''Daphnella arafurensis'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

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 ...

Raphitomidae Raphitomidae is a family of small to medium-sized sea snails, marine gastropod mollusks in the superfamily Conoidea.Bouchet P. & Rocroi J.-P. (Ed.) (2005). "Classification and nomenclator of gastropod families". ''Malacologia'' 47(1-2). . 39 ...

Description

The length of the shell attains 15 mm, its diameter 4⅓ mm. (Original description) The fusiform shell is whitish, faintly banded with light brown. It is spirally ridged and striated and marked with the flexuous lines of growth. This species is peculiar on account of the absence of longitudinal ribs. The shell contains 7

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. The two 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 ...

are globose, microscopically reticulated, but appearing smooth under an ordinary lens, rather large. The subsequent five are convex, a little constricted beneath the suture, and spirally ridged and striated. The upper whorls have four or five principal lirae, the uppermost falling just beneath the slight constriction, and the others below at equal distances. The whorls are thickened at or immediately under the sutural line with an elevated ridge, and between this and the first lira and in the interstices between the other lirae the surface is finely striated. 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 ...

is elongate, has about thirty-one ridges in addition to the minute interstriation. 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 narrow, contracted anteriorly into a short, broadish

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 is ...

, together equalling almost half the total length of the shell. The columella is perpendicular, curving a little to the left in front, and coated with a very thin callosity. The outer lip is thickened exteriorly, arcuate in the middle, faintly sinuated towards the lower extremity, and rather deeply notched in the slight constriction of the whorl near but not at the suture.
Smith, E.A. 1884. ''Mollusca''. pp. 34–116, 487–508, 657–659, pls 4–7. In, Report on the Zoological Collections made in the Indo-Pacific Ocean during the voyage of the H.M.S. 'Alert ' 1881-2. London : British Museum Trustees, printed by Taylor & Francis

Distribution

This marine species occurs in the Arafura Sea,

Torres Straits The Torres Strait (), also known as Zenadh Kes, is a strait between Australia and the Melanesian island of New Guinea. It is wide at its narrowest extent. To the south is Cape York Peninsula, the northernmost extremity of the Australian mai ...

, Albany Passage; Queensland, Australia.

References

* Hedley, C. 1922. ''A revision of the Australian Turridae.'' Records of the Australian Museum 13(6): 213–359, pls 42–56

External links

* {{DEFAULTSORT:Daphnella Arafurensis arafurensis Gastropods described in 1884 Gastropods of Australia