Oregonia

Life-forms

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Ecdysozoa
Cladus: Panarthropoda
Phylum: Arthropoda
Subphylum: Crustacea
Superclassis: Multicrustacea
Classis: Malacostraca
Subclassis: Eumalacostraca
Superordo: Eucarida
Ordo: Decapoda
Subordo: Pleocyemata
Infraordo: Brachyura
Sectio: Eubrachyura
Subsectio: Heterotremata
Superfamilia: Majoidea

Familia: Oregoniidae
Genus: Oregonia
Species (3): O. bifurca – O. gracilis – †O. spinifera

Check: O. hirta – O. kurilensis – O. longimana
Name

Oregonia Dana, 1851

Primary references

Dana 1851: Amer. J. Sci., (2) 11, 270

Oregonia is a genus of crabs, comprising two extant species[1] and one fossil species:[2] It is classified in the family Oregoniidae under the spider crab superfamily Majoidea.[1]
Description

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
Oregonia gracilis Dana, 1851 – the graceful decorator crab, found in shallow waters of the northern Pacific Ocean, from off Japan to the waters off California
†Oregonia spinifera Schweitzer, Feldmann, González-Barba & Vega, 2002[5] – a fossil species from the Oligocene El Cien Formation of Baja California, Mexico[6]

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]
See also

Decorator crab

References

Peter Davie (2010). "Oregonia Dana, 1851". WoRMS. World Register of Marine Species. Retrieved January 11, 2012.
Sammy De Grave; N. Dean Pentcheff; Shane T. Ahyong; et al. (2009). "A classification of living and fossil genera of decapod crustaceans" (PDF). Raffles Bulletin of Zoology. Suppl. 21: 1–109.
Mary J. Rathbun (1925). The Spider Crabs of America (PDF). Bulletin (United States National Museum) 129. Washington: Government Printing Office. pp. 71–79.
John S. Garth (1958). Brachyura of the Pacific Coast of America, Oxyrhyncha (PDF). Allan Hancock Pacific Expeditions. Volume 21, Part 1. Los Angeles: The University of Southern California Press. pp. 135–141.
Francisco J. Vega, Torrey G. Nyborg and María Del Carmen Perrilliat (2006). "Mesozoic and Tertiary decapod Crustacea from Mexico". Topics in Geobiology. Studies on Mexican Paleontology. Vol. 24. pp. 79–100. doi:10.1007/1-4020-3985-9_5. ISBN 1-4020-3882-8.
Carrie E. Schweitzer; Rodney M. Feldmann; Gerardo González-Barba; Francisco J. Vega (2002). "New crabs from the Eocene and Oligocene of Baja California Sur, Mexico and an assessment of the evolutionary and paleogeographic implications of Mexican fossil decapods" (PDF). Journal of Paleontology. 76 (6 (Suppl.)): 1–43. doi:10.1666/0022-3360(2002)76[1:ncftea]2.0.co;2. S2CID 128993593.
Masatsune Takeda (1987). "Oregonia mutsuensis Yokoya, 1928, as a synonym of O. gracilis Dana, 1851" (PDF). Zoology, National Science Museum, Tokyo. 20: 133–136.