail is usually lighter than the rest of the belly (Tennant, 2003).
The body is H. platirhinos is stocky, with a short head that is not distinct from the wide neck (Tennant, 2003).