Semi-slug

Semi-slugs, also spelled semislugs, are land gastropods whose shells are too small for them to retract into, but not quite vestigial. The shell of some semi-slugs may not be easily visible on casual inspection, because the shell may be covered over with the mantle.

This is a type of gastropod that is intermediate between a slug (without an external shell) and a land snail (with a large enough shell to retract completely into).

There exist a number of gastropod families that have semi-slug species. There exist about 1,000 species of semi-slugs in comparison to about only 500 species of slugs.

Examples

Semi-slugs have a worldwide distribution and have evolved in several families; genera include:

  • Palearctic and Nearctic
    • family Parmacellidae: Cryptella
    • family Vitrinidae: Eucobresia, Semilimax, Vitrina, Vitrinobrachium
  • Asia - Pacific
    • family Ariophantidae: Parmarion, Ratnadvipia, Varadia
    • family Helicarionidae: Attenborougharion, Helicarion, Howearion, Ibycus, Parmellops, Ubiquitarion
    • Semi-slugs also exist but are exceptional in the Camaenidae.
  • Neotropics
    • family Amphibulimidae: Amphibulima, Gaeotis
    • family Xanthonychidae: Cryptostrakon, Semiconchula, Xanthonyx
    • family Pleurodontidae: Coloniconcha prima
  • Tropical Africa
    • family Urocyclidae: Gymnarion [citation needed]

See also

  • "Leatherleaf slugs" - Veronicellidae

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