Lobocarcinus lumacopius(Decapoda: Cancridae), a new species of cancrid crab from the Eocene of Fayum, Egypt

Abstract

The genusLobocarcinusReuss, as it is currently understood, consists of five species. Three of these species are retained:L. paulinowurtembergensis, L. indicus, andL. aegypticus. Lobocarcinus catalaunicusis referred toNeptunus, andL.? santosiis referred toCancer.A new species,L. lumacopius, is described.Lobocarcinusforms are distinct from all other cancrids in the lobation of their anterolateral margins, high width: length ratio, and dorsal carapace ornamentation. The type species of the genus,L. paulinowurtembergensis, is abundant in the Gebel Mokattam region near Cairo. The studied specimens ofL. lumacopiusare from Wadi Hitan (Zeuglodon Valley), a region approximately 140 km southwest of Gebel Mokattam in the Fayum Depression. Direct comparisons are made betweenL. lumacopiusandL. paulinowurtembergensis, and sexually dimorphic characters ofL. lumacopius, including width: length ratios and abdominal and sternal elements, are identified. A key is presented to aid in the identification of the various species within the genus and to help in distinguishingLobocarcinusfromCancer.