A new large mound dwelling chiton (Mollusca), from the Late Ordovician Boda Limestone of central Sweden

Abstract

A new rare Upper Ordovician mound dwelling palaeoloricate chiton is described as <i>Crassaplax collicola</i> gen. et sp. nov. from three large isolated intermediate valves from the Katian carbonate mud mounds of the Boda Limestone in the Siljan district of central Sweden. Together with the previously known <i>Spicuchelodes</i>? sp., also from the Boda Limestone, these are the only known Late Ordovician mound dwellers so far among the palaeoloricates, adding to Ordovician environments with reported chiton remains. <i>Crassaplax collicola</i> is distinguished from other Ordovician palaeoloricate chitons by their thick and large valves that can be 2 cm in length, and especially the clear differentiation between the lateral and central valve areas.