Perforations of freshwater snail shells from the Miocene of Germany: Nihilichnus covichi n. isp.

Formerly unknown holes in shells of freshwater gastropods are described and assigned to the ichnogenus Nihilichnus. The smaller size range, the different substrate, and the sometimes present scratchings around the holes distinguish our praedichnion from the type ichnospecies N. nihilicus, and we propose N. covichi n. isp. for the herein presented material. The type material of N. covichi n. isp. derives from the middle Miocene (Mammal Neogene zones MN6 and MN7) lake sediments of the Steinheim Basin (Steinheim am Albuch, SW Germany); the holes occur in shells of Gyraulus trochiformis (Planorbidae) and Bania pseudoglobulus (Hydrobiidae). Further material consists of perforated shells of Nematurella bavarica (Hydrobiidae) and Galba armaniacensis (Lymnaeidae) from the early Miocene Kirchberg Formation (MN 4; SE Germany). In contrast to the other morphologically similar but marine praedichnia (e.g., Belichnus and Oichnus, recently synonymized with Sedilichnus), Nihilichnus is known from terrestrial, palustrine, freshwater (reported herein), and marine environments. Nihilichnus covichi n. isp. was probably produced by the pharyngeal teeth of durophagous tench fish (Tinca spp.; Cyprinidae).