Head shield snails

Head shield snails
Some representative cephalaspidea
Systematics
Trunk : Molluscs (mollusca) Class : Snails (gastropoda) Subclass : Orthogastropoda Superordinate : Heterobranchia Order : Hind gill snails (Opisthobranchia) Subordination : Head shield snails
Scientific name
Cephalaspidea
PH Fischer , 1883

The headshell snails (Cephalaspidea) are a subordinate of the hind gill snails . The suborder includes around 7000 species of marine nudibranchs.

The name headshield snail refers to a headshield that is detached from the back and corresponds to widened antennae.

features

Apart from the head shield, these snails are characterized by the fact that they usually have a shell, they have no tentacles and that lateral enlargements (parapodia) occur. With the exception of a few freshwater species, almost all head shield snails occur exclusively in the sea.

Tribal history

The head shield snails are a very basal group of the Euthyneura (straight-nerved) . There are close relationships with the Streptoneura , as many of the original features ( autamorphisms of the Gastropoda ) are often still present.

Such characteristics would be:

• Operculum ( Acteon only )
• Crossing of the pleuroviscal connective, no concentration of the ganglia
• Atrium in front of the heart (ventricle)

Systematics

The taxonomy of snails is subject to revision and change. Therefore there are different classifications. The one that goes back to Johannes Thiele (1929–1935) is usually regarded as classic . It was recognized until the 1990s. A more modern and the last one established on the basis of purely morphological approaches is that of Ponder & Lindberg (1997). The current system is phylogenetically oriented and goes back to Bouchet & Rocroi (2005).

Systematics according to Ponder & Lindberg (1997)

• Great gastropoda
  • Subclass Orthogastropoda WF Ponder & DR Lindberg, 1995
    • Subclass Apogastropoda L. Salvini-Plawen & G. Haszprunar, 1987
      • Superorder Heterobranchia JE Gray, 1840
        • Euthyneura group
          • Order Opisthobranchia A. Milne-Edwards, 1848
            • Suborder Cephalaspidea PH Fischer, 1883
              • Superfamily Acteonoidea A. d'Orbigny, 1835
              • Superfamily Bulloidea J.-P. Lamarck, 1801
              • Superfamily Diaphanoidea NH Odhner, 1914
              • Superfamily Haminoeoidea HA Pilsbry, 1895
              • Superfamily Philinoidea JE Gray, 1850
              • Superfamily Ringiculoidea RA Philippi, 1853
              • Superfamily Cylindrobulloidea J. Thiele, 1931

Systematics according to Bouchet & Rocroi (2005)

• Great gastropoda
  • Clade Heterobranchia JE Gray, 1840
    • informal group Opisthobranchia A. Milne-Edwards, 1848
      • Clade Cephalaspidea PH Fischer, 1883
        • Superfamily Bulloidea J.-P. Lamarck, 1801
          • Family Bullidae J.-P. Lamarck, 1801
        • Superfamily Diaphanoidea JE Gray, 1840
          • Family Diaphanidae NH Odhner, 1914
          • Family Notodiaphanidae J. Thiele, 1931
        • Superfamily Haminoeoidea HA Pilsbry, 1895
          • Family Haminoeidae
          • Family Bullactidae J. Thiele, 1926
          • Family Smaragdinellidae J. Thiele, 1925
        • Superfamily Philinoidea JE Gray, 1850
          • Family Aglajidae HA Pilsbry, 1895
          • Family Cylichnidae A. Adams, 1850
          • Family Gastropteridae WJ Swainson, 1840
          • Family Philinidae JE Gray, 1850
          • Family Philinoglossidae Hertling, 1932
          • Family Plusculidae Franc, 1968
          • Family Retusidae J. Thiele, 1926
        • Superfamily Runcinoidea
          • Family Runcinidae H. Adams & A. Adams, 1854
          • Family Ilbiidae Burn, 1963

In this system, in comparison with the preceding system by Ponder & Lindberg (1997)

• After A. d'Orbigny (1835) the superfamily Acteonoidea moved as a superfamily to the informal group Lower Heterobranchia ( Clade Heterobranchia ),
• the superfamily Cylindrobulloidea after J. Thiele (1931) a family of the new group Cylindrobullida ( informal group Opisthobranchia ).

I.e. the clade Cephalaspidea has been reduced in size compared to the suborder Cephalaspidea.

literature

• A. Kästner: Textbook of special zoology . Volume I, Part 3; Jena 1993, ISBN 3-334-60412-8

Web links

Commons : Shield snails  - Collection of images, videos and audio files

• Weichtiere.at: Headshell snails (Cephalaspidea)
• http://sn2000.taxonomy.nl Taxonomy
• www.marinespecies.org - taxonomy, literature references
• www.seaslug.com - further links: taxonomy, images, etc.
• www.seaslugforum.net - Sea Slug Forum: Technical discussions, pictures

Individual evidence

1. ^ Ponder, WF & Lindberg, DR : "Towards a phylogeny of gastropod molluscs: an analysis using morphological characters" ; In: Zoological Journal of the Linnean Society , Volume 119, No. 2, pp. 83-265; 1997; doi : 10.1111 / j.1096-3642.1997.tb00137.x
2. ↑ Bouchet, P. & Rocroi, J.-P .: Part 2. "Working classification of the Gastropoda" ; In: Malacologia Volume 47, pp. 239-283, Ann Arbor 2005; ISSN  0076-2997
3. ↑ Bouchet, P. & Rocroi, J.-P. (Eds.): Frýda, J., Hausdorf, B. Ponder, WF Valdés, Á. & Warén, A .: "Classification and nomenclator of gastropod families" ; In: Malacologia: International Journal of Malacology Volume 47, Nos. 1-2; ConchBooks, Hackenheim 2005; ISBN 3-925919-72-4 , ISSN  0076-2997 ; http://www.vliz.be/Vmdcdata/imis2/ref.php?refid=78278
4. ↑ Poppe, GT & Tagoro, SP: 23 February 2006 "The New Classification of Gastropods gemäß to Bouchet & Rocroi, 2005" ; PDF ( Memento of the original from September 27, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.