Two new species of Cenomanocarcinus VAN STRAELEN, 1936 (Decapoda: Brachyura: Paleocorystoidea) from the Lower and Middle Cretaceous of Texas, USA, with remarks on intraspecific variation in Cenomanocarcinus

摘要

Two new species of Cenomanocarcinus from the Cretaceous of Texas are described. Cenomanocarcinus cookseyi n. sp. was discovered in the Walnut Formation (Albian) of Williamson County, Texas, and is described on the basis of a single well-preserved specimen. Cenomanocarcinus boedekeri n. sp. was found in the Woodbine Formation (middle Cenomanian) of Dallas County, Texas and is erected on the basis of a re-examination of Cenomanocarcinus specimens from that stratigraphic unit. In addition, the existence of two well-defined lineages is proposed based on a comparison between the new species and all previously known Cenomanocarcinus species.