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Amastra

Amastra is a genus of small air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Amastridae.

Like many Hawaiian land snails, species in this genus have adapted to a specific ecological niche and have evolved in relative isolation. They used to thrive in wet or moderately wet forested areas.

Unfortunately, many of the species in this genus have become extinct in recent times or have become critically endangered through habitat loss or, in most cases, predation by Euglandina rosea. This loss is often highlighted as part of the broader biodiversity crisis faced by the Hawaiian Islands.

Some individuals of remaining extant Amastra species were collected for captive breeding programs at the Bishop Museum and Snail Extinction Prevention Program. Reintroductions of some species are currently underway.

Description

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.

Distribution

This genus is endemic to the Hawaiian Islands.

Species

Species within the genus Amastra include:

Taxa inquirenda

  • Amastra amboinensis <small>E. A. Smith, 1873</small>
  • Amastra amicta <small>E. A. Smith, 1873</small>
  • Amastra citrea <small> Sykes, 1896</small>: synonym of Amastra mucronata citrea <small>Sykes, 1896</small> (superseded rank)
  • Amastra lineolata <small>(Newcomb, 1853)</small>
  • Amastra longa <small> Sykes, 1896</small>
  • Amastra peasei <small>E. A. Smith, 1873</small>
  • Amastra seminuda <small>Baldwin, 1906</small>
  • Amastra villosa <small> Sykes, 1896</small>: synonym of Amastra hutchinsonii <small>(Pease, 1862)</small> (junior subjective synonym)

Synonyms

  • Amastra acuta <small>(Swainson, 1828)</small>: synonym of Amastra spirizona <small>(Quoy & Gaimard, 1825)</small> (junior subjective synonym)
  • Amastra anaglypta <small>C. M. Cooke, 1917</small>: synonym of Amastra sericea anaglypta <small>C. M. Cooke, 1917</small> (superseded rank)
  • Amastra bigener <small>Hyatt, 1911</small>: synonym of Amastra affinis <small>(Newcomb, 1854)</small> (junior subjective synonym)
  • Amastra carinata <small>Gulick, 1873</small>: synonym of Amastra agglutinans <small>(Newcomb, 1854)</small> (junior subjective synonym)
  • Amastra citrea <small>Sykes, 1896</small>: synonym of Amastra mucronata citrea <small>Sykes, 1896</small> (superseded rank)
  • Amastra conicospira <small>E. A. Smith, 1873</small>: synonym of Amastra cylindrica (Newcomb, 1854) (junior subjective synonym)
  • Amastra cookei <small>Hyatt & Pilsbry, 1911</small>: synonym of Amastra textilis <small>(Quoy & Gaimard, 1825)</small> (junior subjective synonym)
  • Amastra deshaysii <small>(Morelet, 1857)</small>: synonym of Amastra assimilis <small>(Newcomb, 1854)</small> (junior subjective synonym)
  • Amastra frosti <small>Ancey, 1892</small>: synonym of Amastra micans <small>(L. Pfeiffer, 1859)</small> (junior subjective synonym)
  • Amastra heliciformis <small>Ancey, 1890</small>: synonym of Tropidoptera heliciformis <small>(Ancey, 1890)</small> (superseded combination)
  • Amastra henshawi <small>Baldwin, 1903</small>: synonym of Amastra flavescens henshawi <small>Baldwin, 1903</small> (superseded rank)
  • Amastra kuhnsi <small>Cooke, 1908</small>: synonym of Laminella kuhnsi <small>(C. M. Cooke, 1908)</small> (original combination)
  • Amastra nigrolabris <small>E. A. Smith, 1873</small>: synonym of Amastra spirizona nigrolabris <small>E. A. Smith, 1873</small> (superseded rank)
  • Amastra rustica <small>Gulick, 1873</small>: synonym of Amastra affinis <small>(Newcomb, 1854)</small> (junior subjective synonym)
  • Amastra saxicola <small>Baldwin, 1903</small>: synonym of Amastra flavescens saxicola <small>Baldwin, 1903</small> (superseded combination)
  • Amastra simularis <small>W. D. Hartman, 1888</small>: synonym of Amastra mucronata <small>(Newcomb, 1853)</small> (junior subjective synonym)
  • Amastra villosa <small>Sykes, 1896</small>: synonym of Amastra hutchinsonii <small>(Pease, 1862)</small> (junior subjective synonym

References

  • Bank, R. A. (2017). Classification of the Recent terrestrial Gastropoda of the World. Last update: July 16, 2017

External links