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Comprehensive Description

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The Scalidophora is a clade that includes the traditional phyla Priapula, Kinorhyncha, and Loricifera. This grouping has been recovered as monophyletic in a diversity of studies (Halanych 2004). Nielsen (2001) used the name Cephalorhyncha for this clade, but (as Nielsen himself noted) this name has been used previously for a clade that also included the Nematomorpha. Based on new molecular data and analyses, Sørensen et al. (2008) concluded that the Loricifera and Nematomorpha appear to be sister taxa, which would make the Scalidophora (or Cephalorhyncha sensu Nielsen 2001) clade paraphyletic. As of 2010, relationships among phyla within the Ecdysozoa remain poorly resolved, so it is difficult to know which groups will eventually win wide acceptance by specialists as convincingly monophyletic and deserving of a name.

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Scalidophora

provided by wikipedia EN
"Cephalorhyncha" redirects here. For the kinorhynch genus, see Cephalorhyncha (genus).

Scalidophora is a group of marine pseudocoelomate protostomes that was proposed on morphological grounds to unite three phyla: the Kinorhyncha, the Priapulida and the Loricifera.[2][3] The three phyla have four characters in common — chitinous cuticle that is moulted, rings of scalids on the introvert, flosculi, and two rings of introvert retracts.[4] However, the monophyly of the Scalidophora is not supported by molecular studies, where the position of the Loricifera was uncertain[2] or as sister to the Panarthropoda.[3] Both studies supported a reduced Scalidophora comprising the Kinorhyncha and Priapulida as sister phyla. Their closest relatives are the Panarthropoda, Nematoda and Nematomorpha; thus they are placed in the group Ecdysozoa.

The two species in the genus Markuelia, known from fossilized embryos from the middle Cambrian, are thought to be stem Scalidophorans.

The group has also been considered a single group, Cephalorhyncha,[5] with three classes.

The group is named after the spines (scalids) covering the introvert (head that can be retracted into the trunk).[6]

References

  1. ^ Harvey, T. H.; Dong, X.; Donoghue, P. C. (March–April 2010). "Are palaeoscolecids ancestral ecdysozoans?". Evolution & Development. 12 (2): 177–200. doi:10.1111/j.1525-142X.2010.00403.x. PMID 20433458..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"""""'"'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
  2. ^ a b Telford, M. J.; Bourlat, S. J.; Economou, A.; Papillon, D.; Rota-Stabelli, O. (27 April 2008). "The evolution of the Ecdysozoa" (pdf). Philosophical Transactions of the Royal Society B. 363 (1496): 1529–1537. doi:10.1098/rstb.2007.2243. PMC 2614232. PMID 18192181.
  3. ^ a b Yamasaki, Hiroshi; Fujimoto, Shinta; Miyazaki, Katsumi (2015-06-30). "Phylogenetic position of Loricifera inferred from nearly complete 18S and 28S rRNA gene sequences". Zoological Letters. 1: 18. doi:10.1186/s40851-015-0017-0. ISSN 2056-306X.
  4. ^ Heiner, I., Kristensen, R.H. 2005. Two new species of the genus Pliciloricus (Loricifera, Pliciloricidae) from the Faroe Bank, North Atlantic. Zoologischer Anzeiger. 243: 121–138.
  5. ^ Dirnberger, J. "Explanations and Difficulties in Invertebrate Phylogeny". Invertebrate Zoology. Kennesaw State University. Retrieved 2012-08-11.
  6. ^ Dunn, C. W.; Hejnol, A.; Matus, D. Q.; Pang, K.; Browne, W. E.; Smith, S. A.; Seaver, E.; Rouse, G. W.; Obst, M.; et al. (10 April 2008). "Broad Phylogenomic Sampling Improves Resolution of the Animal Tree of Life". Nature. 452 (7188): 745–749. doi:10.1038/nature06614. PMID 18322464.
Extant Animal phyla
Animalia Diploblasts
(Eumetazoa) ParaHoxozoa Planulozoa Bilateria
(Triploblasts) Nephrozoa
  • (see below↓)
Deuterostomia Ambulacraria ProtostomiaEcdysozoaScalidophoraN+L+PNematoidaL+P Panarthropoda Tactopoda SpiraliaGnathifera¹M+S PlatytrochozoaR+MMesozoa Rouphozoa¹ LophotrochozoaM+K Kryptotrochozoa LophophorataBryozoa s.l. Brachiozoa

Major groups
within phyla
Phyla with ≥1000 extant species bolded
See also
Diploblasts


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Scalidophora: Brief Summary

provided by wikipedia EN
"Cephalorhyncha" redirects here. For the kinorhynch genus, see Cephalorhyncha (genus).

Scalidophora is a group of marine pseudocoelomate protostomes that was proposed on morphological grounds to unite three phyla: the Kinorhyncha, the Priapulida and the Loricifera. The three phyla have four characters in common — chitinous cuticle that is moulted, rings of scalids on the introvert, flosculi, and two rings of introvert retracts. However, the monophyly of the Scalidophora is not supported by molecular studies, where the position of the Loricifera was uncertain or as sister to the Panarthropoda. Both studies supported a reduced Scalidophora comprising the Kinorhyncha and Priapulida as sister phyla. Their closest relatives are the Panarthropoda, Nematoda and Nematomorpha; thus they are placed in the group Ecdysozoa.

The two species in the genus Markuelia, known from fossilized embryos from the middle Cambrian, are thought to be stem Scalidophorans.

The group has also been considered a single group, Cephalorhyncha, with three classes.

The group is named after the spines (scalids) covering the introvert (head that can be retracted into the trunk).

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wikipedia EN