Critical review of fossil record of Ranina Lamarck, 1801 (Decapoda, Brachyura, Raninidae), with description of Tethyranina n. gen.

Abstract

Pasini and Garassino (2017a) revised the fossil record referred to Ranina Lamarck, 1801 by Karasawa et al. (2014). As result only four species were considered as possible valid species within Ranina: R. palmea E. Sismonda, 1846, R. pellattieroi De Angeli and Beschin, 2011, R. propinqua Ristori, 1891, and R. ranina (Linnaeus, 1758). These species are herein revised and discussed, based on updated observations and critical review of the fossil materials and on a re-definition of the main diagnostic proxy characters sensu Schweitzer (2003) of the type species R. ranina (Linnaeus, 1758). This review allows us to establish that R. ranina from the middle Pleistocene of Ryukyu Islands (Japan) and R. palmea from the middle Miocene of Italy have consistent proxy characters with the extant Ranina to be considered as valid species within the genus. Moreover, Tethyranina n. gen., with T. propinqua (Ristori, 1891) n. comb., is herein proposed to accommodate this questionable fossil species previously assigned to Ranina. Finally R. pellattieroi De Angeli and Beschin, 2011, lacking the typical characters of Ranina, is considered as a doubtful species within Ranininae.