Semi-slugs, also spelled semislugs, are land gastropods whose shells are too small for them to retract into, but not quite vestigial.1 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.2 There exist about 1,000 species of semi-slugs in comparison to about only 500 species of slugs.1
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, Vitrinobrachium3
- 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.2
- Neotropics
- family Amphibulimidae: Amphibulima, Gaeotis2
- family Xanthonychidae: Cryptostrakon, Semiconchula, Xanthonyx2
- family Pleurodontidae: Coloniconcha prima2
- Tropical Africa
- family Urocyclidae: Gymnarion
References
References
- Burton D. W. (1982). "How to be sluggish". Tuatara 25(2): 48–63. HTM.
- 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.
- Giusti, F.; Fiorentino, V.; Benocci, A.; Manganelli, G. (2011). "A Survey of Vitrinid Land Snails (Gastropoda: Pulmonata: Limacoidea)". Malacologia. 53 (2): 279–363. doi:10.4002/040.053.0206. ISSN 0076-2997. S2CID 86724021.