The nuculanids Leda mendax Meneghini in Appelius, 1871, from the Plio-Pleistocene of Italy and Leda reussi Hörnes, 1865, from the Middle Miocene of Austria, are almost equilateral in shape, not rostrate, with a very shallow pallial sinus and a posterior radial swelling terminating in a rounded postero-ventral projection. Such a combination of shell characters is known only in these two species. For them, Dyolia n. gen. is proposed, with Leda mendax as type species. Relations with other nuculanids and the origin of Dyolia n. gen. are unclear. Taphonomic and morphofunctional observations on Dyolia mendax and D. reussi point to a specialization for muddy, soupy bottoms of the inner shelf, as shallow borrowers.