Amastra Obesa
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''Amastra obesa'' 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 ...
s,
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 ...
mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000  extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...
s 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 ...
. ;Subspecies: * ''Amastra obesa aurora'' Pilsbry & C. M. Cooke, 1914 * ''Amastra obesa obesa'' (Newcomb, 1853)


Description

The length of the shell attains 13 mm, its diameter 9.5 mm. The shell is dextral, depressed-conical, and inflated, with a solid structure and pronounced striations. It is covered by a dark umber-colored epidermis. It is composed of five rounded
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. The
apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics) A-Bomb Abomination Absorbing Man Abraxas Abyss Abyss is the name of two characters appearing in Ameri ...
is acute, and the suture is simple yet distinctly defined. 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 ovate and white, with the
columella Lucius Junius Moderatus Columella (, Arabic: ) was a prominent Roman writer on agriculture in the Roman Empire. His in twelve volumes has been completely preserved and forms an important source on Roman agriculture and ancient Roman cuisin ...
featuring a strong, prominent white plait. The outer
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 ...
is simple and slightly thickened on the inner side. The shell is imperforate or faintly rimate, globose with a short, concavely conic
spire A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spire ...
, and relatively thin. It is pale brown beneath a dull chestnut or umber cuticle, which remains intact except near the aperture. The whorls of 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 " ...
, numbering about 2½, are convex and finely striated, with the last one being subtly angular and slightly perforate. The subsequent whorls exhibit coarse, irregular wrinkles, with the
body whorl The body whorl is part of the morphology (biology), morphology of the gastropod shell, shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk ...
rounded at the periphery and faintly adorned with shallow, coarse spiral striations. The aperture is small and oblique, white on the interior. The outer lip features a narrow internal rib. The columella is short, white, and adorned with an obtuse lamella. The entire animal is a sooty black. The upper tentacles are prominently clubbed, while the lower tentacles have light-colored tips. The surface granulations are large and pronounced. The tentacles are longer than the shell. Its movements are notably slow and cautious, exuding a timid demeanor.


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 ...
to Hawai, occurring on
Molokai Molokai or Molokai ( or ; Molokaʻi dialect: Morotaʻi ) is the fifth most populated of the eight major islands that make up the Hawaiian Islands archipelago in the middle of the Pacific Ocean. It is 38 by 10 miles (61 by 16 km) at its g ...
island.


References

*


External links

* {{Taxonbar, from=Q131557042 obesa Gastropods described in 1853