Truncatella is the type genus of the family Truncatellidae.[2]
Description
From left: Truncatella bahamensis (holotype), T. bilabiata bilabiata, T. pulchella.[3]
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 apicalwhorls, and forming a relatively smooth seal for the remainder of the shell.
Locomotion
The method of locomotion used by Truncatella is unusual.[4] 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.[5]
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.[6]
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.[7]
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.[3][8][9]
There are approximately 30 species in the genus Truncatella, including:
Truncatella wrighti L. Pfeiffer, 1862: synonym of Geomelania lirata (Poey, 1858)
Truncatella yorkensis Cox, 1868: synonym of Truncatella guerinii A. Villa & J. B. Villa, 1841
References
^ abRisso 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.
^ abRoss, 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.[1]
^Pilsbry, H. A. & A. P. Brown (1914), The method of progression in Truncatella, Proc. Acad. Nat. Sci. Philadelphia 66: 426-428.
^Ross, Landon T. (1969). Notes on the life history of Truncatella caribaeensis Reeve. American Malacological Union Ann. Rept. 1969:35-36.
^Rosenberg, Gary (1996). Independent evolution of terrestriality in Atlantic truncatellid gastropods. Evolution 50(2): 682-693.
^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.
^Clench, William J. & Ruth D. Turner (1948), The genus Truncatella in the western Atlantic. Johnsonia 2: 149-164.
