Arcida

{{Short description|Order of molluscs}} {{Automatic taxobox | fossil_range = {{Fossil range|Lower Ordovician|Recent}} | image = AnadaraPliocene.jpg | image_caption = ''Anadara'' from the Pliocene of Cyprus. | taxon = Arcida | subdivision_ranks = Families | subdivision = 11, See text. | synonyms = Arcoida }}

The '''Arcida''' is an extant order of bivalve molluscs.<ref name="WoRMS_207" /> This order dates back to the lower Ordovician period. They are distinguished from related groups, such as the mussels, by having a straight hinge to the shells, and the adductor muscles being of equal size.<ref name=IZ>{{cite book |author= Barnes, Robert D. |year=1982 |title= Invertebrate Zoology |publisher= Holt-Saunders International |location= Philadelphia, PA|page= 430|isbn= 978-0-03-056747-6}}</ref> The duplivincular ligament, taxodont dentition, and a shell microstructure consisting of the outer crossed lamellar and inner complex crossed lamellar layers are defining characters of this order.<ref>{{Cite journal | doi = 10.1016/S1055-7903(03)00013-7| pmid = 12742748| title = Phylogenetic analysis of the subclass Pteriomorphia (Bivalvia) from mtDNA COI sequences| journal = Molecular Phylogenetics and Evolution| volume = 27| issue = 3| pages = 429–440| year = 2003| last1 = Matsumoto | first1 = M. }}</ref>

Seven families are currently recognised within the order, including the well-known ark clams or ark shells in the family Arcidae.

==Taxonomy== The order Arcida, as the suborder Arcacea, is included in the order Taxodonta by R.C. Moore, 1952,<ref>R.C, Moore, Pelecypods, Ch 10, Inverrtebrate Fossils, Moore, Lalicker, and Fischer. McGraw-Hill, 1952.</ref> characterised by simple hinge-line dentition consisting of small, numerous, similar hinge teeth, separate mantle lobes, poorly developed siphons, and filibranch gills.

In 2010, Bieler, Carter & Coan<ref name=Nomenclator /> proposed a new classification system for the Bivalvia which combines the taxodont Arcida with the dysodont Limida Mytilida, Ostreida and Pteriida as the Pteriomorphia. Subtaxa included in the Arcida are shown below.

In 2016, the superfamilies of Arcida changed from two to three, with an additional superfamily of fossils only. The new taxonomy is as follows:<ref name="WoRMS_207" /><ref name=Nomenclator /> *Superfamily Arcoidea Lamarck, 1809<ref name="WoRMS_489054" /> **Family Arcidae Lamarck, 1809 **Family {{†}}Catamarcaiidae Cope, 2000 **Family Cucullaeidae Stewart, 1930 **Family {{†}}Frejidae Ratter & Cope, 1998 **Family Glycymerididae Dall, 1908 (1847) **Family Noetiidae Stewart, 1930 **Family Parallelodontidae Dall, 1898 *Superfamily Glyptarcoidea Cope, 1996{{†}}:<ref name=Lemer2016 /><ref name="WoRMS_833107" /><ref name="Cope 1996" /> with fossil species only. **Family Glyptarcidae Cope, 1996{{†}} **Family Pucamyidae Sánchez & Benedetto, 2007{{†}} *Superfamily Limopsoidea Dall, 1895<ref name="WoRMS_489059" /> **Family Limopsidae Dall, 1895 **Family Philobryidae F. Bernard, 1897

==References== {{Reflist |refs= <ref name="Cope 1996">{{cite journal |last=Cope |first=J. C. W. |year=1996 |title=Early Ordovician (Arenig) bivalves from the Llangynog inlier, South Wales |journal=Palaeontology |volume=39 |issue=4 |pages=979–1025, pl. 1–7 |language=en }}</ref> <ref name=Lemer2016>{{cite journal |last1=Lemer |first1=S. |last2=González |first2=V.L. |last3=Bieler |first3=R. |last4=Giribet |first4=G. |year=2016 |title=Cementing mussels to oysters in the pteriomorphian tree: a phylogenomic approach |journal=Proceedings of the Royal Society B: Biological Sciences |volume=283 |article-number=20160857 |language=en |doi=10.1098/rspb.2016.0857|pmid=27358369 |pmc=4936043}}</ref> <ref name=Nomenclator>{{cite journal |last1=Bieler |first1=R. |last2=Carter |first2=J.G. |last3=Coan |first3=E.V. |year=2010 |title=Classification of Bivalve families |pages=113–133 |journal=Malacologia |volume=52 |issue=2 |doi=10.4002/040.052.0201 |url=https://www.biodiversitylibrary.org/page/63543089#page/345/mode/1up |s2cid=86546840 |language=en }}</ref> <ref name="WoRMS_207">{{cite WoRMS |id=207 |db=MolluscaBase |author-link=WoRMS |last2=Gofas |first2=Serge |last1=Bieler |first1=Rüdiger |title=Arcoida Stoliczka, 1871 |date=2016-02-07 |access-date=2017-01-15 }}</ref> <ref name="WoRMS_489059">{{cite WoRMS |id=489059 |db=MolluscaBase |author-link=WoRMS |last=Gofas |first=Serge |date=2010-07-09 |access-date=2017-01-15 |title=Limopsoidea Dall, 1895 }}</ref> <ref name="WoRMS_489054">{{cite WoRMS |id=489054 |db=MolluscaBase |author-link=WoRMS |last=Gofas |first=Serge |date=2010-07-09 |access-date=2017-01-15 |title=Arcoidea Lamarck, 1809 }}</ref> <ref name="WoRMS_833107">{{cite WoRMS |id=833107 |db=MolluscaBase |author-link=WoRMS |last=Decock |first=Wim |date=2015-01-29 |access-date=2017-01-15 |title=Glyptarcoidea Cope, 1996 }}</ref> }}

Category:Arcida Category:Bivalve orders