Bollettino della Società Paleontologica Italiana, 48 (1), 2009, 51-57. Modena, 15 maggio 200951 Two new species of Rissoina (Gastropoda: Rissoidae) in the Lower Miocene of Valle Ceppi (Torino, NW Italy) Marta ZUNINO & Giulio PAVIA M. Zunino, Dipartimento di Scienze della Terra, Università degli Studi di Torino, Via Valperga Caluso 35, I-10125 Torino, Italy;
[email protected] G. Pavia, Dipartimento di Scienze della Terra, Università degli Studi di Torino, Via Valperga Caluso 35, I-10125 Torino, Italy;
[email protected] KEY WORDS - Rissoidae, Rissoina, Lower Miocene, Valle Ceppi, Torino Hills, Tertiary Piedmont Basin. ABSTRACT - Two new species of Rissoina from the Miocene of Torino Hills, Rissoina (R.) giuntellii and Rissoina (R.) sturanii, are described in this paper. Rissoina (R.) giuntellii n. sp. is frequent in the Lower Miocene deposits of Valle Ceppi and in coeval and more recent layers of Torino Hills; it is characterized by a small shell with convex whorls, the sculpture is composed by prominent axial ribs and cords visible at the base of the last whorl. Rissoina (R.) sturanii n. sp. is only known from the Valle Ceppi section; it is characterized by medium-sized shells with flat whorls and very fine axial and spiral ornamentation. Because of the reduced number of specimens and their state of conservation, scanning electron microscope photographs were used to study shell micro-architecture where possible. Comparison with the coeval Rissoininae known from the deposits of Paratethys, Aquitaine Basin and Loire Basin confirmed the election of Rissoina (R.) giuntellii n. sp. and Rissoina (R.) sturanii n. sp., currently known only in the Miocene deposits of the Tertiary Piedmont Basin.