Semi-slug explained

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-slugs species.^[1] There exist about 1,000 species of semi-slugs in comparison to about only 500 species of slugs.^[2]

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^[3]
• 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

See also

• "Leatherleaf slugs" - Veronicellidae

Notes and References

1. Breure A. S. H. (2010). "The rediscovery of a semi-slug: Coloniconcha prima Pilsbry, 1933 (Gastropoda, Pleurodontidae) from Hispaniola". Basteria 74(4-6): 78-86.
2. Burton D. W. (1982). "How to be sluggish". Tuatara 25(2): 48-63. HTM.
3. Giusti . F. . Fiorentino . V. . Benocci . A. . Manganelli . G. . 2011 . A Survey of Vitrinid Land Snails (Gastropoda: Pulmonata: Limacoidea) . Malacologia . en . 53 . 2 . 279–363 . 10.4002/040.053.0206 . 86724021 . 0076-2997.