Cancer raninus Linnaeus, 1758: 625

Pasini, Giovanni & Garassino, Alessandro, 2018, Critical review of fossil record of Ranina Lamarck, 1801 (Decapoda, Brachyura, Raninidae), with description of Tethyranina n. gen., Natural History Sciences 5 (2), pp. 3-12 : 7-8

Cancer raninus Linnaeus, 1758: 625 (as Cancer raninus ), subsequent designation by Latreille (1810).

Ranina ranina – Oshiro & Sakida 1980, Pl. 2, fig.9. – Karasawa 1997: 39, Pl. 7, fig. 1. – Karasawa 2000: 173, Tab. 1, Pl. 2, fig. 9. – Schweitzer et al. 2010: 74. – De Angeli & Beschin 2011: 13. – Van Bakel et al. 2012: 209. – Karasawa et al. 2014: 260. – Pasini & Garassino 2015: 51. – Famiani et al. 2015: 344 (synonymies just for the fossil species).

Diagnosis: as for the genus.

Locality: Ryukyu Group of Okinawa-jima (Ryukyu Islands, Japan).

Geological age: Naha Formation (middle Pleistocene) – Recent.

Examined material: One specimen (WN-1, MFM 142326 ), original picture .

Description: Carapace incomplete, broken longitudinally, with serrate margins; widest at anterior one-quarter, narrowing posteriorly; rostrum not preserved; intra- and outer orbital spines pointed, triangular; postorbital spine divided into two spines (= bifid), with the inner spine longer; anterolateral margin with two trifid spines forward directed, the second one more inclined at about 45-degree angle to the carapace longitudinal median axis; post-frontal region slightly depressed (as preserved) below level of remainder of carapace scabrous; remainder of carapace ornamented with forward directed inclined sparse spines, sometime aligned in groups of 4-6 on the central part of the carapace.

Discussion. Oshiro & Sakida (1980) reported R. ranina from the Pleistocene of the Ryukyu Islands ( Japan) (Pl. 2, fig. 9 in Karasawa, 2000) the only fossil report for the extant species. Though incomplete, the specimen shows the main characters of the carapace of the type species R. ranina in having: a carapace widest at the anterior one-quarter, narrowing posteriorly; a bifid postorbital spine; an anterolateral margin with both two spines that are trifid and forward directed, the second one more inclined at about a 45-degree angle to the carapace longitudinal median axis; a post-frontal region depressed slightly below level of remainder of carapace, with sparse nodes; and the remainder of carapace ornamentation not uniform, with sparse forward directed inclined spines.