They are closely related to the giant salamanders (family Cryptobranchidae), with which they form the suborder Cryptobranchoidea.

About half of hynobiids currently described are endemic to Japan, but their range also covers parts of China, Russia, Afghanistan and Iran.

And, unlike other salamander families which reproduce internally, male hynobiids focus on egg sacs rather than females during breeding.

Larvae can sometimes have reduced external gills if they live in cold and very oxygen-rich water.

[6] Cladograms based on the work of Pyron and Wiens (2011)[7] and modified using Mikko Haaramo [8] ?†Iridotriton hechti ?†Liaoxitriton ?Protohynobius puxiongensis Onychodactylus Pachyhynobius shangchengensis Salamandrella Hynobius Ranodon sibiricus Paradactylodon Batrachuperus Liua Pseudohynobius Currently, 81 species are known.