Nyctimystes is a genus of tree frogs in the family Pelodryadidae. Most of them are from Papua New Guinea but some live on the Moluccas islands.  Some scientists think Nyctimystes should be considered part of Litoria, another genus of frogs from New Guinea.  Other scientists think that it is right to say Nyctimystes is its own genus.

All frogs in Nyctimystes have marks on their lower eyelids: lines, veins, or dots. Scientists think this helps the frog harder to see so it can hide from larger animals that want to eat it.  Scientists tell Nyctimystes frogs apart from Litoria frogs because Nyctimystes frogs have vertical (up and down) pupils in their eyes and Litoria frogs have horizontal (side to side) pupils in their eyes.

These frogs live in tropical or subtropical rainforests on mountains. Their eggs are large and scientists have seen many of them laying eggs on underwater objects in fast-flowing creeks and streams, enough that they think all Nyctimystes frogs do this. The tadpoles have large sucker-mouths and streamlined bodies with large, muscular tails. All Nyctimystes frogs have webbed feet and large discs on their toes for climbing.

Scientists say most Nyctimystes frogs became separate species during the Miocene era, about 10 to 22 million years ago.

The name comes from the Greek nycktos for "night" and myst meaning "mist." Together they refer to "mysteries of the night."

Species
Many of these frogs are few in number in the wild, and scientists do not know much about most of them. Scientists often write papers saying a frog species should be renamed and moved from Nyctimystes into Litoria or Ranoidea, so the list below may change:

 Nyctimystes avocalis (Zweifel, 1958) - Loud big-eyed tree frog
 Nyctimystes bivocalis (Kraus, 2012)
 Nyctimystes brevipalmatus (Tyler, Martin, and Watson, 1972) - Green-thighed frog
 Nyctimystes calcaratus (Menzies, 2014)
 Nyctimystes cheesmani (Tyler, 1964) - Cheesman's big-eyed tree frog
 Nyctimystes cryptochrysos (Kraus, 2012)
 Nyctimystes daymani (Zweifel, 1958) - Dayman big-eyed tree frog
 Nyctimystes disruptus (Tyler, 1963) - Madang big-eyed tree frog
 Nyctimystes dux (Richards and Oliver, 2006)
 Nyctimystes eucavatus (Menzies, 2014)
 Nyctimystes fluviatilis (Zweifel, 1958) - Indonesian big-eyed tree frog
 Nyctimystes foricula (Tyler, 1963) - Kaironk big-eyed tree frog
 Nyctimystes granti (Boulenger, 1914) - Grant's big-eyed tree frog
 Nyctimystes gularis (Parker, 1936) - Mondo big-eyed tree frog
 Nyctimystes humeralis (Boulenger, 1912) - Green big-eyed tree frog
 Nyctimystes intercastellus (Kraus, 2012)
 Nyctimystes kubori (Zweifel, 1958) - Sandy big-eyed tree frog
 Nyctimystes kuduki (Richards, 2007)
 Nyctimystes latratus (Menzies, 2014)
 Nyctimystes montanus (Peters et Doria, 1878) - Mountain big-eyed tree frog
 Nyctimystes myolae (Menzies, 2014)
 Nyctimystes narinosus (Zweifel, 1958) - Common big-eyed tree frog
 Nyctimystes obsoletus (Lönnberg, 1900) - Simbang big-eyed tree frog
 Nyctimystes ocreptus (Menzies, 2014)
 Nyctimystes pallidofemora (Kraus, 2018)
 Nyctimystes papua (Boulenger, 1897) - Papua big-eyed tree frog
 Nyctimystes perimetri Zweifel, 1958 - Archipelago big-eyed tree frog
 Nyctimystes persimilis (Zweifel, 1958) - Milne big-eyed tree frog
 Nyctimystes pulcher (Wandolleck, 1911) - Spurred big-eyed tree frog
 Nyctimystes rueppelli (Boettger, 1896) Rueppel's big-eyed tree frog
 Nyctimystes sanguinolenta (Van Kampen, 1909) - Sabang tree frog
 Nyctimystes sauroni (Richards and Oliver, 2006)
 Nyctimystes semipalmatus (Parker, 1936) - Kokoda big-eyed tree frog
 Nyctimystes trachydermis (Zweifel, 1983) - Morobe big-eyed tree frog
 Nyctimystes traunae (Menzies, 2014)
 Nyctimystes tyleri (Zweifel, 1983) - Tyler's big-eyed tree frog

References

The IUCN Redlist - Nyctimystes
 Barker, J.; Grigg, G.C.; Tyler, M.J. (1995). A Field Guide to Australian Frogs. Surrey Beatty & Sons.

Frogs