Middle snails

from Wikipedia, the free encyclopedia

The division of living beings into systematics is a continuous subject of research. Different systematic classifications exist side by side and one after the other. The taxon treated here has become obsolete due to new research or is not part of the group systematics presented in the German-language Wikipedia.

The middle snails (Mesogastropoda) are an obsolete taxonomic concept of the snails (Gastropoda). The MESOGASTROPODA made within these obsolete classification an order of class prosobranch (Prosobranchia) is to form one of the largest groups of species within the worm. The variety of forms and the diversity of the populated habitats are correspondingly large. The middle snails are no longer regarded by the phylogenetic system as monophyletic, i.e. descending from a common ancestor.

The designation "middle snails " goes back to Johannes Thiele , who assigned this group within the front gill snails a place between old snails and new snails due to their morphological characteristics . This system was largely accepted in its basic features for many decades and was only revised on a phylogenetic basis in 1997 by Ponder and Lindberg. However, the new system is still being discussed at the moment, so that many institutions fall back on the established system until important questions have been clarified using molecular genetic methods.

Many species of this order can be found on beaches and coasts of the sea, such as the periwinkle , but also snail families living in freshwater such as the pond snails are counted among the middle snails . What these species have in common is that they have a broad rasp tongue that has more than three, usually even seven, teeth per transverse row.

Systematics

Thin-shelled Rissoa ( Rissoa membranous ) - the green stripe is eelgrass ( Zostera marina )

The system is no longer up to date.

literature

  • Johannes Thiele: Handbook of Systematic Molluscology. 2 volumes, 1154 pages, 584 illustrations, 1929–1935.
  • Ponder & Lindberg: Towards a phylogeny of gastropod molluscs; an analysis using morphological characters. In: Zoological Journal of the Linnean Society. 119, 1997, pp. 83-2651.