Which genus contained the gastric-brooding frogs?

The gastric-brooding frogs belonged to the genus Rheobatrachus.

Rheobatrachus was an extinct genus of Australian frogs native to rainforest creek systems in Queensland. Its two known species were famous because the female swallowed fertilized eggs and brooded the developing young in her stomach. When development was complete, she expelled fully formed froglets through her mouth.

The embryos and tadpoles suppressed the mother’s stomach digestion, allowing the stomach to function temporarily as a brood chamber. This extraordinary reproductive method is the source of the name “gastric-brooding frog”; “platypus frog” was another common name.

Both species disappeared in the 1980s. The southern gastric-brooding frog was last seen in 1983, while the northern species was last seen in 1987. Their family placement has been debated, but the genus name Rheobatrachus is the canonical answer, not Hyla, Alytes, or Xenopus.