Arion circumscriptus

Arion circumscriptus, common name Brown-banded arion, is a species of air-breathing land slug, a terrestrial pulmonate gastropod mollusk in the family Arionidae.

Brown-banded arion
Brown-banded arion (Arion circumscriptus), partially retracted
Scientific classification
Kingdom:
Animalia
Phylum:
Mollusca
Class:
Gastropoda
(unranked):
clade Heterobranchia
clade Euthyneura
clade Panpulmonata
clade Eupulmonata
clade Stylommatophora
informal group Sigmurethra
Superfamily:
Arionoidea
Family:
Arionidae
Genus:
Arion
Species:
A. circumscriptus
Binomial name
Arion circumscriptus
Johnston, 1828

Description

This slug species is up to 40mm when mature.[1][2] It is listed as 50 mm long in Welter-Schultes [3] It is a roundback slug. Its color is dark grey (sometimes with bluish hue) or brown. The mantle has dark spots. The sides are usually lighter near the foot-fringe, and have one dark longitudinal band on each side; the one on the right runs above the pneumostome. The dorsum often has a very slight keel and the slug is bell-shaped in transverse section when it is contracted. The sole is whitish, and the mucus colourless.

Genitalia: the atrium is large; the epiphallus is heavily pigmented and wider than the vas deferens; the oviduct is short and not narrow; the spermatheca is elongate.[3]

Distribution

Arion circumscriptus is found mainly in the mid and northern latitudes in Europe. The distribution type is European Temperate.

This species occurs in countries and islands including:

This species has been introduced in:

Parasites

Parasites of Arion circumscriptus include:

Taxonomy

The original description of the three slug species in the subgenus Carinarion, Arion (Carinarion) fasciatus, Arion (Carinarion) silvaticus and Arion (Carinarion) circumscriptus, was based on small differences in body pigmentation and details of the genital anatomy. A 2006 study of these morphospecies (typological species) claims that previous studies had shown that body colour in these slugs may be influenced by their diet, and that the putative genital differences were not confirmed by subsequent multivariate morphometric analyses. Analysis of alloenzyme and albumen gland proteins gave conflicting results. Also there was evidence of interspecific hybridization in places where these predominantly self-fertilizing slugs apparently outcross, contradicting their status as biological species. Molecular studies led to the conclusion that the three members of Carinarion are a single species-level taxon.[7] The name Arion fasciatus has priority.

References
  1. "Arion fasciatus group: Arion circumscriptus". Terrestrial Mollusc Tool. University of Florida. Retrieved 20 February 2013.
  2. "Arion circumscriptus Johnston, 1828 Brown-banded Arion". Evergreen State College. Retrieved 20 February 2013.
  3. Animalbase (Welter-Schultes).
  4. Balashov I. & Gural-Sverlova N. 2012. An annotated checklist of the terrestrial molluscs of Ukraine. Journal of Conchology. 41 (1): 91-109.
  5. Land Snails of Pennsylvania Archived 2009-01-23 at the Wayback Machine. accessed 20 January 2009.
  6. Michigan Department of Natural Resources and Environment. "Brainworm". accessed 14 December 2010.
  7. Sofie Geenen, Kurt Jordaens, Thierry Backeljau: Molecular systematics of the Carinarion complex (Mollusca: Gastropoda: Pulmonata): a taxonomic riddle caused by a mixed breeding system. Biological Journal of the Linnean Society, 89(4): 589–604, London 2006 doi:10.1111/j.1095-8312.2006.00693.x
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