А New Species of the Genus Lekiskochiton (Mollusca, Polyplacophora) from the Lower Permian Reef Limestones of Shakhtau (Southern Cisuralia)

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