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Amastra nigra

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Amastra nigra
Shell of Amastra nigra
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Order: Stylommatophora
Family: Amastridae
Genus: Amastra
Species:
A. nigra
Binomial name
Amastra nigra
(Newcomb, 1855)
Synonyms
  • Achatinella nigra Newcomb, 1855 superseded combination
  • Achatinella nigra L. Pfeiffer, 1856 junior subjective synonym
  • Amastra (Amastra) nigra (Newcomb, 1855) alternative representation

Amastra nigra is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Amastridae.[1]

Subspecies
  • Amastra humilis moomomiensis Pilsbry & C. M. Cooke, 1914
  • Amastra humilis sepulta Pilsbry & C. M. Cooke, 1914

Description

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The length of the shell attains 17 mm, its diameter 11.2 mm

The dextral shell is globosely acuminate, moderately solid, and composed of 6 whorls. The two lower whorls are prominently inflated, contrasting with the subulate superior whorls. The last two whorls display a rugged surface, characterized by coarse longitudinal striae intersected by irregularly spaced, revolving ridges that form rough cicatrices. The upper whorls are flattened and densely marked with pronounced longitudinal striae. The suture is simple, distinct, and well-impressed.

The aperture is roundly ovate, with a short columella ending in a well-defined lamellar tooth. The shell is a yellowish-white hue, coated with a delicate black epidermis.

The second embryonic whorl is nearly flat-sided, featuring a sculpture of strong, curved riblets and a prominent carina above the suture. The following whorl displays fine ribbing, which is partially effaced at its center. The final, highly globose whorl is distinctly malleated, characterized by flattened facets and irregular, descending spiral ridges.

The spire is brown, while the body whorl, beneath its dull, blackish cuticle, is almost white. The cuticle is irregularly adorned with angular streaks on the spire. The outer lip is reinforced by a prominent rib or a delicate callus on the inner surface. [2]

Distribution

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This species is endemic to Hawaii, occurring on Maui island.

References

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  1. ^ Amastra nigra (Newcomb, 1855)21 December 2024. Retrieved through: World Register of Marine Species.
  2. ^ Hyatt, A. & Pilsbry, H. A. (1910–1911). Manual of conchology, structural and systematic, with illustrations of the species. Ser. 2, Pulmonata. Vol. 21: Achatinellidae (Amastrinae). Philadelphia: Conchological Department, Academy of Natural Sciences. p. 293. Retrieved 3 December 2024.{{cite book}}: CS1 maint: multiple names: authors list (link) Public Domain This article incorporates text from this source, which is in the public domain.
  • Cowie, R. H., Evenhuis, N. L. & Christensen, C. C. (1995). Catalog of the native land and freshwater molluscs of the Hawaiian Islands. Leiden: Backhuys Publishers. p. 106.{{cite book}}: CS1 maint: multiple names: authors list (link)
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