''Arion silvaticus'' is a
species of air-breathing land
slug
Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a smal ...
, a
terrestrial pulmonate
Pulmonata or pulmonates, is an informal group (previously an order, and before that a subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group includ ...
gastropod
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda ().
This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...
mollusk in the family
Arionidae
Arionidae, common name the "roundback slugs" or "round back slugs" are a taxonomic family of air-breathing land slugs, terrestrial pulmonate gastropod mollusks in the superfamily Arionoidea.
Distribution
The distribution of this family of slug ...
.
Description
Note. In slugs it is often difficult to establish good criteria for identifying species using external features or internal features, as colouration can be quite variable, and the rather plastic anatomy makes diagnostic anatomical features difficult to establish.
Up to 40 mm long. A roundback slug but with a
keel consisting of pale, raised tubercles along the back. In colour the slug is grey to greyish brown becoming whitish down to the sides. There are broad and well marked dark lateral colour bands (white sides below the bands). The sole is whitish or cream. The mucus is transparent or slightly yellowish. Genitalia: atrium large, broad and flattened, epiphallus wider than vas deferens, oviduct wide, half diameter as atrium, spermatheca elongate and somewhat arrow-shaped.
Distribution
This species occurs in countries and islands including:
*
Czech Republic
*
Ukraine[Balashov I. & Gural-Sverlova N. 2012. An annotated checklist of the terrestrial molluscs of Ukraine. ''Journal of Conchology''. 41 (1): 91-109.]
*
Great Britain
*
Ireland
Taxonomy
The original description of the three slugs 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 recent study of these
morphospecies
In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
(typological species) claims that previous studies had shown that body colour in these slugs may be influenced by their diet, and the genital differences were not confirmed by subsequent
multivariate morphometric analyses. Analysis of
alloenzyme and albumen gland proteins had given conflicting results. Also that evidence of interspecific hybridization in places where these predominantly self-fertilizing slugs apparently outcross contradicted their status as
biological species.
Molecular studies led to the conclusion that the three members of ''Carinarion'' are a single species-level taxon.
[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] The name ''Arion fasciatus'' has
priority.
References
External links
''Arion silvaticus''at
Animalbase taxonomy, short description, distribution, biology, status (threats), images
External images
Arion (gastropod)
Gastropods described in 1937
{{Arionidae-stub