A NEW RANANID CRAB, RANINOIDES BOCKI (DECAPODA, CRUSTACEA) FROM THE UPPER CRETACEOUS NANAIMO GROUP, BRITISH COLUMBIA, CANADA

A new species of rananid crab, Raninoides bocki, is described from the Upper Cretaceous Nanaimo Group, Vancouver island, British Columbia, Canada.  R. bocki represents the earliest occurrence of the genus from the eastern North Pacific and worldwide. Previously assigned to the genus Rogueus based upon possession of bifid anterolateral spines, R. bocki is distinctly different from this genus and subfamily.  Along with bifid anterolateral spines species of Rogueus possess a bifid rostrum. Although R. bocki possesses similar bifid anterolateral spines similar to the genus Rogueus, R. bocki does not possess a bifid rostrum. Morphologically R. bocki is more closely aligned with the subfamily Raninoidinae and the genus Raninoides.  The shape of the dorsal carapace, placement and lengths of the frontal spines, and shape of the sternum is similar to other species of Raninoides.  The configuration of the anterolateral spines, that is distinctly bifid and stout, separate R. bocki from the other raninids.  The number, size, and position of anterolateral spines has been considered taxonomically important in raninid crabs however at least with the species assigned to the genus Raninoides, and most likely within other raninid groups, the anterolateral spines appear to be quite variable whereas other morphological portions, such as the configuration of the frontal spines, of the carapace are not.  Taxonomic assignment of new genera or placement of new species into existing genera based solely on the morphology of the anterolateral spines is questionable. Fairly complete fossil material of R. bocki allows a complete description of this new crab species providing more insight into the evolution of Raninidae.