Evaluation of extinct members of Asthenognathinae (Decapoda: Brachyura: Varunidae) based on new specimens from the Astoria Formation (Miocene), Oregon, USA

Abstract

Only two genera are currently referred to Asthenognathinae, one extinct, Globihexapus Schweitzer and Feldmann, 2001, and the other ranging from Oligocene to Holocene, Asthenognathus Stimpson, 1858. Asthenognathinae is currently recognized as a member of Varunidae. New specimens of Globihexapus from the Miocene Astoria Formation, Newport, Oregon, are more complete than the original material and permit more detailed description of the type species. Globihexapus shares many features with Asthenognathus and is confirmed as member of that subfamily. A detailed diagnosis for the Asthenognathinae is provided, possibly for the first time. Latitudinal range for members of Asthenognathinae have broadened in the Holocene to include tropical occurrences, whereas southern hemisphere occurrences are not recorded today. No ev-idence of commensal lifestyle is reported for fossil occurrences.