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Die Graue Wegschnecke (Arion circumscriptus) ist eine Nacktschnecke aus der Familie der Wegschnecken (Arionidae), die zur Unterordnung der Landlungenschnecken (Stylommatophora) gestellt wird. Die Art ist schwierig von zwei nahe verwandten Arten zu unterscheiden, da die Färbung der Art sehr variabel ist. Neuere Untersuchungen zweifeln die Eigenständigkeit der Art an.
Die Graue Wegschnecke misst ausgestreckt etwa 3 bis 5 cm. Der Rücken ist stahlgrau bis bläulich-grau. Die seitlichen Streifen (Binden) sind relativ breit und meist noch etwas dunkler als der Rücken gefärbt. Sie sind vom Rücken durch einen hellen Streifen abgesetzt. Dieser kann allerdings fast fehlen. Zur Sohle hin folgt ein weiterer heller Streifen. Die Sohle ist weißlich. Auf dem Mantelschild ist dasselbe Muster zu beobachten, die Streifen sind jedoch gegenüber den Streifen am Fuß versetzt. Das Atemloch ist meist ganz oder teilweise vom Seitenstreifen umschlossen.
Die Art lebt in Laubwäldern oft an Fallholz. Sie ernährt sich hauptsächlich von Pilzen und Pilzmyzelien. Sie ist in Mittel- und Westeuropa verbreitet. Im Norden kommt sie bis ins südliche Skandinavien vor. Die Graue Wegschnecke ist wie viele andere ursprünglich europäische Nacktschneckenarten inzwischen auch nach Nordamerika verschleppt worden.
Die Eigenständigkeit der Art wurde 2006 von Sofie Geenen und Mitautoren in Frage gestellt. Sie fanden in den drei Arten Arion fasciatus (Nilsson, 1823) (Gelbstreifige Wegschnecke), Arion silvaticus Lohmander, 1937 (Wald-Wegschnecke) und Arion circumscriptus Johnston, 1828 (Graue Wegschnecke) weder konsistente Merkmale in der Genitalanatomie noch hinreichende Unterschiede bei DNA-Untersuchungen. Die Unterschiede in der Färbung führen sie auf die Etablierung von Farbvarianten durch längere Phasen von Selbstbefruchtung zurück. Rowson et al. (2014) fanden zwischen Arion silvaticus Lohmander, 1937 und Arion circumscriptus Johnston, 1828 ebenfalls keine Unterschiede, sie halten jedoch an Arion fasciatus (Nilsson, 1823) als separate Art fest.
Sollte sich die Interpretation dieser Ergebnisse weiter bestätigen, müssen Arion silvaticus Lohmander, 1937 und Arion circumscriptus Johnston, 1828 zu einer Art (i. e. Arion circumscriptus Johnston, 1828) zusammengefasst werden, während Arion fasciatus (Nilsson, 1823) als eigenständige beibehalten werden kann. Alle drei (oder wahrscheinlich nur zwei) Arten werden in die von einigen Autoren nicht benutzte Untergattung Arion (Carinarion) Hesse, 1926 gestellt. In der ursprünglichen Auffassung als eigenständige Art hatte Arion circumscriptus folgende Synonyme: Arion ambiguus Pollonera, 1889, Arion bourguignati Mabille, 1868, Arion miser Pollonera, 1887 und Arion subcarinatus Pollonera, 1885.
Die Graue Wegschnecke (Arion circumscriptus) ist eine Nacktschnecke aus der Familie der Wegschnecken (Arionidae), die zur Unterordnung der Landlungenschnecken (Stylommatophora) gestellt wird. Die Art ist schwierig von zwei nahe verwandten Arten zu unterscheiden, da die Färbung der Art sehr variabel ist. Neuere Untersuchungen zweifeln die Eigenständigkeit der Art an.
Arion circumscriptus, common name brown-banded arion, is a species of air-breathing land slug, a terrestrial pulmonate gastropod mollusk in the family Arionidae. It is commonest in woodland, occurring across most of Europe, except for more southern regions, and is also widespread in North America. It has been argued that A. circumscriptus is best considered a colour morph of Arion fasciatus.
