This species occurs in countries including: The type locality is Santa Cruz near Mt.

of Observation on the Rio Chico 50 miles above Sierra Oveja, on a dry stone near the water (according to F. von Ihering).

[4] The shell is openly umbilicate (the umbilicus about one-fourth the total diameter), of a uniform pale brown tint, discoidal.

[4] The original description, in Portuguese, was based upon fossil specimens, which had lost the color and part of the finer sculpture.

The original lot of Radiodiscus patagonicus was from Santa Cruz, on the coast, in a modern deposit.