Majoidea

"Spider crabs" redirects here. For spiders of the family Thomisidae, see crab spider.

Majoidea Temporal range: Cenomanian–Recent PreꞒ Ꞓ O S D C P T J K Pg N
Macropodia rostrata (Inachidae)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Malacostraca
Order:	Decapoda
Suborder:	Pleocyemata
Infraorder:	Brachyura
Subsection:	Heterotremata
Superfamily:	Majoidea Samouelle, 1819

The Majoidea are a superfamily of crabs which includes the various spider crabs.

Taxonomy

In "A classification of living and fossil genera of decapod crustaceans" De Grave and colleagues divided Majoidea into six families:^[1]

• Family Epialtidae
  • Subfamily Epialtinae
  • Subfamily Pisinae
  • Subfamily Pliosomatinae
  • Subfamily Tychiinae
• Family Hymenosomatidae
• Family Inachidae
• Family Inachoididae
• Family Majidae
  • Subfamily Eurynolambrinae
  • Subfamily Majinae
  • Subfamily Micromaiinae
  • Subfamily Mithracinae
  • Subfamily Planoterginae
• Family Oregoniidae

The classification has since been revised, with subfamilies Epialtinae and Mithracinae being elevated to families and Hymenosomatidae being moved to its own superfamily. The family composition according to the World Register of Marine Species is as follows:^[2]

• family Epialtidae MacLeay, 1838
• family Inachidae MacLeay, 1838
• family Inachoididae Dana, 1851
• family Macrocheiridae Dana, 1851
• family Majidae Samouelle, 1819 – "true" spider crabs
• family Mithracidae Balss, 1929
• family Oregoniidae Garth, 1958
• family †Priscinachidae Breton, 2009

Notable species within the superfamily include:

• Japanese spider crab (Macrocheira kaempferi), the largest living species of crab, found on the bottom of the Pacific Ocean.
• Libinia emarginata, the portly spider crab, a species of crab found in estuarine habitats on the east coast of North America.
• Hyas, a genus of spider crabs, including the great spider crab (Hyas araneus), found in the Atlantic and the North Sea.
• Maja squinado, sometimes called the "European long leg crab or pie faced crab" because of the way its face is shaped.
• Australian majid spider crab, found off Tasmania, are known to pile up on each other, the faster-moving crabs clambering over the smaller, slower ones.^[3]

There is one fossil family, Priscinachidae, represented by a single species, Priscinachus elongatus, from the Cenomanian of France.^[4]

• 
  Hoplophrys oatesi, an Epialtidae
• 
  Limnopilos naiyanetri, a Hymenosomatidae
• 
  Macrocheira kaempferi, an Inachidae
• 
  Pyromaia cuspidata, an Inachoididae
• 
  Maja squinado, a Majidae
• 
  Hyas coarctatus, an Oregoniidae

References

1. 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. Archived from the original (PDF) on 2011-06-06.
2. WoRMS. "Majoidea Samouelle, 1819". World Register of Marine Species. Retrieved 23 December 2022.
3. Martha Holmes & Michael Gunton (2009). Life: Extraordinary Animals, Extreme Behaviour. London: BBC Books. ISBN 9781846076428.
4. Gérard Breton (1 September 2009). "Description of Priscinachus elongatus n. gen., n. sp., and Priscinachidae n. fam. for the earliest spider crab (Crustacea, Decapoda, Majoidea), from the French Cretaceous (Cenomanian)" (PDF). Geodiversitas (in French and English). 31 (3): 509–523. doi:10.5252/g2009n3a2. S2CID 85827715.