''Mitromorpha incerta'' is a species of

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

, a marine

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Mitromorphidae Mitromorphidae is a monophyletic family of small to medium-sized sea snails, marine gastropod mollusks in the superfamily Conoidea.Bouchet, P. (2011). Mitromorphidae Casey, 1904. In: MolluscaBase (2018). Accessed through: World Register of Marin ...

Description

The length of the shell is 4.1 mm, its diameter 1.6 mm. (Original description) The uniform light brown shell is small, narrow, somewhat solid and has a fusiform shape. It is composed of 5½ slightly convex

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). Whorls in nature File:Photograph and axial plane floral ...

s, with a well impressed suture. The embryonic portion consists of 1½ whorl smooth and slightly swollen from the dorsal aspect, and apparently with an exsert tip. The penultimate and

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. Spires are ...

whorls relatively strongly ornate, with close narrow ribs traversed by a few strong spiral threads. On the penultimate whorl itself there are twelve or thirteen ribs which are broader than the interspaces, and there are about five spiral threads, the median one being the coarsest. The ribs gradually fade out on the

body whorl The body whorl is part of the morphology of the 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. In gastropods In gastropods, the b ...

, but there are numerous (about fifteen) more or less irregular spiral threads, the strongest being situated at about the shoulder. The

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An opt ...

is elongate-ovate, a little less than half the length of the shell, with a very broad anterior canal. The columella is smooth, slightly excavated medially, and with a gentle twist towards the anterior end. 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 ...

is conical. The shell shows three subconvex

s. The suture is shallow. The, whorls are minutely granulated in spiral rows, fifteen in the third whorl.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 to Australia and occurs off Victoria and

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

References

External links

* {{DEFAULTSORT:Mitromorpha Incerta incerta Gastropods described in 1902 Gastropods of Australia