Biskupič R., 2023: Early ontogeny, paleoecology and intraspecific variability of two Helminthia species (Gastropoda: Turritellidae) from the Middle Miocene (Badenian) deposits of the eastern Vienna Basin (Slovakia). Acta Geologica Slovaca, 15, 1, 11–22.

Early ontogeny, paleoecology and intraspecific variability of two Helminthia species (Gastropoda: Turritellidae) from the Middle Miocene (Badenian) deposits of the eastern Vienna Basin (Slovakia)

Radoslav Biskupič

Ludvíka Svobodu 29, 058 01 Poprad, Slovakia, biskupic.radoslav@gmail.com

Abstract

An overview of the Serravallian (Middle Miocene) turritellid gastropod genus Helminthia Handmann, 1882 from the Slovak part of the Vienna Basin is presented. New records of Helminthia come from the upper Badenian (lower Serravallian) shallow- to deep sublittoral marine facies of the Studienka Formation exposed in the former clay pit and its vicinity located near the Rohožník village. Two species of Helminthia have been identified, Helminthia tricincta (Borson, 1821) and Helminthia vermicularis (Brocchi, 1814). These taxa are briefly discussed, and their stratigraphic and geographic distribution in the Miocene deposits of Slovakia is summarized. Rarely, early whorls including protoconch were recorded in examined specimens, which represent the first protoconch evidence of Helminthia from the Central Paratethys. The peculiar intraspecific variability in shells of H. tricincta is observed. Prevailing paleoecological conditions in the study area during the upper Badenian are discussed.

Key words: Helminthia, Gastropoda, paleoecology, protoconch, intraspecific variability, Miocene, Vienna Basin, Central Paratethys

Manuscript received: 2021-11-29

Revised version accepted: 2023-03-10