Portunoidea

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Ecdysozoa
Cladus: Panarthropoda
Phylum: Arthropoda
Cladus: Pancrustacea
Superclassis: Multicrustacea
Classis: Malacostraca
Subclassis: Eumalacostraca
Superordo: Eucarida
Ordo: Decapoda
Subordo: Pleocyemata
Infraordo: Brachyura
Sectio: Eubrachyura
Subsectio: Heterotremata
Superfamilia: Portunoidea
Familiae (13): Brusiniidae – †Carcineretidae – Carcinidae – †Dinocarcinus – †Eogeryonidae – Geryonidae – †Litophylacidae – †Longusorbiidae – Nautilocorystidae – Ovalipidae – Pirimelidae – Polybiidae – Portunidae – †Psammocarcinidae – Thiidae

Name

Portunoidea Rafinesque, 1815

References
Primary references

Rafinesque, C.S. 1815. Analyse de la nature, ou tableau de l'univers et des corps organisés. Palerme: L'Imprimerie de Jean Barravecchia. 224 pp. BHL Reference page.

Additional references

Evans, N.M. 2018. Molecular phylogenetics of swimming crabs (Portunoidea Rafinesque, 1815) supports a revised family-level classification and suggests a single derived origin of symbiotic taxa. PeerJ. 6: e4260. DOI: 10.7717/peerj.4260 Open access Reference page. [See p. 25]

Portunoidea is a superfamily of crabs that includes the family Portunidae, the swimming crabs. Which other crab families are also placed here is a matter of some contention, and may be revised following molecular phylogenetic analyses.[1]
Description

Their rather flat and smooth carapace is usually wider than long and of hexagonal, subhexagonal, rectangular, or transversely ovate shape. It is usually widest between the hindmost spines of the forward rim; there may be up to 9 pairs of these spines, with a few smaller ones right above the head, but they are missing altogether in some species.[2]

In some, the first maxilliped's endopod is lobed, forming the characteristic portunid lobe. The chelipeds are usually robust, and in some the last pereiopod pair has ovate dactyls. The sutures of the sternum between segments 4 to 8 are usually incomplete, and in the Portunidae, the eighth sternite is usually visible if seen from below and has a penial groove.[2]

In males, the abdominal somites are either all free or the third to fifth are fused, often retaining the sutures though. The first gonopod is strongly curved, with a swollen and strongly hooked base.[2]
Classification
Representative putative symbiotic Thalamitinae species

Portunoidea are close relatives of the Xanthoidea,[2] and the families Hexapodidae and Mathildellidae, usually included there, are sometimes placed in the Portunoidea, while the deep-sea crabs (Geryonidae) are usually placed in the Portunoidea but sometimes in the Xanthoidea. All Portunoidea live in the ocean, although the family Trichodactylidae, sometimes included here, live in fresh water.

According to the latest synopsis, there are eleven families in the superfamily Portunoidea, four of which are extinct:[1]

Carcinidae
Carcineretidae (extinct)
Catoptridae
Geryonidae
Lithophylacidae (extinct)
Longusorbiidae (extinct)
Macropipidae
Pirimelidae
Portunidae
Psammocarcinidae (extinct)
Thiidae

References

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.
Hiroaki Karasawa & Carrie E. Schweitzer (2006). "A new classification of the Xanthoidea sensu lato (Crustacea: Decapoda: Brachyura) based on phylogenetic analysis and traditional systematics and evaluation of all fossil Xanthoidea sensu lato". Contributions to Zoology. 75 (1/2): 23–73. doi:10.1163/18759866-0750102002. Archived from the original on 2016-03-03. Retrieved 2008-11-23.