Acanthinula

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Acanthinula
Spiny litter snail (Acanthinula aculeata, OF Müller, 1774)

Spiny litter snail ( Acanthinula aculeata , OF Müller, 1774)

Systematics
Order : Lung snails (pulmonata)
Subordination : Land snails (Stylommatophora)
Superfamily : Pupilloidea
Family : Grass snails (Valloniidae)
Subfamily : Acanthinulinae
Genre : Acanthinula
Scientific name
Acanthinula
Beck , 1847

Acanthinula is a genus of land-living snails from the family of grass snails (Valloniidae); the family belongs to the land snails (Stylommatophora). The oldest species come from the Paleocene .

features

The conical-spherical housings are 1.7 to 2.1 mm high and 2 to 2.3 mm wide. They have up to four moderately curved turns, which are separated from each other by shallow seams. The turns increase regularly, the last turn does not decrease. The base is flattened slightly angular. The embryonic casing has clear spiral lines on the surface. The postembryonic convolutions have lamellar ribs made of periostracum , which are drawn out on the periphery to triangular extensions. There are also occasional indistinct spiral lines. The mouth is egg-shaped, wider than it is high and is oblique to the axis of the housing. The mouth edge is only turned over in the spindle area and at the base, initially strongly (at the spindle) then mostly tapering towards the base. The rest of the mouth edge is only very slightly turned over and only slightly thickened on the inside. The umbilicus is open and cylindrical. The housings are horn-colored to dark brown.

The species of the genus Acanthinula are often aphallic, i. H. the male ducts in the hermaphroditic genital apparatus are reduced. However, there are also euphallic specimens in which the male tract has been preserved. The protein gland (albumin gland) is very large, and the egg duct is very long and distended. The vas deferens is unusually short and straight. It opens quickly into a short, spindle-shaped epiphallus. Two short, fork-shaped blind processes are formed at the epiphallus / penis transition. The penis is cylindrical and comparatively long. In the last quarter of the penis there is another, very long, club-shaped appendix. The retractor muscle forks before insertion onto the penis. One branch attaches to one of the two processes at the epiphallus / penis transition, the second strand to the lower, very thick part of the long penile appendix. The free fallopian tube is only very short, as the spermathec begins shortly after the spermatic duct branches off. The vagina is moderately long and thick. The stem of the spermathec is thin and moderately long, the bladder small and elongated-ovoid.

Geographical distribution

The genus Acanthinula is common in Europe, Asia Minor and the Caucasus. It is also found in the Canary Islands and the Azores, as well as in North and East Africa. The species has now been introduced to other parts of the world.

Taxonomy

The taxon was established in 1847 by Henrik Henriksen Beck as a subgenus of Helix Linné in 1757. He added two species to his new subgenus: Acanthinula aculeata (Müller, 1774) and Acanthinula lamellata (Jeffreys, 1830). The type species is Helix aculeata Müller, 1774 by later definition by Albers & Martens (1860: XIII, 100). The latter species is the type species from Spermodea Westerlund, 1902, a generally recognized genus.

The scope of the genre is, however, very uncertain, as no monograph has been published so far. Most of the fossil forms are poorly known. Acanthinula Beck, 1847 is the type genus of the subfamily Acanthinulinae Steenberg, 1917.

supporting documents

literature

  • József Kókay: Nonmarine mollusc fauna from the Lower and Middle Miocene, Bakony Mts, W Hungary. Geologica Hungarica, Series Palaeontologica, 56: 1–196, 2006 PDF
  • Josef Paul Lueger: The land snails in the Pannon and Pont of the Vienna basin. 124 p., Commissioned by Springer-Verlag, Vienna, New York, 1981.
  • Anatolij A. Schileyko: Treatise on Recent terrestrial pulmonate molluscs, Part 1. Achatinellidae, Amastridae, Orculidae, Strobilopsidae, Spelaeodiscidae, Valloniidae, Cochlicopidae, Pupillidae, Chondrinidae, Pyramidulidae . Ruthenica, Supplement 2 (1): 1-126, Moscow 1998 ISSN  0136-0027
  • Wilhelm Wenz: Gastropoda extramarina tertiaria. In: Carl Diener (Ed.), Fossilium catalogus, 1 Animalium , 20: 737-1068, Berlin 1923 Online at www.biodiversitylibrary.org (pp. 968-979).

Individual evidence

  1. ↑ Hartmut Nordsieck (V.2014): Annotated check-list of the genera of fossil land snails (Stylommatophora) of western and central Europe (Cretaceous - Pliocene) ( Memento from July 14, 2014 in the Internet Archive )
  2. ↑ Henrik Henriksen Beck: "Directory of a collection of land conchylies from the Danish states in Europe, consisting of 2,058 individuals, representing 158 species belonging to 44 sexes, sent as a result of the highest order to the meeting of German naturalists and doctors in Kiel in 1846 the Royal Particular Zoological Museum ". Official report on the Assembly of German Natural Scientists and Doctors, 24: 122-124, Kiel 1847 Digitized copy on AnimalBase .
  3. ↑ Johann Christoph Albers (malacologist), Eduard von Martens: The Heliceen systematically arranged according to natural relationship by Joh. Christian Albers. Second edition based on the manuscript that was left behind, obtained from Eduard von Martens. S. I-XVIII, 1-359, Engelmann, Leipzig 1860.

Web links

Commons : Acanthinula  - collection of images, videos and audio files