Hexapodidae

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Hexapodidae
Temporal range: Paleocene–Recent
Hexapodidae (MNHN-IU-2013-1704).jpeg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Brachyura
Subsection: Heterotremata
Superfamily: Hexapodoidea
Miers, 1886  [1]
Family: Hexapodidae
Miers, 1886  [1]
Type genus
Hexapus
De Haan, 1833
Genera

See text

Hexapodidae is a family of crabs, the only family in the superfamily Hexapodoidea. [1] It has traditionally been treated as a subfamily of the family Goneplacidae, [2] and was originally described as a subfamily of Pinnotheridae.[ citation needed ] Its members can be distinguished from all other true crabs by the reduction of the thorax, such that only seven sternites are exposed, and only four pairs of pereiopods are present. [3] Not counting the enlarged pair of claws, this leaves only six walking legs, from which the type genus Hexapus, and therefore the whole family, takes its name. Some anomuran "crabs", such as porcelain crabs and king crabs also have only four visible pairs of legs. With the exception of Stevea williamsi , from Mexico, all the extant members are found either in the Indo-Pacific oceans, or around the coast of Africa. [3]

Contents

Fossil record

In addition to the extant taxa, the family contains two genera known only from fossils – Goniocypoda and Palaeopinnixa – and two further genera include both living and fossil representatives: Hexapus and Stevea . [1] The family's fossil record extents back certainly as far as the Paleocene, with unverified reports of a species in the Maastrichtian of Senegal. [3]

Genera

The following are the genera included under Hexapodidae: [3] [4] [5]

Genera marked with are extinct

Related Research Articles

<span class="mw-page-title-main">Anomura</span> Infraorder of crustaceans

Anomura is a group of decapod crustaceans, including hermit crabs and others. Although the names of many anomurans include the word crab, all true crabs are in the sister group to the Anomura, the Brachyura.

<i>Cancer</i> (genus) Genus of crabs

Cancer is a genus of marine crabs in the family Cancridae. It includes eight extant species and three extinct species, including familiar crabs of the littoral zone, such as the European edible crab, the Jonah crab and the red rock crab. It is thought to have evolved from related genera in the Pacific Ocean in the Miocene.

<span class="mw-page-title-main">Hymenosomatidae</span> Family of crabs

Hymenosomatidae is a family of crabs with some 110 described species in 24 genera. The following genera are placed in the Hymenosomatidae:

<span class="mw-page-title-main">Cancridae</span> Family of crabs

Cancridae is a family of crabs. It comprises six extant genera, and ten exclusively fossil genera, in two subfamilies:

Hexapus is a genus of crabs in the family Hexapodidae. It contains only three extant species found in the Indo-West Pacific. They inhabit the intertidal and subtidal areas of shorelines.

Etyiidae is a prehistoric family of dromiacean crabs only known from Cretaceous and a few Paleocene fossils.

<span class="mw-page-title-main">Dromiacea</span> Group of crabs

Dromiacea is a group of crabs, ranked as a section. It contains 240 extant and nearly 300 extinct species. Dromiacea is the most basal grouping of Brachyura crabs, diverging the earliest in the evolutionary history, around the Late Triassic or Early Jurassic. Below is a cladogram showing Dromiacea's placement within Brachyura:

<span class="mw-page-title-main">Homolodromiidae</span> Family of crabs

Homolodromiidae is a family of crabs, the only family in the superfamily Homolodromioidea. In contrast to other crabs, including the closely related Homolidae, there is no strong linea homolica along which the exoskeleton breaks open during ecdysis. The family comprises two genera, Dicranodromia, which has 18 species, and Homolodromia, with five species.

<span class="mw-page-title-main">Carpilioidea</span> Superfamily of crabs

Carpilioidea is a superfamily of crabs containing a single extant family, Carpiliidae and three extinct families. The modern range of the family includes the Indo-Pacific, Western Atlantic and Caribbean Sea. The fossil record of the group extends back at least as far as the Paleocene.

<span class="mw-page-title-main">Goneplacidae</span> Family of crabs

Goneplacidae is a family of crabs of the order Decapoda and the superfamily Goneplacoidea. It includes the following genera:

<span class="mw-page-title-main">Eubrachyura</span> Group of crabs

Eubrachyura is a group of decapod crustaceans comprising the more derived crabs. It is divided into two subsections, based on the position of the genital openings in the two sexes. In the Heterotremata, the openings are on the legs in the males, but on the sternum in females, while in the Thoracotremata, the openings are on the sternum in both sexes. This contrasts with the situation in other decapods, in which the genital openings are always on the legs. Heterotremata is the larger of the two groups, containing the species-rich superfamilies Xanthoidea and Pilumnoidea and all the freshwater crabs. The eubrachyura is well known for actively and constantly building its own burrows. The fossil record of the Eubrachyura extends back to the Cretaceous; the supposed Bathonian representative of the group, Hebertides jurassica, ultimately turned out to be Cenozoic in age.

