Debrunia, a new Barremian genus of petalodontid Monopleuridae (Bivalvia, Hippuritoidea) from the Mediterranean region

Debrunia gen. nov. is characterized by asymmetric myophoral apophyses on the left valve: the posterior one a plate, the anterior a crest. The myophores on the right valve are on the shell wall. It belongs to a group of cylindro-conical petalodontid Monopleuridae including Petalodontia and Pseudopetalodontia, and possesses some affinities with Agriopleura. Monopleura mutabilis Matheron is the type species of Debrunia gen. nov., and Monopleura (Petalodontia) bruni Douville is also ascribed to this genus. The two species are found in late Barremian beds from SE France. Evolutionary trends regarding the myophores of the left valve are comparable and nearly coeval with those of Agriopleura. Debrunia may be the root of the late Aptian-Albian genera Pseudopetalodontia and Mathesia. and may range throughout the Barremian-Aptian.