A new species of giant aspidoceratid Hybopeltoceras (Ammonitina) from the Lower Tithonian of the Monte Lacerone (Sabine Apennines, Central Italy)

The Upper Jurassic aspidoceratoid genus Hybopeltoceras Olóriz is very scarcely recorded, and distributed only in the Cordillera Betica (Spain), Southern Alps (Italy) and in the Central Apennines (Italy). From rocks of the Lower Tithonian, with particular reference to the Hybonotum s.s. Subzone, of the Upper Bugarone Formation in Mount Lacerone (Rieti, Sabine Apennines, Italy), the new species Hybopeltoceras olorizi is described here on the basis of a giant macroconch. The specimen is well preserved, that allows to add new data to the original Olóriz diagnosis of the genus and shows a unique morphology making the ammonite very easy to recognise. The new species shows a set of clearly recognisable phenotypical aspects strongly affected by the “Platform Effect” (sensu Olóriz). The study of calcareous nannoplankton confirm the biostratigraphic attribution.