Heterotremata

Last updated

Heterotremata
Xantho poressa 2009 G2.jpg
Xantho poressa (Xanthoidea: Xanthidae)
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Brachyura
Section: Eubrachyura
Subsection: Heterotremata
Guinot, 1977
Superfamilies

See text

Heterotremata is a clade of crabs, comprising those crabs in which the genital openings are on the sternum in females, but on the legs in males. It comprises 68 families in 28 superfamilies. [1]

Contents

Evolution

Heterotremata is the sister group to Thoracotremata within the clade Eubrachyura, having diverged during the Cretaceous period. Eubrachyura itself is a subset of the larger clade Brachyura, which consists of all "true crabs". A summary of the high-level internal relationships within Brachyura can be shown in the cladogram below: [2] [3]

Brachyura

The internal relationships within Heterotremata are less certain, with many of the superfamilies found to be invalid. The proposed cladogram below is from analysis by Tsang et al, 2014: [2]

Heterotremata

Superfamilies

However, recent studies have found the following superfamilies and families to not be monophyletic, but rather paraphyletic or polyphyletic: [2] [3]

Related Research Articles

<span class="mw-page-title-main">Crab</span> Crustacean

Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting tail-like abdomen, usually hidden entirely under the thorax. They live in all the world's oceans, in freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers on each arm. They first appeared during the Jurassic period, around 200 million years ago.

<span class="mw-page-title-main">Decapoda</span> Order of crustaceans

The Decapoda or decapods are an order of crustaceans within the class Malacostraca, and includes crabs, lobsters, crayfish, shrimp, and prawns. Most decapods are scavengers. The order is estimated to contain nearly 15,000 extant species in around 2,700 genera, with around 3,300 fossil species. Nearly half of these species are crabs, with the shrimp and Anomura including hermit crabs, porcelain crabs, squat lobsters making up the bulk of the remainder. The earliest fossils of the group date to the Devonian.

<span class="mw-page-title-main">Reptantia</span> Suborder of crustaceans

Reptantia is a clade of decapod crustaceans named in 1880 which includes lobsters, crabs and many other well-known crustaceans.

<span class="mw-page-title-main">Pleocyemata</span> Suborder of crustaceans

Pleocyemata is a suborder of decapod crustaceans, erected by Martin Burkenroad in 1963. Burkenroad's classification replaced the earlier sub-orders of Natantia and Reptantia with the monophyletic groups Dendrobranchiata (prawns) and Pleocyemata. Pleocyemata contains all the members of the Reptantia, as well as the Stenopodidea, and Caridea, which contains the true shrimp.

<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.

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

The Stenopodidea or boxer shrimps are a small group of decapod crustaceans. Often confused with Caridea shrimp or Dendrobranchiata prawns, they are neither, belonging to their own group.

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

Astacoidea is superfamily of freshwater crayfish that live in the Northern Hemisphere. The other superfamily of crayfish, Parastacoidea, lives in the Southern Hemisphere. Astacoidea consists of three families: Astacidae, Cambaridae, and Cambaroididae. Crayfish are closely related to lobsters, as shown in the simplified cladogram below:

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

Astacidea is an infraorder of decapod crustaceans including lobsters, crayfish, and their close relatives.

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

Raninoida is a taxonomic section of the crabs, containing a single superfamily, Raninoidea. This group of crabs is unlike most, with the abdomen not being folded under the thorax. It comprises 46 extant species, and nearly 200 species known only from fossils.

<span class="mw-page-title-main">Eucarida</span> Superorder of crustaceans

Eucarida is a superorder of the Malacostraca, a class of the crustacean subphylum, comprising the decapods, krill, and Angustidontida. They are characterised by having the carapace fused to all thoracic segments, and by the possession of stalked eyes.

<span class="mw-page-title-main">Thoracotremata</span> Clade of crabs

Thoracotremata is a clade of crabs, comprising those crabs in which the genital openings in both sexes are on the sternum, rather than on the legs. It comprises 17 families in four superfamilies .

Cyclodorippoida is a group of crabs, ranked as a section. It contains the single superfamily Cyclodorippoidea, which holds three families, Cyclodorippidae, Cymonomidae and Phyllotymolinidae.

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

Homoloidea is a superfamily of dromiacean crabs. Homoloidea belongs the group Dromiacea, taxonomically ranked as a section, and is the sister group to Dromioidea. Dromiacea is the most basal grouping of Brachyura crabs, and likely diverged from the rest of Brachyura around the Late Triassic or Early Jurassic. The close relation between Homoloidea and Dromioidea is primarily established through ultrastructural characteristics of the sperm.

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

Dromioidea is a superfamily of crabs mostly found in Madagascar. Dromioidea belongs the group Dromiacea, taxonomically ranked as a section, which is the most basal grouping of Brachyura crabs. Dromiacea likely diverged from the rest of Brachyura around the Late Triassic or Early Jurassic, and the earliest fossils attributable to the Dromioidea date from the Late Jurassic.

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

Podotremata is a traditionally used section of crabs (Brachyura), now considered to be invalid. It was the smaller grouping of crabs, separate from the larger Eubrachyura section. Morphological and molecular analyses do not reveal a monophyletic Podotremata, but rather that it is paraphyletic, and so the most recent classifications divide "Podotremata" into three sections: Dromiacea, Cyclodorippoidea and Raninoida.

<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">Polychelida</span> Infraorder of crustaceans

Polychelida is an infraorder of decapod crustaceans. Fossil representatives are known dating from as far back as the Upper Triassic. A total of 38 extant species, all in the family Polychelidae, and 55 fossil species have been described.

<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.

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

Gebiidea is an infraorder of decapod crustaceans. Gebiidea and Axiidea are divergent infraoders of the former infraorder Thalassinidea. These infraorders have converged ecologically and morphologically as burrowing forms. Based on molecular evidence as of 2009, it is now widely believed that these two infraorders represent two distinct lineages separate from one another. Since this is a recent change, much of the literature and research surrounding these infraorders still refers to the Axiidea and Gebiidea in combination as "thalassinidean" for the sake of clarity and reference. This division based on molecular evidence is consistent with the groupings proposed by Robert Gurney in 1938 based on larval developmental stages.

<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:

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. 1 2 3 Ling Ming Tsang; Christoph D. Schubart; Shane T. Ahyong; Joelle C.Y. Lai; Eugene Y.C. Au; Tin-Yam Chan; Peter K.L. Ng; Ka Hou Chu (2014). "Evolutionary History of True Crabs (Crustacea: Decapoda: Brachyura) and the Origin of Freshwater Crabs". Molecular Biology and Evolution . 31 (5). Oxford University Press : 1173–1187. doi: 10.1093/molbev/msu068 .
  3. 1 2 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.