First recording of Succinea Draparnaud, 1801 for the Holocene of the Lerma Valley, NW, Argentina

PEDRO DANTE RUIZ; LEONARDO ELÍAS; PABLO RAMOS; EMANUEL LEGUIZAMÓN; SANTIAGO RETAMOSO; PEREZ, DAMIÁN EDUARDO

Congreso; 2nd Palaeontological Virtual Congress; 2020

Here we present the first record of land snails of the genus Succinea (Eupulmonata: Succineidae) for the Holocene of the Lerma Valley in Salta province, NW Argentina. In this intermontane basin, three units have been described for the Quaternary: the Calvimonte, Tajamar, and La Viña formations. In the south of the valley, the La Viña Formation outcrops expose a slightly coarsening-up sequence that corresponds to an alluvial-fluvial succession. At the Tajamar creek, the La Viña profile starts with a paleochannel filled with white-greyish volcanic ashes (0.1?0.04 Ma), continues with a few meters of very fine and fine reddish sandstones with intercalations of fine gravel lenses with a sandy matrix. The sequence ends with a lenticular level of white volcanic ashes (5130 ± 250 and 3920 ± 190 years) and around one meter of medium sandstone. Immediately above the younger level of ashes, in a bank of fine reddish sandstone, one very small shell (maximum length 6 mm), fusiform, imperforated, with slightly inclined and deep sutures, with 3 visible slightly convex turns, whose last whorl comprises 70% of the total length, ornamented on surface only by growth lines was found and assigned to the genus Succinea. Living representatives of this genus inhabit non-marine water or water-related environments, and the paleoenvironment interpreted for La Viña Formation matches with these requirements. This is the first record from Salta, and the northernmost of the Holocene distribution in Argentina for this genus.