PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 116(1):168-189. 2003. New brachyuran crabs (Crustacea: Decapoda) from the Upper Pliocene Yorktown Formation of southeastern Virginia Warren C. Blow Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20013-7012, U.S.A. Abstract. — Six new species of crabs, representing three families and one new genus, are described and illustrated from the Upper Pliocene Yorktown For-mation of southeastern Virginia. They are remarkable for their state of pres-ervation and represent the first fossil record for three of these living genera in Virginia's rich Neogene marine deposits. The presence of Stenocionops along with the common occurrence of Persephona in these deposits suggests that warm temperate waters covered southeastern Virginia during the deposition of late Yorktown sediments. Introduction In 1935, Mary J. Rathbun published the first comprehensive paper on the fossil crustaceans, principally decapods, of the Atlantic Gulf Coastal Plain of Eastern North America. In this landmark paper she describes or mentions all of the fossil deca-pod, stomatopod and isopod crustaceans from this region made available to her at that time from a host of sources (Rathbun 1935:1). Of the 25 families, 67 genera, and 167 species covered, and for the most part illustrated, in her paper only eight species representing six genera and six families were listed and treated from Virginia from deposits of Miocene, Pliocene and Pleisto-cene age. All but one were listed as occur-ring in deposits of the Yorktown Formation which at that time was regarded as Mio-cene. However the Neogene stratigraphy of southeastern Virginia has evolved consid-erably since 1935 (Hazel 1971a, Ward & Blackwelder 1980, Ward & Gilinsky 1993), and consequently only Cancer borealis Stimpson, 1859, Panopeus herbstii Milne-Edwards, 1834, and Libinia dubia Milne-Edwards, 1834, are listed from localities that are now regarded as old as Miocene. With the exception of Cancer borealis Stimpson, 1859, the remaining species — Callianassa sujfolkensis Rathbun, 1935; C. atlantica Rathbun, 1926; Persephona punc-tata (Linne, 1758); Callinectes sapidus Rathbun, 1896; Panopeus herbstii Milne-Edwards, 1834; and Libinia dubia Milne-Edwards, 1834 — are all listed from locali-ties now regarded as Upper Pliocene. Cal-linectes sapidus Rathbun, 1896 is the only species listed from the Pleistocene. In the present paper six additional taxa, Hepatus bottomsi, n. sp., Pterocarcinus baileyi, n. gen, n. sp., Persephona niemey-eri, n. sp., P. rodesae, n. sp., Stenocionops dyeri, n. sp., and Euprognatha ricei, n. sp. are described as new and illustrated from deposits of late Pliocene age in the same general geographic area as that treated by Rathbun 67 years ago. Unlike Rathbun 's material, which is very fragmentary, often consisting only of fingers, the taxa present-ed in this paper are remarkable for their state of preservation and completeness. All are represented by their original exoskele-ton, and many even exhibit a uniform color similar to that of their living relatives. The material studied in this paper was collected from the Moore House Member of the upper part of the Yorktown Forma-tion from three localities in southeastern
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