''Mitromorpha angusta'' is a species of

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

, a marine

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 ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Mitromorphidae Mitromorphidae is a monophyletic family of small to medium-sized sea snails, marine gastropod mollusks in the superfamily Conoidea Conoidea is a Taxonomic rank, superfamily of predatory sea snails, marine (ocean), marine gastropod Mollusc, mo ...

Description

The length of the shell attains 5.7 mm, its diameter 2.1 mm. (Original description) The narrow shell has a fusiform shape. It contains 6

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, including 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 " ...

of 2 smooth convex whorls, with simple suture. The whorls of the

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 ...

are convex, with simple suture. 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 ...

is tapering anteriorly. 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 narrowly oval, scarcely contracted behind, widely open in front, no

siphonal canal The siphonal canal is an anatomical feature of the shells of certain groups of sea snails within the clade Neogastropoda. Some sea marine gastropods have a soft tubular anterior extension of the mantle called a siphon through which water i ...

, only channelled. 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 thin, simple, uniformly convex in profile. There is no distinct sinus posteriorly. The inner lip is slightly thickened on the straight

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 ...

, with two faint plaits or nodules. The colour of the shell is white, with a spiral row of some seven brown spots, showing just above the suture, and winding to the middle of the outer lip.Verco, J.C. 1909. ''Notes on South Australian marine Mollusca with descriptions of new species. Part XII.'' Transactions of the Royal Society of South Australia 33: 293–342

Distribution

This marine 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 Australia and occurs off

South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...

References

* {{DEFAULTSORT:Mitromorpha Angusta angusta Gastropods described in 1909 Gastropods of Australia