The modern Cumacea are a very successful group of peracaridan malacostracan crustaceans with around 1215 species (Watling, pers. comm.). Nevertheless, until now only three species of fossil cumaceans have been described, despite the fact that these forms inhabit the fine sand and coarse silts perfect for fossilization (Schram, 1986). Bachmayer, (1960) recorded a poorly preserved cumacean-like specimen Palaeocuma hessi from the Callovian, Middle Jurassic, of France. Subsequently, Malzahn (1972) studied two well-preserved Permian species of the genus Opthalmdiastylis, O. inflata and O. costata, from the marl beds of Zechstein 1, Kamp-Lintfort, Germany. These latter taxa are noteworthy in that they exhibit distinctly lobed eyes, as the generic name implies.
This paper describes three new species of Carboniferous cumaceans from the Imo Formation (Upper Mississippian) of northwestern Arkansas, and the Eudora Shale (Pennsylvanian) of southeastern Kansas. Although our specimens are not as completely preserved as the Jurassic and Permian material, nonetheless, these Carboniferous species are clearly related to the younger specimens. We effectively extend the range for the Cumacea into a time frame for which we also have the earliest fossils for other peracaridan groups, viz., the Isopoda, Tanaidacea, Pygocephalomorpha, Lophogastrida, and Spelaeogriphacea.