The new family Acutichitonidae of the suborder Lepidopleurina is erected to embrace polyplacophorans having tail valves with a terminal mucro and with lateral and posterior underturned margins (hypotyche). Aesthete canals opening on the hypotyche may have been functional and possibly served a sensory function. A polyplacophoran fauna from the Gene Autry Formation (Morrowan) of Oklahoma contains Pterochiton carbonarius (Stevens), P. tholus n. sp. and Acutichiton allynsmithi n. sp. Pterochiton carbonarius is also reported from the Smithwick Formation (upper Atokan) in Texas.--Journal abstract.