Obama decidualis is a species of land planarian belonging to the subfamily Geoplaninae.

Obama decidualis has a foliaceous, or leaf-shaped, and elongate body that can reach up to 60 mm in length.

[2] The sensory pits are invaginations in a single row on each side of the body.

The ejaculatory duct is almost straight, and the penis papilla is irregularly shaped and projecting from the anterior male atrium.

[2] Obama decidualis is known to be found in and on the borders of temperate deciduous forests within the municipality of Santa Maria in Rio Grande do Sul, Brazil.