ON THE GENERIC STATUS OF PALAEOPHICHTYHYS PARVULUS EASTMAN 1908 AND MONONGAHELA-STENODONTA LUND 1970 (OSTEICHTHYES, DIPNOI)

The genus Monongahela Lund 1970, a species of dipnoan based on small t ooth plates from the Duquesne limestone, Upper Pennsylvanian, in Mount Washington, Allegheny County, Pennsylvania, has been designated a jun ior synonym of Palaeophichthys parvulus Eastman 1908. Alternative inte rpretations of the material are, however, possible. Palaeophichthys pa rvulus is known from two juvenile specimens from the Francis Creek sha le, Carbondale Formation, Middle Pennsylvanian, in the Mazon Creek are a of Grundy County, Illinois. These are compressed, with macerated hea ds. The holotype has poorly preserved upper and lower tooth plates. Ch aracters for comparison with Monongahela can be derived only from the upper tooth plates. None of the tooth plate characters that can be rel iably distinguished in P. parvulus are sufficient to separate this spe cies from a range of other lungfish genera, and both taxa are found at localities where other dipnoan genera occur. Because additional mater ial and definition of all of the lungfish in the localities are needed to settle the question of congenerity of Palaeophichthys and Monongah ela, separation of the two genera should be retained at present.