Royal Tree Toad

Adult males measure 33–36 mm (1.3–1.4 in) in snout–vent length. There are two distinct color morphs of adult males: a greenish brown or greenish black dorsal coloration, both with scattered golden yellow blotches and white dots that form oblique lateral stripes; the blotches and dots are also present on the dorsal faces of the fore and hind limbs. The ventral faces of the arms, tibiae, and thighs, as well as the concealed dorsal surfaces of tarsi and feet, are vivid purple-red. Ventral surfaces are peppered with well-defined white spots. The belly is red. Males emit both advertisement calls and territorial calls. Calling takes place during the day. A Gosner stage 35 tadpole measured 52 mm (2.0 in) in total length and 19 mm (0.75 in) body length.

The known distribution of Hylodes regius is restricted to a single valley in the Itatiaia Mountains that is contained within the Itatiaia National Park. It occurs in primary forest in and around streams at elevations of 1,850–2,100 m (6,070–6,890 ft) above sea level. Males can be found calling between rocks, on the ground, and perched on shrubs.