The speciesHolophagus penicillata/penicillatus from the Late Jurassic of Europe is now assigned to the genus Undina. The species Holophagus picenus from the Middle Triassic of Europe has also been reassigned by some authors to Undina. At least some specimens assigned to the genus from the Upper Jurassic of Germany actually belong to the genus Libys. The species Holophagus leridae from the Early CretaceousEl Montesecsite in Spain, with other remains tenatively referred from the Early CretaceousLas Hoyaslocality also in Spain, probably do not belong in the genus, but have yet to be reassigned elsewhere.