A biogenic paradigm of shells of the clavatulid gastropods: the trace fossil Clavatulicola evaephilus ichnogen. et ichnosp.n. from the Middle Miocene localities Korytnica (Holy Cross Mountains, Poland) and Grund (Vienna Basin, Austria)

Abstract

A peculiar paradigm of shells of the clavatulid gastropod (genus Clavatula LAMARCK, 1801, of the subfamily Clavatulinae, family Turridae) of Miocene age, and displayed by a pattern of furrows sculpturing preferentially the median part of the shell whorls (i.e., the anal fasciole), is ascribed to the life activity of commensals to the live gastropods. This pattern, classified as an ichnofossil, taxonomically new, Clavatulicola evaephilus ichnogen. et ichnosp.n., bears its specific name referring to the clavatulid species Clavatula evae (HOERNES & AUINGER, 1891), upon whose shells it was first presented over a century ago from Grund in the Vienna Basin, Austria. Within rich gastropod assemblages from Korytnica in the Holy Cross Mountains, Central Poland, containing a dozen or so clavatulid species, the newly established ichnotaxon is confined exclusively to the four species, viz. Clavatula evae (100% of shells infested), Cl. styriaca (100%), Cl. asperulata (92%), and Cl. suturalis (72%), what indicates a very high host specifity of the ichnofossil-producing commensals. As the potential producers of the ichnofossil pattern briefly discussed are the folliculinid infusorians and the phoronids. An attention is paid to the occurrence of the newly established ichnotaxon in the Vienna Basin fromwhere it was presented solely from the locality Grund, the gastropod assemblage of which is closest to that of Korytnica in Poland.