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Astacidea; Temporal range: 279–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N Middle Permian - present
	Adriatic lobster
	Crayfish: Austropotamobius pallipes
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Malacostraca
Order:	Decapoda
Suborder:	Pleocyemata
(unranked):	Reptantia
Infraorder:	Astacidea; Latreille, 1802
Superfamilies
	Astacoidea; Enoplometopoidea; Nephropoidea; † Palaeopalaemonoidea; Parastacoidea;

Astacidea is an infraorder of decapod crustaceans including lobsters (though not "lobsters" such as the spiny lobster etc.), crayfish, and their close relatives.

Description

The Astacidea are distinguished from most other decapods by the presence of chelae (claws) on each of the first three pairs of pereiopods (walking legs), the first of which is much larger than the remaining two pairs.^[1] The last two pairs of pereiopods are simple (without claws), except in Thaumastocheles, where the fifth pereiopod may have "a minute pincer".^[2]

Distribution

Members of the infraorder Astacidea are found throughout the world – both in the oceans and in fresh water – except for mainland Africa and parts of Asia.^[3]

Classification

Astacidea belongs to the group Reptantia, which consists of the walking/crawling decapods (lobsters and crabs).^[4] Astacidea is the sister clade to the infraorder Polychelida, a small group of crustaceans restricted to deep waters. The cladogram below shows Astacidea's placement within the larger order Decapoda, from analysis by Wolfe et al., 2019.^[5]

Decapoda

	Dendrobranchiata (prawns)

Pleocyemata

Stenopodidea (boxer shrimp)

	Procarididea

	Caridea ("true" shrimp)

Reptantia

Achelata (spiny lobsters and slipper lobsters)

	Polychelida (benthic crustaceans)

	Astacidea (lobsters and crayfish)

Axiidea (mud shrimp, ghost shrimp, and burrowing shrimp)

Gebiidea (mud lobsters and mud shrimp)

	Anomura (hermit crabs and allies)

	Brachyura ("true" crabs)

(crawling /
walking
decapods)

The infraorder Astacidea comprises five extant superfamilies, two of crayfish (Astacoidea and Parastacoidea), one of true lobsters (Nephropoidea), one of reef lobsters (the genus Enoplometopus), and a number of fossil taxa.^[6] As of 2009^[update], the group contains 782 recognised species, over 400 of which are in the crayfish family Cambaridae.^[6] The members of the infraorder Glypheidea (containing numerous fossils and the two extant species Neoglyphea inopinata and Laurentaeglyphea neocaledonica) were formerly included here.^[1]

The cladogram below shows Astacidea's internal relationships and the early split between lobsters and crayfish:^[5]^[7]^[8]

Astacidea

clawed lobsters

Enoplometopoidea	Enoplometopidae

Nephropoidea	Nephropidae

	Astacidae

	Cambaridae

Taxonomy

Palaeopalaemonoidea †
1. Palaeopalaemonidae †
Enoplometopoidea
1. Enoplometopidae
2. Uncinidae †
Nephropoidea
1. Chilenophoberidae †
2. Nephropidae
3. Protastacidae †
4. Stenochiridae †
Astacoidea^[7]
1. Astacidae
2. Cambaridae
3. Cambaroididae
4. Cricoidoscelosidae †
Parastacoidea
1. Parastacidae

References

^ ^a ^b Gary Poore (2004). "Astacidea – scampi & crayfish". Marine Decapod Crustacea of Southern Australia: a Guide to Identification. CSIRO Publishing. pp. 159–167. ISBN 9780643099258.
^ Lipke Holthuis (1991). "Infraorder Astacidea Latreille, 1802". FAO species catalogue Vol. 13: Marine Lobsters of the World (PDF). Rome, Italy: Food and Agriculture Organization. pp. 19–86. ISBN 92-5-103027-8.
^ J. K. Lowry (October 2, 1999). "Astacidea (Decapoda, Eucarida, Malacostraca)". Crustacea, the Higher Taxa. Australian Museum. Archived from the original on July 5, 2008. Retrieved October 24, 2012.
^ Yeo, Darren; Cumberlidge, Neil; Klaus, Sebastian (2014). Advances in Freshwater Decapod Systematics and Biology. BRILL. ISBN 9789004207615.
^ ^a ^b Wolfe, Joanna M.; Breinholt, Jesse W.; Crandall, Keith A.; Lemmon, Alan R.; Lemmon, Emily Moriarty; Timm, Laura E.; Siddall, Mark E.; Bracken-Grissom, Heather D. (24 April 2019). "A phylogenomic framework, evolutionary timeline and genomic resources for comparative studies of decapod crustaceans". Proceedings of the Royal Society B. 286 (1901). doi:10.1098/rspb.2019.0079. PMC 6501934. PMID 31014217.
^ ^a ^b 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. Retrieved 2010-02-22.
^ ^a ^b Crandall, Keith A.; De Grave, Sammy (2017). "An updated classification of the freshwater crayfishes (Decapoda: Astacidea) of the world, with a complete species list". Journal of Crustacean Biology. 37 (5). doi:10.1093/jcbiol/rux070.
^ Heather D. Bracken-Grissom; Shane T. Ahyong; Richard D. Wilkinson; Rodney M. Feldmann; Carrie E. Schweitzer; Jesse W. Breinholt; Matthew Bendall; Ferran Palero; Tin-Yam Chan; Darryl L. Felder; Rafael Robles; Ka-Hou Chu; Ling-Ming Tsang; Dohyup Kim; Joel W. Martin; Keith A. Crandall (July 2014). "The Emergence of Lobsters: Phylogenetic Relationships, Morphological Evolution and Divergence Time Comparisons of an Ancient Group (Decapoda: Achelata, Astacidea, Glypheidea, Polychelida)". Systematic Biology. 63 (4): 457–479. doi:10.1093/sysbio/syu008. PMID 24562813.