The members of the genus are characterized by subtriangular or suboblong carapaces moderately covered with small protrusions (tubercles). They have large spines on the rear margins of the eye orbits (the postorbital spine) that are situated quite far from the eyestalks. The male chelipeds are elongated. The palms (manus) of the claws are long, compressed, and widen on the outer ends. The walking legs (pereiopods) are slender and decrease in length regularly towards the back. The abdomen (pleon) has seven segments.[3][4]
Species
Three species are currently recognized under the genus:
Oregonia bifurca Rathbun, 1902 – the split-nose crab, found in deep waters of the northern Pacific Ocean, from the Bering Sea to the waters off British Columbia
The previously described species O. longimana, O. mutsuensis and O. hirta have all been subsumed into O. gracilis.[4][7]O. hirta in particular was misidentified as a separate species due to the sexual dimorphism exhibited by majoid crabs. They were actually the females of O. gracilis.[4]
^Francisco J. Vega, Torrey G. Nyborg and María Del Carmen Perrilliat (2006). "Mesozoic and Tertiary decapod Crustacea from Mexico". Topics in Geobiology. Vol. 24. pp. 79–100. doi:10.1007/1-4020-3985-9_5. ISBN1-4020-3882-8. {{cite book}}: |journal= ignored (help)