Euryale tenuicostata is a fossil species of Euryale from the Miocene of Omsk, Russia.
The ovoid to oval, 4.3âÂÂ7.6 mm long, and 2.9âÂÂ7.1 mm wide seeds have a slightly wrinkled testa.
It was first published as Euryale tenuicostata by Pavel Ivanovich Dorofeev in 1959. It has been proposed to place it in a separate genus Irtyshenia as Irtyshenia tenuicostata published by Pavel Ivanovich Dorofeev in 1972. Later it was proposed to place it in the genus Pseudoeuryale as Pseudoeuryale tenuicostata published by Alexander Borisovitch Doweld in 2022.
Fossils of E. tenuicostata occur in what is now Russia.