Spermodea
| Spermodea | ||||||||||||
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Beehives ( Spermodea lamellata ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Spermodea | ||||||||||||
| Westerlund , 1902 |
Spermodea is a genus of snails from the family of grass snails (Valloniidae); the family belongs to the subordination of land snails (Stylommatophora). The oldest species of the genus come from the Upper Oligocene ( Palaeogene ).
features
The housings are spherical with a low-conical apex. They measure 1.5 to 3 mm in height and 1.9 to 2.3 mm in width. The up to six moderately arched turns increase slowly and regularly. They are separated from each other by shallow seams. The embryonic convolutions are very finely granulated on the surface. The later coils bear fine, lamellate ribs consisting of periostracum. The mouth is crescent-shaped, the edge of the mouth is thin and not turned over. The navel is open and narrowly cylindrical.
The so far anatomically examined species of the genus were aphallic, i. H. in the hermaphroditic genitalia the male ducts are reduced. The stem of the spermathec is moderately short, the bladder oblong-ovoid.
Geographical distribution and habitat
The species of the genus are common in western, central and northern Europe. In Norway the distribution area extends up to 64 ° north latitude. In south-western Europe there are deposits in Portugal and northern Spain. Occurrences in Latvia are reported to the east.
Way of life
Little is known about the way of life of the Spermodea species. So far only a few specimens have been anatomically examined and these specimens have been aphallic, i.e. This means that the animals can only reproduce through self-fertilization. It remains to be seen, however, whether this applies to all recent species, or whether a small percentage of the population is not euphallic in some species, as in other species of grass snail.
Taxonomy
The taxon Spermodea was proposed by Carl Agardh Westerlund in 1902 . He added two species: Helix lamellata Jeffreys, 1830 and Helix spermatia Castro, 1887. In 1926, Henry Augustus Pilsbry designated Helix lamellata Jeffreys, 1830, as a type species. The following species are currently included in the genus:
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Spermodea Westerlund, 1902
- † Spermodea augusti Schlickum, 1978, Pliocene
- † Spermodea candida Falkner, 1974, Upper Miocene
- † Spermodea demarcqui Schlickum & Truc, 1972, Pliocene
- Beehives ( Spermodea lamellata (Jeffreys, 1830))
- Spermodea monas (Morelet, 1860)
- † Spermodea plicatella (Reuss, 1849), Chattium , Aquitanium , Burdigalium
- † Spermodea puisseguri Schlickum & Truc, 1972, Pliocene
- (?) Spermodea spermatia (Castro, 1887)
supporting documents
literature
- Gerhard Falkner: About Acanthinulinae from the Upper Miocene of southern Germany. Archive for Molluscology, 104: 229-245, Frankfurt / Main 1974.
- 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 .
- W. Richard Schlickum: To the Upper Pannon mollusc fauna of Öcs. Archive for Molluscology, 108: 245-261, Frankfurt / Main 1978.
- W. Richard Schlickum, G. Truc: New Jungpliocene species of the genera Acanthinula Beck and Spermodea Westerlund. Archives for Molluscology, 102: 189-193, Frankfurt / Main, 1972.
Individual evidence
- ↑ Hartmut Nordsieck (V.2014): Annotated check-list of the genera of fossil land snails (Stylommatophora) of western and central Europe (Cretaceous - Pliocene) ( Memento of the original from July 14, 2014 in the Internet Archive ) Info: The archive link was used automatically and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Westerlund, CA 1902. Methodus dispositionis conchyliorum extramarinorum in Regione palaearctica viventium, familias, genera, subgenera, et stirpes sistens. - Rad Yugoslavenske Akademije Znanosti i Umjetnosti, Matematičko-Prirodoslovni Razred, 151 (32): 82-139. Zagreb (p. 90).
- ^ Henry Augustus Pilsbry: Manual of Conchology. Second Series: Pulmonata. Vol. 27. Pupillidae (Orculinae, Pagodulinae, Acanthinulinae, etc). Pp. I-IV, 1-369, Philadelphia 1922-1926. Online at www.biodiversitylibrary.org (p. 186)
