Mediterranean heather snail

Mediterranean heather snail
Mediterranean heather snail ( Cernuella virgata )
Systematics
Superfamily : Helicoidea Family : Geomitridae Subfamily : Helicellinae Tribe : Cernuellini Genre : Cernuella Type : Mediterranean heather snail
Scientific name
Cernuella virgata
( da Costa , 1778)

The Mediterranean heather snail ( Cernuella virgata ), also known as sand heather snail, is a species of snail belonging to the Geomitridae family from the order of the terrestrial lung snails (Stylommatophora).

features

The rounded, conical to slightly pressed case measures 6 to 19 mm in height and 8 to 25 mm in width (4 to 8 × 6 to 15 mm or 8 to 15 × 12 to 23 mm). This results in a width / height index of 1.11-1.32-1.51 (n = 135). In the adult stage there are five to seven regularly increasing, convexly arched convolutions that are rounded on the periphery. The seam is only weakly to moderately deep. The outer line is convex. The navel is narrow and not, or only very slightly, eccentric; the index umbilical width to housing width varies from 0.065-0.10-0.135 (n = 138). The last turn drops slightly towards the mouth. It is round in cross-section, in larger, pressed specimens it is also egg-shaped and slightly edged. The edge of the mouth is sharp and only slightly turned over in the area of ​​the navel, protruding slightly above the navel. A more or less strong white or reddish (brownish) lip is formed in the mouth near the mouth edge.

The shell of the housing is whitish or reddish-yellow in color. The drawing is very variable. The most common specimens appear with dark brown bands, one band above the periphery, one band on the periphery, and three to four narrower bands on the bottom. The ligaments are partially weakened, interrupted, dissolved in spots or fused or almost completely extinguished. The surface is largely smooth, only provided with rather irregular growth strips.

Pale shape

Love arrow

The animals are hermaphrodites, but cannot fertilize themselves. In the female genital tract, the genital atrium is almost always wider than it is long, sometimes almost non-existent. The two arrow bags sit at the distal end of the genital atrium. The outer, bulbous arrow sack is only slightly to much larger than the inner arrow sack. In animals from Italy and the former Yugoslavia, the inner arrow pouch protrudes more or less clearly over the outer arrow pouch. The arrow in the outer arrow sack is slightly curved and has a lance-shaped widened tip. It is flattened in cross section with a central channel. The free vagina between the arrow sacks and the glandulae mucosae is wider than it is long. The glandulae mucosae divide into 7 to 25 branches (n = 35). The spermatic duct is long and tortuous. A flagellum (blind sac) is formed at the point of entry into the epiphallus. The epiphallus is one and a half to over three times (usually about twice) as long as the flagellum. The epiphallus is about as long as the penis. The penile retractor muscle starts at the transition from the epiphallus to the penis. The stem of the spermathec is significantly longer than the seminal vesicle itself and can be widened at the base.

The soft body is light gray on the foot and sides and dark gray to almost black on the back. The back is covered with comparatively large, elongated tubercles that are visible to the naked eye. The tentacles are gray and up to eight mm long.

Similar species

The shell of the Mediterranean heather snail is highly variable in design, shape and size. It is most similar to the cases of the closely related Cernuella aginnica and Rotmündigen heath snail ( Cernuella neglecta ). Both types have a more flattened housing and each have a further navel.

Geographical distribution and habitat

The range of the species stretches from the British Isles, Netherlands, Belgium, France, Spain, and the coastal regions of the Mediterranean Sea (except the eastern coasts), Bulgaria, Crimea to Novorossiysk (Russia). However, it has already been widely abducted today. There are colonies of the Mediterranean heather snail in Germany. In the city of Kiel there was a stable colony for many years; the area is built over today. But today it also occurs in Baden-Württemberg and on the island of Helgoland. The species was first observed in Austria in 2003. It was introduced to Australia at the beginning of the 20th century. Today there are also colonies in Turkey and the USA.

The Mediterranean heather snail prefers moderately dry and open locations on calcareous soil, e.g. B. overgrown dunes, dry grass, stubble fields, rows of hedges, roadsides, wasteland and fallow land.

Way of life

The Mediterranean heather snail feeds on dry and decaying plant material, but eats fresh plant material.

Like other heather snails, the species has a one or two year life cycle. Copulation usually takes place in late summer or early autumn, after the onset of rainfall.

