Amastra | |
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Amastra elongata shell | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Gastropoda |
Order: | Stylommatophora |
Superfamily: | Pupilloidea |
Family: | Amastridae |
Subfamily: | Amastrinae |
Genus: | Amastra H. Adams & A. Adams, 1855 |
Type species | |
Achatinella magnaC. B. Adams, 1851 | |
Synonyms | |
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Amastra is a genus of small air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Amastridae. [1]
Like many Hawaiian land snails, species in this genus have adapted to a specific ecological niche and have evolved in relative isolation. They are thriving in wet or moderately wet forested areas.
Many of the species in this genus have become extinct in recent times or have become critically endangered through habitat loss or predation. This loss is often highlighted as part of the broader biodiversity crisis faced by the Hawaiian Islands.
The elongated shell is typically dextral (but some are sinistral), ranging from globose-conic to oblong-conic in shape. It may be umbilicate or imperforate. he shell surface might show growth striations or a fine malleation. The coloration varies, often appearing dull or dark, but sometimes light with a dull, darker, or yellowish cuticle. The shell consists of 5½ to 8 whorls, with the spire and apex conical in shape. The aperture is ovate, and the outer lip is not expanded but is often thickened internally. The columella features a spiral lamella that penetrates about half a whorl, and is present at all stages of growth observed. Above the lamella, the axis is slightly sinuous.
The species is viviparous. The jaw is vertically striate, and the teeth are arranged in nearly straight transverse rows, exhibiting the typical quadrate form. The central teeth are narrow with small, sinuous cusps. [2]
This genus is endemic to the Hawaiian Islands.
Species within the genus Amastra include:
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