The genus Leptomaria E Eudes-Deslongchamps, 1864 (Gastropoda, Pleurotomariidae) from the Early Bajocian of Luxembourg: systematics and paleobiogeography.

Four species of the pleurotomariid genus Leptomaria E Eudes-Deslongchamps, 1864 are reviewed based on previously undescribed material from Bajocian deposits of the eastern Paris Basin. One of them, Leptomaria nicsimoni sp. nov., is introduced as a new species. A critical revaluation of the literature shows that Leptomaria has been broadly interpreted in the past, in contrast with the rather detailed description given by its author. This focused on shell characters, such as the width and position of the slit and selenizone, which have been overlooked by most subsequent authors. A revised diagnosis that reintroduces these characters is presented on the basis of the Bajocian material studied and of a survey of the relevant literature. This diagnosis, which is based also on other characters not considered before, excludes from Leptomaria several species previously assigned to it. The genus occurred from the Middle Aalenian to the Cenomanian mainly in the epicontinental seas of western Europe. It experienced a peak of diversity in the Bajocian, followed by a slow decline in Bathonian to Callovian times concomitantly with the appearance of the genus in the south-eastern margin of Tethys. Records in Upper Jurassic to Cretaceous sediments are sparse.