Amastra ultima

Amastra ultima
	Shell of Amastra ultima (holotype)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Order:	Stylommatophora
Family:	Amastridae
Genus:	Amastra
Species:	A. ultima
Binomial name
	Amastra ultima; Pilsbry & C. M. Cooke, 1914
Synonyms
	Amastra (Cyclamastra) ultima Pilsbry & C. M. Cooke, 1914 alternative representation

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

Description

The length of the shell attains 10 mm, its diameter 6.1 mm.

(Original description) The shell resembles Amastra morticina in overall shape but differs by featuring a significantly larger umbilicus and a much weaker columellar lamella.

The shell contains six whorls. The spire is straightly conic, with all whorls convex. The embryonic whorls are smooth, while the remaining whorls exhibit faint, uneven, and irregular growth striae.

The coloration ranges from russet to mars brown. The body whorl is slightly compressed around the umbilicus, which contains a spiral sulcus positioned opposite the columellar lamella.

The aperture is relatively narrow and angular at both ends, with an interior coloration matching the exterior. The outer lip is thin, and the columella is vertical, bearing a very low, oblique lamella that does not extend to the edge, adding a subtle refinement to the shell's structure. ^[2]

Distribution

This species is endemic to Hawaii and occurs on Honolulu Island.

References

^ Amastra ultima Pilsbry & C. M. Cooke, 1914. 1 December 2024. Retrieved through: World Register of Marine Species.
^ Pilsbry, H. A. & Cooke, C. M. (1914–1916). Manual of conchology, structural and systematic, with illustrations of the species. Ser. 2, Pulmonata. Vol. 23: Appendix to Amastridae, Tornatellinidae, Index to vols. XXI-XXIII. pp. i-xi. Philadelphia: Conchological Department, Academy of Natural Sciences. p. 25. Retrieved 27 November 2024.{{cite book}}: CS1 maint: multiple names: authors list (link) 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. vi. Leiden: Backhuys Publishers. p. 107.{{cite book}}: CS1 maint: multiple names: authors list (link)

[WoRMS-1] Amastra ultima Pilsbry & C. M. Cooke, 1914. 1 December 2024. Retrieved through: World Register of Marine Species.

[2] Pilsbry, H. A. & Cooke, C. M. (1914–1916). Manual of conchology, structural and systematic, with illustrations of the species. Ser. 2, Pulmonata. Vol. 23: Appendix to Amastridae, Tornatellinidae, Index to vols. XXI-XXIII. pp. i-xi. Philadelphia: Conchological Department, Academy of Natural Sciences. p. 25. Retrieved 27 November 2024.{{cite book}}: CS1 maint: multiple names: authors list (link) This article incorporates text from this source, which is in the public domain.

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