Point snails

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Point snails
Point snail (Punctum pygmaeum)

Point screw ( Punctum pygmaeum )

Systematics
Subclass : Orthogastropoda
Superordinate : Heterobranchia
Order : Lung snails (pulmonata)
Subordination : Land snails (Stylommatophora)
Superfamily : Punctoidea
Family : Point snails
Scientific name
Punctidae
Morse , 1864

The point snails (Punctidae) are a family from the subordination of the land snails (Stylommatophora). They are mostly very small snails; the point snail ( Punctum pygmaeum ) is the smallest snail in Europe with a maximum shell diameter of 1.6 mm.

features

The right-hand wound housings have wide bifurcations, strongly flattened and have about 3.5 to 4 turns. They are small to very small and only measure a few millimeters in diameter. The navel is large, flat and open, the whorls are rounded. The mouth is usually round, egg-shaped or slightly indented by the spindle. The edge of the mouth is usually simple, often turned over in the navel area. However, some taxa may have reinforcements in the estuary.

The shell is thin. The housings are mostly yellowish-brownish to reddish-brown. The surface is provided with growth strips that can be reinforced almost like ribs.

In the male part of the genital apparatus, the epiphallus is rudimentary or completely reduced. The inner wall of the penis has a longitudinal pillar structure. The penile retractor attaches to the apical part of the penis or the epiphallus if it is still present. The egg ladder (spermoviduct) is very large. The free fallopian tube is short; the vagina is a little longer. The base of the stem of the spermathec is thickened. The reservoir of the spermatheque is embedded in the base of the moderately large albumin gland. The atrium is relatively long.

Geographical distribution, occurrence and way of life

The family is spread around the world. The animals live in the foliage layer of forests. They feed on rotting plant material.

Taxonomy

The taxon was established in 1864 by Edward Sylvester Morse . The family of point snails is the nominate family of the superfamily Punctoidea, which also includes the families Charopidae Hutton, 1884, Cystopeltidae Cockerell, 1891, bowl snails (Patulidae = Discidae Thiele, 1931), Endodontidae Pilsbry, 1895, Helicodiscidae Pilsbrysbrysbrysbry , 1939 , Oreohelicidae Pilsbrysbrysbry , 1939 , Thyrophorellidae Girard, 1895 and the extinct family Anastomopsidae Nordsieck, 1986. Schileyko counts the Helicodiscidae as a subfamily of the Punctidae. The Punctidae family is divided into two subfamilies Laominae Suter, 1913 and Punctinae Morse, 1864.

literature

  • Philippe Bouchet & Jean-Pierre Rocroi: Part 2. Working classification of the Gastropoda . Malacologia, 47: 239-283, Ann Arbor 2005 ISSN  0076-2997
  • Michael P. Kerney, RAD Cameron & Jürgen H. Jungbluth: The land snails of Northern and Central Europe. 384 pp., Paul Parey, Hamburg & Berlin 1983, ISBN 3-490-17918-8
  • Christopher M. Wade, Peter B. Mordan, and Fred Naggs: Evolutionary relationships among the Pulmonate land snails and slugs (Pulmonata, Stylommatophora). Biological Journal of the Linnean Society, 87: 593-610, Oxford 2006 ISSN  0024-4066

Individual evidence

  1. Anatolij A. Schileyko: Treatise on recent terrestrial pulmonate molluscs. Part 8. Punctidae, Helicodiscidae, Discidae, Cystopeltidae, Euconulidae, Trochomorphidae. Ruthenica, Supplement, 2 (8): 1035-1166, Moscow 2002 ISSN  0136-0027
  2. ^ Edward Sylvester Morse: Observations on the terrestrial Pulmonifera of Maine, including a catalog of all the species of terrestrial and fluviatil Mollusca known to inhabit the state. Journal of the Portland Society of Natural History, 1 (1): 1-63, 1864 [online at Biodiversity Heritage Library], pp. 5, 27 (as Punctinae).
  3. MolluscaBase: Punctidae Morse, 1864
  4. Patricio Vargas-Almonacid and José R. Stuardo: Dos géneros nuevos de caracoles terrestres (Stylommatophora: Arionacea) de Chile. Revista de Biología Tropical (International Journal of Tropical Biology) 55 (2): 693-708, 2007 ISSN  0034-7744 abstract