Redescription of the Ordovician acrotretoid brachiopod Conotreta Walcott, 1889

The type species of the poorly understood Ordovician acrotretoid brachiopod Conotreta, C. rusti Walcott, 1889, is redescribed, based on a re-study of the syntypes and new topotypes from the Ordovician (late Mohawkian; late Ca radoc) Denmark Limestone at Trenton Falls, Mohawk River Valley, New York St ate. The numerous previous records of the genus are briefly reviewed. One s yntype of C. rusti is shown to represent the oldest recorded species of the acrotretoid (Family Biernatidae) Opsiconidion.