Cenozoic Muricidae of the Western Atlantic Region Part IV - Hexaplex and Murexiella
AbstractThis report covers two closely related genera of Muricinae, Hexaplex and Murexiella, including the subgenera Hexaplex (Murexsul) and Murexiella (Subpterynotus), in the Cenozoic of the western Atlantic region. A total of 28 species are treated systematically; of these twelve are referred to Hexaplex s.s., one to Hexaplex (Murexsul), fourteen to Murexiella s.s. and one to Murexiella (Subpterynotus). Of this number, only two species of Hexaplex s.s. and four of Murexiella s.s., or six species in all, occur in the Recent of the western Atlantic region and of these only three species are confined to Recent waters, the other three having fossil representatives also. The genera Hexaplex s.s. and Murexiella s.s. are well represented in the Eocene of both the New World and the Old World; but the respective subgenera do not appear until the Miocene. Subpterynotus is evidently extinct in the western Atlantic, but there is one Recent species, probably Indo-Pacific in distribution, referable to the subgenus. Seven new species are described herein: Hexaplex (Hexaplex) texanus from the Weches Formation of Texas, and H. (H.) katherinae from the Moodys Branch Marl of Mississippi and Louisiana, both Eocene in age; H. (H.) etheringtoni, from the Tubera Group of Bolivar, Colombia, H. (Murexsul) thalmanni and Murexiella (Murexiella) veracruzana, both from the Agueguexquite Formation of Vera Cruz, Mexico, and M. (M.) calhounensis, from the Chipola Formation of Florida, all Miocene in age; and M. (M.) petiti from the Pliocene Waccamaw Formation of South Carolina.