Deamia testudo is a species of flowering plant in the family Cactaceae, native from southern Mexico through Central America to Nicaragua.

The flowers have a long thin base and widely spread white tepals.

[2] In 1965, Franz Buxbaum transferred it to the genus Selenicereus, based on its flowers, a view supported by Wilhelm Barthlott and David Hunt in 1993.

[7] Molecular phylogenetic studies in 2017 and in 2018 confirmed the monophyly of the genus Deamia,[7][8] of which D. testudo is the type species.

Deamia testudo is native from southern Mexico (southeastern, southwestern and Veracruz on the Gulf), through Guatemala, Belize and Honduras to Nicaragua.