Bivalves from the Late Devonian pelagic or Hercynian Facies of classical regions such as eastern North America and Europe have not been investigated for almost a century.

A group of small, radially ribbed bivalves frequently occurs in association with ammonoids and conodonts in pelagic cephalopod limestones and shales of the latest Frasnian and early Famennian. These bivalves have traditionally been assigned to the Late Silurian genus Praecardium Barrande, 1881. Re-studying the types of the Late Devonian taxa, Cardium? vetustum Hall, 1843, Cardiola duplicata Münster, 1840, Praecardium clymeniae Beushausen, 1895, Praecardium melletes Clarke, 1904, and Praecardium multicostatum Clarke, 1904 shows that they differ significantly from Praecardium.

As a result, two new genera, Vetupraeca n. gen. and Mucopraeca n. gen, are established. Furthermore, neotypes are designated for Cardiola nehdensis, Kayser, 1873 and Vetupraeca clymeniae (Beushausen, 1895), and lectotypes are chosen for Mucopraeca multicostata (Clarke, 1904) and Vetupraeca duplicata (Münster, 1840). These bivalve taxa were widely distributed in the subtropical to tropical, latest Frasnian/early Famennian outer shelf habitats of Laurussia and Gondwana.