New genera and species of glaessneropsid crabs from the Lower and Middle Jurassic of France and Germany-Austria, and reconsolidation of Charassocarcinus Van Straelen, 1925

Abstract

A new genus, Meroncarcinus, and two new species, M. boursicoti and Verrucarcinus marsae, are described from Callovian (Middle Jurassic) deposits of Calvados and Maine-et-Loire, France. New material of the type species of the genus Verrucarcinus, V. torosus, is examined, which improves our understanding of the peculiar morphology of this group of crabs. A new genus and species, Vilsercarcinus keuppi, is recognised from Lower-Middle Jurassic strata of Germany-Austria. Charassocarcinus, a Lower-Middle Jurassic crustacean genus of doubtful taxonomic affinity, is revived and here assigned to the Glaessneropsidae. All of this material forms the basis for a re-examination of the Glaessneropsidae, and an enhanced diagnosis is compiled. The morphology of Glaessneropsidae, one of the oldest known brachyuran families, is discussed; its complex orbital structure is remarkable for such an ancient group of crab and raises questions about its relationship with the basal brachyuran group Homolodromioidea. A solid support for a suprafamilial rank for the Glaessneropsidae is lacking.