Cratera assu is a species of land planarian belonging to the subfamily Geoplaninae.

[1] It is known from specimens found in Serra da Bocaina National Park in Brazil.

The dorsal side of the body can vary in color from chestnut brown to black-brown.

The ventral side of the body can range from sand yellow to light ivory in color.

[2] Aside from its coloration and length, it is distinguished from other members of Cratera by having dorsal eyes, a bell-shaped pharynx, a horizontal penis papilla, a widened distal portion of the ejaculatory duct that occupies most of the penis papilla, and the lack of a common glandular ovovitelline duct.