Type species. Aclis (supranitida Wood var. ?) lata Dall, 1889b, by original designation, Recent; Caribbean.
Diagnosis. See Bouchet & Warén (1986: 444). Remarks. Umbilibalcis Bouchet & Warén, 1986 comprises three species, all from the North Atlantic: Um-bilibalcis crassula Bouchet & Warén, 1986, U. lata (Dall, 1889b) and U. subumbilicata (Jeffreys, 1883) (Bouchet & Warén 1986). The present records of Umbilibalcis lata represents the first record of the the genus in the southwestern Atlantic.
The present genus resembles Niso by the presence of microscopic sculpture of axial lines on the protoconch and teleoconch, but has a more rounded base and edge of the umbilicus, and lacks color on the teleoconch. Furthermore, the aperture of Umbilibalcis is more rounded, while in Niso it is usually rhomboid.