Pyramidal snails

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Pyramidal snails
Pyramidula rupestris

Pyramidula rupestris

Systematics
Superordinate : Heterobranchia
Order : Lung snails (pulmonata)
Subordination : Land snails (Stylommatophora)
Superfamily : Pupilloidea
Family : Pyramidal snails
Genre : Pyramidal snails
Scientific name of the  family
Pyramidulidae
Kennard & Woodward , 1914
Scientific name of the  genus
Pyramidula
Leopold Fitzinger , 1833

Pyramidula is a genus of snails from the family of pyramid snails (Pyramidulidae); the family belongs to the subordination of land snails (Stylommatophora). Pyramidula is the only genus and thus type genus of the pyramid snailfamily(Pyramidulidae).

features

The mostly very small, right-hand wound housings are (high) conical, pressed conical to almost disc-shaped, with strongly graduated, mostly more or less strongly curved circumferences. This gradation results in a "pyramidal" habit. They measure approximately 2.5 to 3 mm in height and approximately 2.5 to 3 mm in diameter. The housings have 4 to 5.5 whorls in the adult stage. The end turn is even somewhat detached in one species, but usually the end turn is not or only slightly lowered from the turn plane. The whorls increase regularly, with some species the whorls differ from the previous whorls. The periphery can be well rounded or shouldered a little. The rounded to egg-shaped mouth is slightly beveled compared to the plane of the winding. The mouth is simple, without “teeth”, with a sharp, fragile, and usually not turned over, mouth seam. Only in the area of ​​the umbilicus can the mouth seam be slightly turned over in some species. The umbilicus is open and moderately to very wide (in relation to the width of the case).

The teleoconche of the housing are mostly reddish-brown with fine streaks of growth. The embryonic shell (protoconch) is almost smooth.

In the male genital tract, the spermatic duct penetrates apically into the long epiphallus, which is slightly longer than the penis. The spermatic duct is slightly swollen at the point of entry. A bag-like appendix sits roughly in the middle of the length of the penis. The penile retractor muscle attaches roughly in the middle of the epiphallus. In the female part, the free fallopian tube is relatively short, while the vagina is relatively long. The sperm library is usually small and elongated and sits on a short stem. The protein gland is large and horn-shaped.

Geographical distribution and habitat

The distribution area extends from Europe and North Africa, across Asia Minor, the Caucasus, Central Asia to East Asia and Japan. Some species are also likely found on the Indian subcontinent (including Sri Lanka). It is missing in Scandinavia.

The animals live on dry, rocky locations on limestone rocks. They live hidden in the cracks and crevices in the rock and are active in damp weather. They feed on lichens that grow on the rocks.

Way of life

As far as is known, the animals are ovoviviparous . The few large eggs are retained in the mantle cavity until the young animals hatch. The animals hatch out of the mantle cavity as ready-made miniature adults.

Taxonomy

Pyramidula was proposed by Leopold Fitzinger in 1833 and received general approval. Type species is Pyramidula rupestris by monotype . It is the only genus of the family Pyramidulidae Kennard & Woodward, 1914. In a later work Kennard and Woodward moved their family back in and placed the genus Pyramidula in the family Pupillidae. Schileyko introduced the Pleurodiscidae Wenz, 1923 as a subfamily to the family Pyramidulidae; the Pyramidulidae would no longer be monotypical. However, other authors did not follow this suggestion. Pyramidula is currently (2018) the only genus of the family Pyramidulidae Kennard & Woodward, 1914.

The species Pyramidula shimekii Pilsbry, 1890 often found in older literature , is now part of the genus Discus .

Individual evidence

  1. ^ Leopold I. Fitzinger: Systematic directory of the molluscs occurring in the Archduchy of Austria, as a prodrome of a fauna of the same. Contributions to regional studies of Austria under the Enns, 3: 88-122, Vienna 1833 Online at Biodiversity Heritage Library , p. 95.
  2. ^ Alfred Santer Kennard, Bernard Barham Woodward: Notes on the changes necessary in the List of British non-marine Mollusca. 12 pp., Taylor & Francis, London 1914.
  3. ^ Alfred Santer Kennard, Bernard Barham Woodward: Synonymy of the British non-Marine Mollusca (Recent and Post-Tertiary). 447 pp., Trustes of the British Museum, London 1926. Online at Biodiversity Heritage Library (accessed June 13, 2018)
  4. ↑ 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 , pp. 120/21.
  5. ↑ MolluscaBase: Pyramidulidae Kennard & BB Woodward, 1914 (visited June 9, 2018)
  6. ↑ a b c d e Edmund Gittenberger, Ruud A. Bank: A new start in Pyramidula (Gastropoda Pulmonata: Pyramidulidae). Basteria, 60 (1/3): 71-78, Leiden 1996 PDF .
  7. ↑ a b c d Henry Augustus Pilsbry: Manual of conchology, vol. 28: geographic distribution of Pupillidae; Strobilopsidae; Valloniidae and Pleurodiscidae. 226 pp., Conchological Department, Academy of Natural Sciences of Philadelphia, Philadelphia 1935 Online at Biodiversity Heritage Library , pp. 186/87.
  8. ↑ Chung-Chi Hwang: A New Subspecies of Land Snail Genus Pyramidula Fitzinger, 1833 (Gastropoda: Pyramidulidae) from South Taiwan. , 38: P31-39 2015
  9. ↑ Anatolij A. Schileyko, IA Balashov: Pyramidula kuznetsovi sp. nov. - a new species of land molluscs from Nepal (Pulmonata, Pyramidulidae) . Ruthenica. 22 (1): 41-45, 2012
  10. ↑ Igor Balashov, Nina Gural-Sverlova: Terrestrial molluscs of the genus Pyramidula (Pyramidulidae, Pulmonata, Gastropoda) in the East Europe, Central Asia and Adjacent territories. Zoologicheskiĭ zhurnal, 90 (12): 1423-1430, Moscow 2011 ResearchGate
  11. ^ John TC Yen, O. Kühn: Fossil non-marine mollusc faunas from northern China. Meeting reports of the Austrian Academy of Sciences, Mathematical, Natural Science Class, 177 (1/3): 21-71, 1969 PDF
  12. ^ Artie L. Metcalf, Richard A. Smartt: Land Snails of New Mexico. New Mexico Museum of Natural History and Science Bulletin, 10: 1-145, Albuquerque, 1997 Online at Google Books , p. 40.