Cenozoic Muricidae of the Western Atlantic Region Part III - Chicoreus (Phyllonotus)

Abstract

There are 18 species of the muricine subgenus Phyllonotus recognized in the Cenozoic of the western Atlantic region; three of these species are extant. The earliest known species here referred to Phyllonotus is from the lower Oligocene Red Bluff Clay of Mississippi. The group is believed to have been derived from a Hexaplex ancestor because of similarities of protoconch type in the earlier fossil species and of coloration in the Recent species. Phyllonotus is thought to have given rise to the subgenera Chicorenus s.s. and Siratus. An endemic western Atlantic form, Phyllonotus migrated through the Isthmian passage, probably in the Miocene time, and evolved into the four species presently known from the eastern Pacific. The subgenus is and has always been confined to the New World. All 18 western Atlantic Cenozoic species are treated systematically, including one new species Chicoreus (Phyllonotus) leonensis E. H. Vokes, from the Choctawhatchee Formation of northern Florida.