dcsimg
Image of Cratena Bergh 1864
Creatures » » Animals » » Molluscs » Snails

Heterobranchia Burmeister 1837

Heterobranchia

provided by wikipedia EN

Heterobranchia, the heterobranchs (meaning "different-gilled snails"), is a taxonomic clade of snails and slugs, which includes marine, aquatic and terrestrial gastropod mollusks.

Heterobranchia is one of the main clades of gastropods. Currently Heterobranchia comprises three informal groups: the lower heterobranchs, the opisthobranchs and the pulmonates.[2]

 src=
A shell of the marine species Bulla quoyii, which is an opisthobranch.

Diversity

The three subdivisions of this large clade are quite diverse:

  • The Lower Heterobranchia includes shelled marine and freshwater species.
  • Opisthobranchia are almost all marine species, some shelled and some not. The internal organs of the opisthobranchs have undergone detorsion (unwinding of the viscera that were twisted during torsion).
  • The Pulmonata includes the majority of land snails and slugs, many freshwater snails, and a small number of marine species. The mantle cavity of the Pulmonata is modified into an air-breathing organ. They are also characterized by detorsion and a symmetrically-arranged nervous system. The pulmonates almost always lack an operculum and are hermaphroditic.

Taxonomy

Older taxonomy

The families currently included in Heterobranchia have historically been placed in many different parts of the taxonomic class of gastropods. Earlier authors (such as J.E. Gray, 1840) considered Heterobranchia to consist of only marine gastropods, and conceptualized it as a borderline category, intermediate between the Opisthobranchia & Pulmonata, and all the other gastropods.[3]

The (sometimes recognized) category Heterostropha within the Heterobranchia, which includes such families as Architectonicidae, the sundial or staircase snails, is primarily characterized by a shell which has a heterostrophic protoconch, in other words the apical whorls are coiled in the opposite plane to the adult whorls. The classification of this group was revised by Ponder & Warén in 1988.[4]

According to the older taxonomy of the Gastropoda (Ponder & Lindberg, 1997) the Heterobranchia were ranked as a superorder.

2005 taxonomy

 src=
The graph of neighbor-joining phylogenetic tree shows that there is no clade-supporting pattern for the monophyly of Opisthobranchia (green) or of Pulmonata (yellow) based on datasets by Jörger et al. (2010).[5]

Heterobranchia is currently one of the main clades of gastropods. For a detailed taxonomy, see Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)#Clade Heterobranchia.

2010 taxonomy

Jörger et al. (2010)[5] have redefined major groups within the Heterobranchia: they created the new clades Euopisthobranchia and Panpulmonata.[5]

A cladogram showing phylogenic relations of Heterobranchia as proposed by Jörger et al. (2010):[5]

Heterobranchia  

Valvatoidea

     

Orbitestelloidea

     

Cimoidea

       

Rissooidea

   

Acteonoidea

    Euthyneura Nudipleura

Pleurobranchomorpha

   

Nudibranchia

      Euopisthobranchia

Umbraculoidea

       

Runcinacea

     

Anaspidea

   

Pteropoda

       

Cephalaspidea s.s.

      Panpulmonata    

Siphonarioidea

   

Sacoglossa

         

Glacidorboidea

     

Amphiboloidea

   

Pyramidelloidea

         

Hygrophila

     

Acochlidiacea

Eupulmonata

Stylommatophora

     

Systellommatophora

     

Ellobioidea

     

Otinoidea

   

Trimusculoidea

                           
Lower Heterobranchia

(not monophyletic in study
by Jörger et al. (2010)[5])

References

  1. ^ "PBDB". Paleobiology Database. Retrieved 2 April 2020.
  2. ^ Bouchet P. & Rocroi J.-P. (Ed.); Frýda J., Hausdorf B., Ponder W., Valdes A. & Warén A. 2005. Classification and nomenclator of gastropod families. Malacologia: International Journal of Malacology, 47(1-2). ConchBooks: Hackenheim, Germany. ISBN 3-925919-72-4. ISSN 0076-2997. 397 pp. http://www.vliz.be/Vmdcdata/imis2/ref.php?refid=78278
  3. ^ Haszprunar G. (1985). "The Heterobranchia ― a new concept of the phylogeny of the higher Gastropoda". Zeitschrift für zoologische Systematik und Evolutionsforschung. 23 (1): 15–37. ISSN 0044-3808.
  4. ^ Ponder, W. F.; Warén, A. (1988). "Classification of the Caenogastropoda and Heterostropha- A list of family-group names and higher taxa". Malacological Review Supplement. 4: 288–317.
  5. ^ a b c d e Jörger K. M.; Stöger I.; Kano Y.; Fukuda H.; Knebelsberger T.; Schrödl M. (2010). "On the origin of Acochlidia and other enigmatic euthyneuran gastropods, with implications for the systematics of Heterobranchia". BMC Evolutionary Biology. 10: 323. doi:10.1186/1471-2148-10-323. PMC 3087543. PMID 20973994.
license
cc-by-sa-3.0
copyright
Wikipedia authors and editors
original
visit source
partner site
wikipedia EN

Heterobranchia: Brief Summary

provided by wikipedia EN

Heterobranchia, the heterobranchs (meaning "different-gilled snails"), is a taxonomic clade of snails and slugs, which includes marine, aquatic and terrestrial gastropod mollusks.

Heterobranchia is one of the main clades of gastropods. Currently Heterobranchia comprises three informal groups: the lower heterobranchs, the opisthobranchs and the pulmonates.

 src= A shell of the marine species Bulla quoyii, which is an opisthobranch.
license
cc-by-sa-3.0
copyright
Wikipedia authors and editors
original
visit source
partner site
wikipedia EN