<i>Metacarcinus</i> Genus of crabs

Metacarcinus is a genus of crabs formerly included in the genus Cancer. It includes nine exclusively fossil species and five extant species, of which four are also known from the fossil record. A molecular study using the cytochrome oxidase I gene does not support the monophyly of this genus.

<span class="mw-page-title-main">Corystidae</span> Family of crabs

Corystidae is a family of crabs, in its own superfamily, Corystoidea. It includes what was once thought to be the oldest Eubrachyuran fossil, Hebertides jurassica, thought to be dating from the Bathonian ; the species was subsequently reinterpreted as being Cenozoic in age. Corystidae contains ten extant and five extinct species in eight genera:

<span class="mw-page-title-main">Cheiragonidae</span> Family of crabs

Cheiragonidae is a small family of crabs, sometimes called helmet crabs, placed in its own superfamily, Cheriagonoidea. It comprises three extant species, Erimacrus isenbeckii, Telmessus acutidens and Telmessus cheiragonus, there are no yet evidences of Cheiragonidae in the fossil record. Many of these crabs were formerly treated as members of the Atelecyclidae.

<span class="mw-page-title-main">Pilumnoidea</span> Superfamily of crabs

Pilumnoidea is a superfamily of crabs, whose members were previously included in the Xanthoidea. The three families are unified by the free articulation of all the segments of the male crab's abdomen and by the form of the gonopods. The earliest fossils assigned to this group are of Eocene age.

<span class="mw-page-title-main">Matutidae</span> Family of crabs

Matutidae is a family of crabs, sometimes called moon crabs, adapted for swimming or digging. They differ from the swimming crabs of the family Portunidae in that all five pairs of legs are flattened, rather than just the last pair, as in Portunidae. Crabs in the Matutidae are aggressive predators.

<span class="mw-page-title-main">Pseudozioidea</span> Superfamily of crabs

Pseudozioidea is a superfamily of crabs, formerly treated in the Eriphioidea, Carpilioidea, Xanthoidea, Pilumnoidea and Goneplacoidea. A number of fossils from the Eocene onwards are known from the family Pseudoziidae. Eleven genera are recognised in three families:

<span class="mw-page-title-main">Galatheoidea</span> Superfamily of crustaceans

The Galatheoidea are a superfamily of decapod crustaceans comprising the porcelain crabs and some squat lobsters. Squat lobsters within the three families of the superfamily Chirostyloidea are not closely related to the squat lobsters within the Galatheoidea. The fossil record of the superfamily extends back to the Middle Jurassic genus Palaeomunidopsis.

<i>Polydectus</i> Genus of crabs

Polydectus cupulifer is a species of crab in the family Xanthidae, and the only species in the genus Polydectus. Together with the genus Lybia, it forms the subfamily Polydectinae. It is found in the Indo-Pacific, ranging from Madagascar and the Red Sea in the west to Japan, Hawaii and French Polynesia in the east. P. cupulifer is densely covered with setae (bristles), and frequently carries a sea anemone in each chela (claw).

<i>Speocarcinus</i> Genus of crabs

Speocarcinus is a genus of crabs in the family Xanthidae, containing six extant species, one fossil species from the Late Miocene, one fossil species from the Eocene (Lutetian) and one fossil species from the Early Eocene (Ypresian):

References

  1. 1 2 3 4 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. Jung-Fu Huang; Pan-Wen Hsueh; Peter K. L. Ng (2002). "Crabs of the family Hexapodidae (Decapoda: Brachyura) from taiwan, with description of a new genus and new species" (PDF). Journal of Crustacean Biology . 22 (3): 651–660. doi: 10.1163/20021975-99990277 .
  3. 1 2 3 4 Carrie E. Schweitzer; Rodney M. Feldmann (2001). "Differentiation of the fossil Hexapodidae Miers, 1886 (Decapoda: Brachyura) from similar forms" (PDF). Journal of Paleontology . 75 (2): 330–345. doi:10.1666/0022-3360(2001)075<0330:DOTFHM>2.0.CO;2.
  4. Dwi Listyo Rahayu; Peter K. L. Ng (2014). "New genera and new species of Hexapodidae (Crustacea, Brachyura) from the Indo-West Pacific and east Atlantic" (PDF). Raffles Bulletin of Zoology . 62: 396–483. Archived from the original (PDF) on 2014-12-15. Retrieved 2014-12-15.
  5. Antonio De Angeli; Danièlle Guinot; Alessandro Garassino (2010). "New hexapodid crabs from the Eocene of Vicenza (NE Italy) (Crustacea, Decapoda, Brachyura, Hexapodidae)" (PDF). Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano. 151 (1): 51–75.