According to observations from France, the animals laid 30 to 80 round eggs (100 to 200 eggs) with a diameter of about 1.5 mm between September and November. The eggs have a whitish, transparent shell and are placed in the leaf litter or one to two centimeters in the soil. The young hatch after about 15 to 20 days. They grow little in mild winters; however, growth accelerates in spring. Usually they reach sexual maturity in the year after next; after the eggs are laid, the animals die.

During long periods of drought, the animals often crawl in large numbers on tall plants, but also on walls to escape the heat of the ground and maintain a drought. The mouth is closed with a diaphragm. The population density can be very high, up to around 200 animals per square meter, in wet years even up to 400 animals per square meter have been counted. The biomass of the snails by far exceeds the plant biomass on the same square meter. However, the population density regulates itself to a certain extent. With high population densities, the number of young animals produced decreases, the growth rate of the animals decreases and the lifespan of the adult animals is also shorter.

Taxonomy

The taxon was set up in 1778 by Emanuel Mendes da Costa as Cochlea virgata . The species is de facto type of the genus Cernuella Schlueter, 1838, as the formal type Helix variabilis Draparnaud, 1801 is a younger synonym of Cernuella virgata .

Cernuella cisalpina is regarded by Bernhard Hausdorf and Jan Sauer (2009) as a synonym for Cernuella virgata . In the opinion of these authors, there is no evidence that the two taxa are reproductively isolated. In her opinion, there are no differences in the genital apparatus. In addition, all transitions are present in the shape and size of the housing, and so far there has also been no locality where these two taxa occur sympatric with each other. In contrast, a molecular genetic study by Manganelli et al. (2005) there are clear differences between Cernuella virgata and Cernuella cisalpina . There are also different localities in Italy, where both taxa occur sympatric. Cernuella cisalpina must surely beacceptedas a bona species (see Welter Schultes).

The Mediterranean heather snail as a pest

In Europe, the presence of the Mediterranean heather snail is usually not a major problem.

The Mediterranean heather snail was imported into the USA, Australia, New Zealand and other countries as a neozoon in the 20th century , where it sometimes caused great damage, especially in grain fields, and was therefore classified as a pest there. Imports of bricks, natural stone, wood and fruits are therefore strictly controlled in this way. In 2010 the export of 23 tons of apples from France to Israel failed because living specimens of the Carthusian snail ( Monacha cartusiana (OF Müller, 1774)) and the Mediterranean heather snail ( Cernuella virgata (da Costa, 1778)) were found in the cargo .

In Australia, the Mediterranean heather snail has now become a problem for grain cultivation. In addition to the feeding damage, which is mainly caused to the seeds, the contamination of the grain with living snails is the greater damage or a cost factor, since the grain has to be cleaned or can only be sold as feed grain at a lower price. The grain can no longer be exported, as many countries have strict quarantine regulations to prevent the introduction of the Mediterranean heather snail.

Due to the mass increase in pastures and meadows, pastures as well as hay can become unusable due to the slime tracks of the animals, because the cattle neither eat the grass, which is contaminated with slime by the snails, nor the hay.

Dora Godan (1983) lists the following forage and useful plants (leaves, seedlings and young plants) that are damaged by the Mediterranean heather snail: clover ( Trifolium ), alfalfa ( Medicago sativa ), saspars ( Onobrychis spp.), Rapeseed ( Brassica napus ), artichoke ( Cynara cardunculus ), barley ( Hordeum vulgare ), horehound ( Marrubium vulgare ), beans ( Phaseolus spp.), Pea ( Pisum sativum ), yellow worm ( Reseda lutea ), wrinkled rapeseed yolk ( Rapistrum rugosum ) and Wheat ( Triticum spp.).

The Mediterranean heather snail as an intermediate host for parasites

The Cernuella species are intermediate hosts in the transmission of Aelurostrongylus abstrusus (cat lungworm), Brachylaima cribbi (intestinal trematode; also in humans) and small liver fluke ( Dicrocoelium dendriticum ). They can also transmit Cystocaulus ocreatus , Muellerius capillaris, and Neostrongylus linearis to livestock. Cernuella virgata is also an intermediate host for the tapeworm Davainea proglottina , which can infect poultry.

