Porterius, COWLITZENSIS, CLARK, 1925

Hickman, Carole S., 2023, Paleogene marine bivalves of the deep-water Keasey Formation in Oregon, Part II: The pteriomorphs, PaleoBios 40 (5), pp. 1-51 : 14

PORTERIUS ? COWLITZENSIS

( WEAVER AND PALMER, 1922)

Arca (Barbatia) cowlitzensis Weaver and Palmer (1922) , p. 9; pl. 8, fig. 9.

Arca (Barbatia) cowlitzensis Weaver and Palmer, Weaver (1943) . pp. 67–68; pl. 12, fig. 13.

Porterius cowlitzensis (Weaver and Palmer) , Reinhart (1943). pp. 85–86; pl. 2, fig. 5)

Discussion— A poorly-known species, based on a single specimen from the middle Eocene Cowlitz Formation in Washington, is similar in shape to Porterius gabbi but clearly distinguished by very fine radial sculpture. The Cowlitz is a middle Eocene tropical marine deltaic complex (Nesbitt, 1995) intermediate in age between the Ardath Shale and the Keasey Formation. Reinhart (1943) noted the similarity of the Cowlitz shell to P. woodfordi and assigned the species to Porterius although the hinge plate is not exposed. Because it is impossible to distinguish some species of Barbatia from those of Porterius without knowledge of the hinge teeth, the generic assignment of the Cowlitz species remains in doubt. The holotype is larger than any of the known specimens of P. woodfordi , but it is possible that it represents the same species or is part a Paleogene species complex.