Truncatella (gastropod)

Truncatella is a genus of very small land snails with an operculum, terrestrial gastropod mollusks in the family Truncatellidae. These small and minute snails live on land, very close to seawater. They walk with a strange looping action, and the adults have truncated shells. Many of the species are small enough to be considered micromollusks.

Truncatella
Two live individuals of Truncatella subcylindrica: a juvenile on the left, and an adult on the right
Scientific classification
Kingdom:
Animalia
Phylum:
Mollusca
Class:
Gastropoda
(unranked):
clade Caenogastropoda
clade Hypsogastropoda
clade Littorinimorpha
Superfamily:
Truncatelloidea
Family:
Truncatellidae
Subfamily:
Truncatellinae
Genus:
Truncatella

Risso, 1826[1]

Truncatella is the type genus of the family Truncatellidae.[2]

Distribution and habitat

This genus occurs in tropical and subtropical areas. The various species of Truncatella are pantropical in distribution, with a few exceptions such as Truncatella truncatula and Truncatella subcylindrica.

Most of the species in this genus live in a habitat that is neither fully terrestrial nor fully marine: they live under plant debris near high tide level, where they are occasionally wetted with seawater by waves. A small minority of the species are fully terrestrial.

These small snails are typically found associated with drifts of plant material, where their eggs are deposited.[3]

The adaptations of these land snails to the terrestrial environment are not so perfect as they are in the more usual pulmonate land snails, and their terrestrial adaptations may in fact be comparatively recent.[4]

Species
Shells of Truncatella scalarina
Shells of Truncatella vincentiana

The genus Truncatella was erected by Antoine Risso (Risso, 1826)[1] for T. costulata (now T. subcylindrica), which is the type species for this genus.

There are several genera within the Truncatellidae, but the eponymous genus Truncatella is the largest (in terms of number of species); other genera in the family are Geomelania, Taheitia, and Blandiella.[5][6][7]

There are approximately 30 species in the genus Truncatella, including:

Description
From left: Truncatella bahamensis (holotype), T. bilabiata bilabiata, T. pulchella.[5]

As implied by the name, these snails are notable for the way they modify their elongated shells as they mature, breaking off several of the apical whorls, and forming a relatively smooth seal for the remainder of the shell.

Locomotion

The method of locomotion used by Truncatella is unusual.[34] Instead of gliding over a slime trail using minute waves in its foot, Truncatella uses a very large and muscular proboscis to reach ahead and grasp a surface, at which point the small foot releases its hold and the proboscis contracts to pull the animal forward, after which the entire procedure is usually repeated.[35]

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References
  1. Risso A. (1826). Histoire naturelle des principales productions de l'Europe méridionale et particulièrement de celles des environs de Nice et des Alpes Maritimes. Vol. 4. no publisher listed, Paris. page 124.
  2. Bouchet, Philippe; Rocroi, Jean-Pierre; Frýda, Jiri; Hausdorf, Bernard; Ponder, Winston; Valdés, Ángel & Warén, Anders (2005). "Classification and nomenclator of gastropod families". Malacologia. Hackenheim, Germany: ConchBooks. 47 (1–2): 1–397. ISBN 3-925919-72-4. ISSN 0076-2997.
  3. Ross, Landon T. (1969). Notes on the life history of Truncatella caribaeensis Reeve. American Malacological Union Ann. Rept. 1969:35-36.
  4. Rosenberg, Gary (1996). Independent evolution of terrestriality in Atlantic truncatellid gastropods. Evolution 50(2): 682-693.
  5. Ross, Landon T. (1970). The anatomy of Truncatella Risso 1826 (Mollusca: Prosobranchia), and a revision of the genus in the Gulf of Mexico and the Caribbean Sea. unpublished Florida State Univ. dissertation. Retrieved on September 2007.
  6. Clench, William J. & Ruth D. Turner (1948), A catalogue of the family Truncatellidae with notes and descriptions of new species. Occ. Pap. Mollusks, Harvard Univ. 1: 157-212.
  7. Clench, William J. & Ruth D. Turner (1948), The genus Truncatella in the western Atlantic. Johnsonia 2: 149-164.
  8. Rosenberg, G. (2010). Truncatella avenacea Garrett, 1887. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=527390 on 2011-06-13
  9. Rosenberg, G. (2011). Truncatella bairdiana C. B. Adams, 1852. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=557942 on 2011-06-13
  10. Rosenberg, G. (2011). Truncatella brazieri Cox, 1868. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=557943 on 2011-06-13
  11. Rosenberg, G. (2011). Truncatella californica Pfeiffer, 1857. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=557944 on 2011-06-13
  12. WoRMS (2010). Truncatella caribaeensis Reeve, 1842. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=419688 on 2011-06-13
  13. Rosenberg, G. (2011). Truncatella ceylanica Pfeiffer, 1857. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=557945 on 2011-06-13
  14. WoRMS (2010). Truncatella clathrus Lowe, 1832. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=419689 on 2011-06-13
  15. Rosenberg, G. (2011). Truncatella diaphana Gassies, 1869. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=557946 on 2011-06-13
  16. Truncatella. OBIS, accessed 13 June 2011.
  17. Rosenberg, G. (2010). Truncatella granum Garrett, 1872. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=527386 on 2011-06-13
  18. Rosenberg, G. (2010). Truncatella guerinii Villa & Villa, 1841. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=527391 on 2011-06-13
  19. Rosenberg, G. (2010). Truncatella kiusiuensis Pilsbry, 1902. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=527385 on 2011-06-13
  20. Rosenberg, G. (2010). Truncatella marginata Küster, 1855. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=527383 on 2011-06-13
  21. Rosenberg, G. (2011). Truncatella obscura Morelet, 1882. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=557947 on 2011-06-13
  22. Rosenberg, G. (2011). Truncatella pellucida Dohrn, 1860. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=557948 on 2011-06-13
  23. Rosenberg, G. (2010). Truncatella pulchella Pfeiffer, 1839. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=419690 on 2011-06-13
  24. "Mollusca" Archived 26 June 2012 at the Wayback Machine. Diversidad Biológica Cubana, accessed 23 March 2011.
  25. Truncatella pulchella. Database of Western Atlantic Marine Mollusca.
  26. Rosenberg, G. (2011). Truncatella quadrasi Möllendorff, 1893. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=557949 on 2011-06-13
  27. Rosenberg, G. (2010). Truncatella rostrata Gould, 1848. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=527392 on 2011-06-13
  28. Rosenberg, G. (2010). Truncatella rustica Mousson, 1865. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=527384 on 2011-06-13
  29. Rosenberg, G. (2011). Truncatella scalarina Cox, 1867. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=557950 on 2011-06-13
  30. Rosenberg, G. (2010). Truncatella scalaris (Michaud, 1830). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=527382 on 2011-06-13
  31. Rosenberg, G. (2011). Truncatella stimpsonii Stearns, 1872. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=557951 on 2011-06-13
  32. Gofas, S. (2011). Truncatella subcylindrica (Linnaeus, 1767). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=141850 on 2011-06-13
  33. Rosenberg, G. (2010). Truncatella thaanumi Clench & Turner, 1948. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=527387 on 2011-06-13
  34. Pilsbry, H. A. & A. P. Brown (1914), The method of progression in Truncatella, Proc. Acad. Nat. Sci. Philadelphia 66: 426-428.
  35. Örstan, Aydin. How Truncatella caribaeensis moves. blog for 15 June 2006. http://snailstales.blogspot.com/2006/06/how-truncatella-caribaeensis-moves.html
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