Rhinoraja longi, a new species of skate from the outer Aleutian Islands, with comments on the status of Rhinoraja (Chondrichthyes, Rajoidei)

Discovery of a new species of skate, Rhinoraja longi, from the outer Aleutian Islands led to a re-evaluation of the status and species composition of this genus. Rhinoraja is presently distinguished from Bathyraja primarily by its basally segmented rostral shaft and slightly longer tail. The genus contains five species plus the new species, and is endemic to the North Pacific arc, from Hokkaido, Japan, to the Aleutian Islands. The six species are very similar in morphology, meristics, and skeletal structure but differ substantially from each other in dermal denticle characters. Salient features of systematic significance in the dermal skeleton include the density and the relative proportions of total height, base height, and crown height of the denticles. The number and distribution of normal and alar thorns are also important.