Lophotrochozoa

Lophotrochozoa Temporal range: 536–0 Ma[1] PreЄ Є O S D C P T J K Pg N
Caribbean reef squid or Sepioteuthis sepioidea is a complex lophotrochozoan.
Scientific classification
Kingdom:	Animalia
Subkingdom:	Eumetazoa
Clade:	Bilateria
Clade:	Nephrozoa
(unranked):	Protostomia
(unranked):	Spiralia
Superphylum:	Lophotrochozoa Halanych et al., 1995
Phyla
Annelida Brachiopoda Bryozoa Dicyemida Entoprocta Hyolitha † Mollusca Nemertea Phoronida

Lophotrochozoa (/ləˌfɒtroʊkoʊˈzoʊə/, "crest/wheel animals") is a clade of protostome animals. The taxon was established as a monophyletic group based on molecular evidence.^[2][3]

Terminology

The word "lophotrochozoan" is sometimes equated with spiralian.^[4] When used in a broader sense (sensu lato), it can include rotifers and platyhelminthes.^[5] When used sensu stricto, it refers to a subgroup of Spiralia.

Groups

The Lophotrochozoa comprise two groups (which are not necessarily monophyletic), the trochozoans and the lophophorata. The exact relationships between the different phyla are not entirely certain.

• Trochozoans produce trochophore larvae, which have two bands of cilia around their middle.^[6] Previously these were treated together as the Trochozoa, together with the arthropods, which do not produce trochophore larvae but were considered close relatives of the annelids because they are both segmented. However, they show a number of important differences, and the arthropods are now placed separately among the Ecdysozoa. The Trochozoa include the Nemertea, Mollusca, Sipuncula, and Annelida.^[6]
• The Lophophorata are united by the presence of a lophophore, a fan of ciliated tentacles surrounding the mouth, and so were treated together as the lophophorates. They are unusual in showing radial cleavage, and some authors considered them deuterostomes. The ‘clade’ Lophotrochozoa was founded on evidence from 18S ribosomal RNA,^[2] but a later study on LSU and SSU ribosomal genes suggested that the Lophophorata is polyphyletic.^[7]

Other phyla are included on the basis of molecular data.

With the introduction of Platytrochozoa and Rouphozoa, one candidate phylogeny is pictured below – though other studies recover a range of different alternative possibilities:^{[8][9][10][11]}

A number of fossil taxa can be identified as early Lophotrochozoans, even if their precise affinity remains contested: see Debate about Cambrian lophotrochozoans.

References

Further reading

Wikispecies has information related to: Lophotrochozoa

• Podsiadlowski, R (2009). "Phylogeny and mitochondrial gene order variation in Lophotrochozoa in the light of new mitogenomic data from Nemertea". BMC Genomics. 10: 364. doi:10.1186/1471-2164-10-364.