The subgenus Carinarion Hesse, 1926[2] contains three species—Arion fasciatus, Arion silvaticus and Arion circumscriptus—distinguished on the basis of small differences in pigmentation and in proportions of their genital anatomy.[3][4] Further study of these morphospecies (typological species) revealed that their body colour may be influenced by diet, and that the putative genital differences do not consistently agree with identifications based on pigmentation and allozymes.[5][6] In much of their range these slugs predominantly self-fertilise, leading to distinct genetic strains and thus generating associations between coloration and other phenotypic characters. However, in other regions of Europe where these slugs more often outcross there was evidence of hybridization between strains, contradicting their status as biological species.[7] Moreover, sequencing of mitochondrial DNA revealed that the inferred phylogeny did not match an arrangement in which the three morphologically recognised species form distinct clades.[8]
The suggestion from that work was to treat all three Carinarion taxa as a single species, and this has been followed by recent French literature.[9][10] The name Arion fasciatus then has priority. However, in Britain A. fasciatus s.s. is more distinct than the other two taxa both morphologically and genetically, so that recent British literature considers A. silvaticus as part of A. circumscriptus s.l., but retains A. fasciatus s.s. as distinct even though these taxa may occasionally hybridise.[11] Arion circumscriptus circumscriptus and Arion circumscriptus silvaticus have then been considered as subspecies.[12] Others still consider the situation unresolved and provisionally retain the original three species.[13]
Before the taxonomic work of Lohmander in 1937[14] and Waldén in 1955,[15] and even for some years following, the different species of Carinarion were not distinguished and the name Arion circumscriptus was used to cover all forms.[16][17]
Like with other Arion species, the pneumostome lies in the anterior half of the mantle, and the back is round in cross-section rather than with a keel.[18][19] However, the subgenus Carinarion is distinguished by a row of paler tubercles along the midline of the back, giving the impression of a keel; this is less prominent in adults.[20] Another feature of Carinarion is that the cross-section is bell-shaped, with splayed-out rather than inward-curving sides.[21] The overall colour of A. circumscriptus is a monochrome dark grey (sometimes with a tinge of blue or brown), with a darker dorsal band and a darker lateral band along each side, the one on the right running above the pneumostome. The flanks below are paler. The sole is white or pale grey, and the mucus colourless, or sometimes pale yellow.[22][23] Length reaches 40 mm, or some say up to 50 mm.[22][20]
Several characters have been proposed to distinguish the species within Carinarion, but note the evidence that they should better all be considered colour morphs of one species (see Taxonomy section). Arion fasciatus is distinguished by reaching a larger size and by the yellow or orange flush below the lateral band (which disappears in alcohol),[6] but the other two Carinarion species may also show faint yellow coloration.[21] Dark flecks on the mantle distinguish A. circumscriptus from A. silvaticus and A. fasciatus, and the flanks of A. silvaticus are brighter but with a slightly broader lateral band.[22] Internally, only A. circumscriptus shows strong pigmentation on the epiphallus.[22][20] Classical morphological distinctions based on size of the atrium, epiphallus and oviduct have not been supported when quantitative measurements are compared against identifications based on pigmentation and allozymes.[6] Since the species are predominantly self-fertilizing, amongst the genetic strains present in a local area certain characters may be consistently associated with one another, yet in another area, with different genetic strains, the same characters may not agree.[6]
A study in southern England found that adults were present from January to July, with some of these maturing only as late as May; later maturing adults were smaller than those maturing earlier in the year. Few individuals were found above ground over the dry summer months, but otherwise immature animals of a wide range of sizes were present throughout the year. In late summer and autumn many immature animals were already of adult mass. The life cycle was predominantly annual, but some animals may have taken 18 months to mature.[24] The life cycle appears similar in a study in Moscow gardens, although slightly delayed there by the Russian winter.[25] A study in Michigan grassland also found adults most abundant in spring and summer.[26]
Arion circumscriptus reproduces predominantly by self-fertilization, leading to inbred genetic strains, but the presence of rare heterozygotes demonstrates that mating does occasionally result in outcrossing. The incidence of outcrossing is higher in Central Europe than in North-west Europe.[7]
Arion circumscriptus is most typical of broadleaved woods in temperate climates, occurring in the litter layer, under dead wood and under bark; it sometimes also occurs in other habitats of cultivated land, such as roadsides and waste ground.[27][28] It is only occasional in gardens and not considered a pest.[27][22][29] It occurs up to an altitude of 1300 m in Switzerland.[28]
The species is widespread and common across North-West, Central and Eastern Europe, including southern Scandinavia (naturally to 62° in Sweden, further north still in gardens;[30] also in Iceland).[31] To the east it occurs in the Ukraine[32] and as far as the Vyatka river basin and north Caucasus in Russia.[33] But it is absent in southern Europe (e.g. in the Iberian Peninsula[34] and Greece;[35] only present in northern part of Italy).[36] In the Czech Republic re-identifications have led to it being considered much less common than once thought.[20] In contrast, there has been a real decline in Austria, where it has been assessed as vulnerable.[37]
As an introduction, A. circumscriptus is widespread in the U.S.A. and Canada on both sides of the continent, spreading from gardens into natural habitats.[38]
Parasites of Arion circumscriptus include:
Arion circumscriptus, common name brown-banded arion, is a species of air-breathing land slug, a terrestrial pulmonate gastropod mollusk in the family Arionidae. It is commonest in woodland, occurring across most of Europe, except for more southern regions, and is also widespread in North America. It has been argued that A. circumscriptus is best considered a colour morph of Arion fasciatus.
