Arion is a genus of air-breathing land slugs in the family Arionidae, the roundback slugs.
Most species of this Palearctic genus are native to the Iberian Peninsula.
Species can be difficult to distinguish from one another upon cursory examination, because individuals of a species can vary in color and there are few obvious differences between taxa. The color of an individual can be influenced by its diet.
Some Arion are known as pests, such as A. lusitanicus auct. non Mabille (= A. vulgaris), which damages agricultural crops and ornamental plants, and A. rufus, a familiar garden pest. Arion slugs are often transported internationally in shipments of plant products and mushrooms. Arion slugs have been identified in North America and Australia as invasive species, altering the plants of ecosystems through seed predation and competing with native slugs.
Contents
Species
There are over 40 species in the genus.
Species include:
Synonyms
Arion alpinus Pollonera, 1887: synonym of Arion intermedius Normand, 1852 (junior subjective synonym)
Arion andersonii J. G. Cooper, 1872: synonym of Prophysaon andersonii (J. G. Cooper, 1872) (superseded combination)
Arion anguloi Martín & B. Gómez, 1988: synonym of Arion urbiae de Winter, 1986 (a suggested synonym)
Arion aterrimus L. Pfeiffer & J. E. Gray, 1855: synonym of Oopelta aterrima (L. Pfeiffer & J. E. Gray, 1855) (original combination)
Arion austeniana G. Nevill, 1880 (nomen nudum)
Arion coerulens Collinge, 1897: synonym of Arion distinctus Mabille, 1868
Arion cottianus Pollonera, 1889: synonym of Arion distinctus Mabille, 1868
Arion elongatus Collinge, 1894: synonym of Arion hortensis A. Férussac, 1819
Arion empiricorum A. Férussac, 1819: synonym of Arion ater (Linnaeus, 1758) (junior subjective synonym)
Arion foliolatus A. Gould, 1851: synonym of Prophysaon foliolatum (A. Gould, 1851) (original combination)
Arion hessei Simroth, 1894: synonym of Arion distinctus Mabille, 1868
† Arion hochheimensis Wenz, 1911 (apparently no gastropod but calcareous excretions of Lumbricidae)
† Arion kinkelini Wenz, 1911 (apparently no gastropod but calcareous excretions of Lumbricidae)
Etymology
The name Arion is in reference to Aelion's De Natura Animalium, which features a story about areíones - snails which leave their shells behind to feed, thus outsmarting predators who attack the empty shells.
Mentioning in literature and folklore
Larger Arion slugs frequently appear in various forms of traditional culture, including folk traditions, children's rhymes, and historical documentation of their practical uses.
In pre-industrial Sweden, there are historical accounts, like the one in Lorens Wolter Rothof's 1762 book, detailing the unusual practice of using the black slug (Arion ater) as a source of grease to lubricate wooden wagon axles.