Nyctimystes is a genus of tree frogs in the subfamily Pelodryadinae of the family Hylidae. They are principally Papuan species, but also inhabit islands in the Moluccas. All species in this genus have one distinct feature that separates them from other species in the family, the lower eyelid is marked with pattern of lines, veins, or dots. This feature presumably acts as camouflage when the frogs are at rest during the day.

Species of this genus inhabit tropical or subtropical montane rainforest. The eggs are large and are laid on submerged objects in fast-flowing creeks and streams (not all species of this genus have been recorded as doing this, although it is assumed). The tadpoles have large sucker-mouths and their body shapes are very streamlined with large tail musculatures. All species of this genus have extensive webbing and large toe discs.

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