Arion circumscriptus es una especie de molusco gasterópodo de la familia Arionidae en el orden de los Stylommatophora.
Se encuentra en la República Checa, Gran Bretaña, e Irlanda.[1]
Arion circumscriptus es una especie de molusco gasterópodo de la familia Arionidae en el orden de los Stylommatophora.
Lasilimaetana (Arion circumscriptus) on siruetanoiden heimoon kuuluva kotilo. Se kasvaa 30-50 millimetriä pitkäksi. Sillä on kaksi selvää tummanharmaata tai mustaa yläreunasta vaaleampaa pitkittäisjuovaa kummallakin kyljellä. Lasilimaetanan selkä on harmaa ja kyljet vaaleammat. Se piilottelee kivien ja maahan pudonneiden lehtien alla ja tulee esiin vasta pimeällä. Lasilimaetana syö lakastuneita kasveja. [2]
Lasilimaetana (Arion circumscriptus) on siruetanoiden heimoon kuuluva kotilo. Se kasvaa 30-50 millimetriä pitkäksi. Sillä on kaksi selvää tummanharmaata tai mustaa yläreunasta vaaleampaa pitkittäisjuovaa kummallakin kyljellä. Lasilimaetanan selkä on harmaa ja kyljet vaaleammat. Se piilottelee kivien ja maahan pudonneiden lehtien alla ja tulee esiin vasta pimeällä. Lasilimaetana syö lakastuneita kasveja.
informal group Sigmurethra
Rákasnigill (fræðiheiti: Arion circumscriptus) er tegund af landsniglum sem finnst aðallega í Mið- og Norður-Evrópu. Hann finnst líklega á láglendi um allt land á Íslandi.[1]
Nýlegar rannsókir sýna að þrjár tegundir í ættkvíslinni (Arion (Carinarion) fasciatus, Arion (Carinarion) silvaticus og Arion (Carinarion) circumscriptus) eru líklega í raun ein tegund.[2] Nafnið Arion fasciatus hefur forgang (Principle of Priority).
Meðal sníkjudýra í Arion circumscriptus eru:
Rákasnigill (fræðiheiti: Arion circumscriptus) er tegund af landsniglum sem finnst aðallega í Mið- og Norður-Evrópu. Hann finnst líklega á láglendi um allt land á Íslandi.
Arion circumscriptus is een slakkensoort uit de familie van de Arionidae.[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1828 door Johnston.
Bronnen, noten en/of referenties
Gråflanket skogsnegl (Arion circumscriptus) er et bløtdyr og tilhører de landlevende lungesneglene i familiegruppen skogsnegler. Den er en av «nakensneglene» uten synlig skall.
Gråflanket skogsnegl kan bli 5 cm. lang. Den er ganske lett å kjenne på to markerte svart-grå langsgående striper på hver side av kroppen. Ryggsiden er mørkegrå, med lysere sider.
Gråflanket skogsnegl har to par tentakler. På det øverste paret finnes øyne ute på spissen. Det underste paret brukes til å registrere lukter eller kjemikalier. De har en kappehule som er en del av åndedrettet til sneglen, og den tjenestegjør som en lunge. Man kan lett se åpningen til kappehulen som et hull, normalt på høyre siden av kappen. Skogsnegler har åndehullet foran midten av kappa. Den kan ligne på enkelte arter i familien kjølsnegler (Limacidae), men disse har åndehullet bak midten av kappa og en kjøl på den bakre delen av kroppen.
Gråflanket skogsnegl lever for det meste av ulike plantedeler, som den spiser. Den har ikke tenner, men en raspetunge, som den kan raspe i seg maten med. Men den kan spise døde dyr (åtsler) eller mindre snegler som de kommer over.
Gråflanket skogsnegl finnes på fuktige steder med skygge. Den er aktive om natten når luftfuktigheten er høyere. Om dagen hviler den ofte undere steiner eller i tett vegetasjon. Om været blir for tørt og varmt, lukker den åpningen til kapphulen, mest mulig for å spare på fuktigheten.
Gråflanket skogsnegl er hermafroditt (tvekjønnet). For å kunne legge egg kreves allikevel to snegler, som under parringen, befrukter hverandre. Den legger flere hundre egg i grupper på 20-30 egg, på skyggefulle fuktige steder. Etter noen uker klekker eggene. De nyklekkete sneglene ser ut som miniatyrer av de voksne individene. Utviklingstiden til et voksent individ kan variere etter arten, men mellom seks og sju måneder er vanlig.
Gråflanket skogsnegl (Arion circumscriptus) er et bløtdyr og tilhører de landlevende lungesneglene i familiegruppen skogsnegler. Den er en av «nakensneglene» uten synlig skall.
