A new Heliacus species (Gastropoda: Architectonicidae) from the Middle Miocene marine sandy deposits of Devínska Nová Ves (Vienna Basin, Central Paratethys)

A new Middle Miocene Central Paratethyan gastropod of the family Architectonicidae Gray, 1850, Heliacus stefanmeszarosi spec. nov. is described. This small-sized architectonicid was recorded from the Upper Badenian (Serravallian) sandy marine deposits of the Stupava Formation exposed at the locality Útočnice situated at Devínska Nová Ves (Bratislava), in the Slovak part of the Vienna Basin. The placement of the species in Heliacus is based on its overall shell morphology corresponding to the genus. Comparison with other similar modern and fossil Architectonicidae members confirms that it is a distinct species with endemic distribution in the eastern margin of the Vienna Basin during the Upper Badenian. Heliacus stefanmeszarosi spec. nov. inhabited most likely shallow-water marine infralittoral paleoenvironments with soft sandy-bottom or subtidal mobile sandbanks partly with seagrass meadows influenced by higher hydrodynamics. The scleractinian assemblages of branched finger corals, Porites leptoclada (Reuss, 1871), occur in these paleoenvironments. The co-occurrence of Heliacus and Porites in the same habitat points to their possible biological interactions. Thus, the populations of Porites most probably represented hosts, a potential preferred prey of the predatory Heliacus.