[2] The underworld windowskate is known from patches of continental slope in the western Atlantic Ocean between the coasts of the southern United States and Suriname.

[7] The underworld windowskate has a heart-shaped disc, with denticles on the blunt snout, around the eyes, on the pectoral fins and down the sides of the long tail.

[1] Finally, two widely separated groups occupy the southern Caribbean Sea, the first off Costa Rica, near Puerto Limon, and the second from the South American continental shelf near Caracas, Venezuela, to Paramaribo, Suriname.

[1] Outside of these general ranges, specimens have been collected from the waters off Colombia, Ellesmere Island, in the eastern Gulf of Mexico, and James Bay, Canada.

[9] Individuals have also been spotted by divers in southern Mexico, and in 1891 a specimen supposedly belonging to F. plutonia was collected from the California coast, even though the underworld windowskate is overwhelmingly an Atlantic species.