supporting documents

literature

• Klaus Bogon: Land snails biology, ecology, biotope protection. 404 p., Natur Verlag, Augsburg 1990 ISBN 3-89440-002-1 (p. 308/9)
• John PM Clerx, Edmund Gittenberger: A few things about Cernuella. Zoological Mededelingen Leiden, 52 (4): 27-56, 1977 PDF
• Edmund Gittenberger: On Cernuella virgata (Da Costa, 1778) and two Iberian Xerosecta species (Mollusca: Gastropoda Pulmonata: Hygromiidae). Zoological Mededelingen Leiden, 67 (18): 295-302, Leiden 1993 PDF
• 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 (p. 245)

Individual evidence

1. ^ Rosina Fechter and Gerhard Falkner: Molluscs. 287 p., Mosaik-Verlag, Munich 1990 (Steinbach's Nature Guide 10), ISBN 3-570-03414-3 , (p. 210)
2. ^ Vollrath Wiese: The land snails of Germany. 352 pp., Quelle & Meyer, Wiebelsheim 2014 ISBN 978-3-494-01551-4 (p. 266)
3. ↑ Francisco W. Welter-Schultes: European non-marine molluscs, a guide for species identification = identification book for European land and freshwater mollusks. A1-A3 S., 679 S., Q1-Q78 S., Göttingen, Planet Poster Ed., 2012 ISBN 3-933922-75-5 , ISBN 978-3-933922-75-5 (S. 537)
4. ↑ Anatolij A. Schileyko: Treatise on Recent terrestrial pulmonate molluscs, Part 14 Helicodontidae, Ciliellidae, Hygromiidae. Ruthenica, Supplement 2 (14): 1907-2047, Moscow 2006 ISSN  0136-0027 (publication date corrected in vol. 15, p. 2115) (p. 1986)
5. ↑ Wolfgang Fischer, Michael Duda: Contributions to the knowledge of the mollusc fauna of Austria VII. Cernuella virgata (Da Costa 1778) new for the mollusc fauna of Vienna, as well as remarks on the spread of Monacha cantiana (Montagu 1803), Cernuella neglecta (Draparnaud 1805), Hygromia cinctella ( Draparnaud 1801) and Cornu aspersum (OF Müller 1774) in Lower Austria and Vienna (Mollusca: Gastropoda). News sheet of the First Vorarlberg Malacological Society, 12: 10–14, Rankweil 2004 PDF
6. ^ Carnegie Museum of Natural History: Virginia Land Snails: Cernuella virgata (da Costa, 1778)
7. ↑ ^{a b} United States Department of Agriculture. Animal and Plant Health Inspection Service, Plant Protection and Quarantine: New Pest Response Guidelines - Temperate Terrestrial Gastropods PDF ( Memento of the original from September 25, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. 
8. ↑ ^{a b} Molet, T. 2014. CPHST Pest Datasheet for Cernuella spp. USDA-APHIS-PPQ-CPHST. PDF
9. ↑ Emanuel Mendes da Costa: Historia naturalis testaceorum Britanniæ, or, the British conchology; containing the descriptions and other particulars of natural history of the shells of Great Britain and Ireland: illustrated with figures. In English and French. London, Millan, White, Emsley & Robson 1778. Online at www.biodiversitylibrary.org (p. 79)
10. ↑ Fauna Europaea: Cernuella (Cernuella) virgata (Da Costa 1778)
11. ^ Bernhard Hausdorf, Jan Sauer: Revision of the Helicellinae of Crete (Gastropoda: Hygromiidae). Zoological Journal of the Linnean Society, 157: 373-419, 2009 doi : 10.1111 / j.1096-3642.2008.00504.x
12. ^ Giuseppe Manganelli, Nicola Salomone, Folco Giusti: A molecular approach to the phylogenetic relationships of the western palaearctic Helicoidea (Gastropoda: Stylommatophora). Biological Journal of the Linnean Society, 85: 501-512, 2005 doi : 10.1111 / j.1095-8312.2005.00514.x .
13. ↑ Henk K. Mienis, Svetlana Vaisman: The presence of life specimens of Monacha cartusiana (OF Müller, 1774) and Cernuella virgata (Da Costa, 1778) (Mollusca, Gastropoda, Hygromiidae) has prevented the import of 23 tons of apples from France into Israel. MalaCo, 6: 268–269, 2010 PDF ( Memento of the original from September 25, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. 
14. ↑ GM Barker: Molluscs as Crop Pest.
15. ↑ Dora Godan: Pest slugs and snails. X + 445 S. Berlin u. a., Springer, 1983.