Cephalaspidea

Some representative Cephalaspidea

The head shield screws ( Cephalaspidea ) are a suborder of the opisthobranch. The submission includes about 7000 species of marine snails.

The name of head shield worm refers to an offset from the back of head shield, which widened sensors corresponds.

Features

Apart from the head shield this worm is distinguished further that mostly a shell is present, they do not have tentacles and that lateral extensions ( parapodia ) occur. Apart from a few freshwater species, almost all head shield snails occur exclusively in the sea.

Phylogeny

The head shield snails are a very basal group of Euthyneura ( Geradnervige ). There are close relations with the Streptoneura, since many of the original features ( Autamorphien the Gastropoda ) are often still present. Such features would be:

  • Operculum (only Acteon )
  • Crossing of the Pleurovisceralkonnektive, no concentration of ganglion
  • Atrium in front of the heart ( ventricles)

System

The taxonomy of the worm is subject to revision and change. Therefore, there are different classifications. On Johannes Thiele (1929-1935) is usually considered going back as classical. She was recognized until the 1990s. A more modern and the last established on purely morphological approaches to systematics is that of Ponder & Lindberg (1997). The current system is phylogenetically oriented and goes back to Bouchet & Rocroi ( 2005).

Classification by Ponder & Lindberg (1997)

  • Class Gastropoda Subclass Orthogastropoda W. F. Ponder & D. R. Lindberg, 1995 Subclass Apogastropoda L. Salvini - Plawen & G. Haszprunar, 1987 Superorder Heterobranchia J. E. Gray, 1840 group Euthyneura Order Opisthobranchia A. Milne Edwards 1848 Subordination Cephalaspidea P.H. Fischer 1883 Superfamily Acteonoidea A. d' Orbigny, 1835
  • Superfamily Bulloidea J.-P. Lamarck, 1801
  • Superfamily Diaphanoidea N.H. Odhner, 1914
  • Superfamily Haminoeoidea H. A. Pilsbry, 1895
  • Superfamily Philinoidea J. E. Gray, 1850
  • Superfamily Ringiculoidea R. A. Philippi, 1853
  • Superfamily Cylindrobulloidea J. Thiele, 1931

Bouchet & Rocroi classification by (2005)

  • Class Gastropoda Clade Heterobranchia J. E. Gray, 1840 informal group Opisthobranchia A. Milne -Edwards, 1848 Clade Cephalaspidea P.H. Fischer, 1883 Superfamily Bulloidea J.-P. Lamarck, 1801 Family Bullidae J.-P. Lamarck, 1801
  • Family Diaphanidae N.H. Odhner, 1914
  • Family Notodiaphanidae J. Thiele, 1931
  • Family Haminoeidae
  • Family Bullactidae J. Thiele, 1926
  • Family Smaragdinellidae J. Thiele, 1925
  • Family Aglajidae H. A. Pilsbry, 1895
  • Family Cylichnidae A. Adams, 1850
  • Family Gastropteridae W.J.Swainson, 1840
  • Family Philinidae J. E. Gray, 1850
  • Family Philinoglossidae Hertling, 1932
  • Family Plusculidae Franc, 1968
  • Family Retusidae J. Thiele, 1926
  • Family Runcinidae H. Adams & A.Adams, 1854
  • Family Ilbiidae Burn, 1963

In this system, in comparison with the previous system of Ponder & Lindberg (1997)

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

That the clade Cephalaspidea was reduced in relation to the subordination Cephalaspidea.

Autapomorphy Operculum (gastropod) Winston Ponder David R. Lindberg Digital Object Identifier
172744
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