''Amastra decorticata'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of air-breathing

land snail A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial molluscs, terrestrial gastropod mollusks that have gastropod shell, shel ...

, a

terrestrial Terrestrial refers to things related to land or the planet Earth, as opposed to extraterrestrial. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on o ...

pulmonate Pulmonata or pulmonates is an informal group (previously an order, and before that, a subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group inclu ...

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

in the family

Amastridae Amastridae is a Taxonomy (biology), taxonomic family (biology), family of small, air-breathing, land snails, Terrestrial animal, terrestrial pulmonate gastropod mollusks in the superfamily Pupilloidea.MolluscaBase eds. (2021). MolluscaBase. Amast ...

Description

The length of the shell attains 16 mm, its diameter 8.5 mm The shell is ovate-conic, dextral, and lightly striated with growth lines. Its coloration is chestnut, becoming blackish near the

lip The lips are a horizontal pair of soft appendages attached to the jaws and are the most visible part of the mouth of many animals, including humans. Mammal lips are soft, movable and serve to facilitate the ingestion of food (e.g. sucklin ...

. There are 6 to 6½

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). In nature File:Photograph and axial plane floral diagra ...

s, which are slightly convex, with the first three being polished. The suture is simple and pale. The

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

is weakly colored, with a dirty-blue interior. The

peristome Peristome (from the Greek language, Greek ''peri'', meaning 'around' or 'about', and ''stoma'', 'mouth') is an anatomical feature that surrounds an opening to an organ or structure. Some plants, fungi, and shelled gastropods have peristomes. In mo ...

is thin, blackish on the inside, and only slightly thickened. The columellar fold is thin and delicate. The shell lacks the conspicuously patched appearance typical of ''

Amastra inflata ''Amastra inflata'' is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Amastridae. Description The length of the shell attains 16.5 mm, its diameter 10 mm The shell is imperforate, conic- ...

'' and ''

Amastra elliptica ''Amastra elliptica'' is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Amastridae. Description The length of the shell attains 15 mm, its diameter 8.5 mm The shell is dextral, ovate, a ...

''. However, under magnification, some small, dull streaks may be observed on its otherwise glossy surface, which generally lacks an epidermis in the typical form. Its coloration is a reddish-chestnut of varying intensity, often shading into yellowish tones on the upper part of the body whorl and consistently darker near the lip. The spire is often a deeper purplish-brown. The suture is sometimes marked by a yellowish line, though this feature is not always present. The shell exhibits 2½ whorls in the

protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called " ...

, with the last one being very lightly, minutely, and unevenly striated. Subsequent whorls show rather coarse, low, and uneven wrinkles, making the surface rougher and less glossy compared to A. textilis. The spire's outline contracts slightly near the summit, but the penultimate whorl noticeably bulges, particularly when viewed from the back. The axis is typically perforated, although in some narrower shells, the crevice may be nearly or entirely closed. A few older specimens feature a white callous nodule on the parietal wall, covered thinly by a semi-transparent or dirty-white film that is especially delicate at the outer edge.

Distribution

This species is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

, occurring on

Oahu Oahu (, , sometimes written Oahu) is the third-largest and most populated island of the Hawaiian Islands and of the U.S. state of Hawaii. The state capital, Honolulu, is on Oahu's southeast coast. The island of Oahu and the uninhabited Northwe ...

island.

References

External links

* {{Taxonbar, from=Q131437017 decorticata Gastropods described in 1873