Portunoidea.html



Portunoidea
Portumnus latipes of the Portunidae
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Subphylum: Crustacea Class: Malacostraca Subclass: Eumalacostraca Superorder: Eucarida Order: Decapoda Suborder: Pleocyemata Infraorder: Brachyura Section: Eubrachyura Subsection: Heterotremata Superfamily: Portunoidea Rafinesque, 1815
Families
4, and see text

Portunoidea is a superfamily of crabs. They are close relatives of the Xanthoidea¹, and the family Hexapodidae, usually included there, is sometimes placed in the Portunoidea. Apart from the freshwater family Trichodactylidae, they all live in the ocean.

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.¹

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.¹

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.¹

Families

There are four living families placed here:

• Geryonidae Colosi, 1923 – deepsea crabs
• Portunidae – swimming crabs
• Trichodactylidae Milne Edwards, 1853
• Mathildellidae Karasawa & Kato, 2003

In addition, there is one prehistoric family from the Cretaceous tentatively placed here:¹

• Carcineretidae

If these are indeed correctly assigned here, the Torynommidae (another extinct family) ought to be placed in the Portunoidea too.¹

Footnotes

References

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Portunoidea

• Karasawa, Hiroaki & Schweitzer, Carrie E. (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. PDF fulltext