A New Species of the Genus Lekiskochiton (Mollusca, Polyplacophora) from the Lower Permian Reef Limestones of Shakhtau (Southern Cis-Urals)

A new Early Permian reef-dwelling lepidopleurid chiton from Shakhtau is described as Lekiskochiton crassus sp. nov. This is one of the few Late Paleozoic chitons described from Russia and the first from the Cis-Urals. The new species is represented by the tail valve and four intermediate valves belonging to one large animal, which was found in the Asselian reef carbonates. Other scattered valves of the new species were found in younger sediments of this reef massif, in the Sakmarian Stage. All of them are preserved as imprints. The shape of the valves has been partially reconstructed. The morphological differences between the intermediate valves of a single individual of the genus are shown for the first time. L. crassus sp. nov. is the second known species of the genus, which was previously only reliably known from the type species from the Middle Permian of Texas. The new species increases the geochronological range of the genus by approximately 19 million years. In the Shakhtau polyplacophoran assemblage, in addition to the genus Lekiskochiton, the following genera have been tentatively identified: Gryphochiton, Ochmazochiton, and Pterochiton, which indicates stable biogeographical connections of the Early Permian Ural Strait with the marine basins of North America.