''Mangelia nisga'' 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 ...

Mangeliidae Mangeliidae is a monophyletic family of small to medium-sized, predatory sea snails, marine gastropod mollusks in the superfamily Conoidea. Bouchet, P. (2011). Mangeliidae P. Fischer, 1883. In: MolluscaBase (2016). Accessed through: World Regis ...

.P. Bartsch (1915), Report on the Turton collection of South African marine mollusks, with additional notes on other South African shells contained in the United States National Museum; Bulletin of the United States National Museum v. 91 (1915)

Description

The length of the shell attains 3.1 mm, its diameter 1.5 mm. (Original description) The small shell is yellowish white. The 1½

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 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 small, smooth, forming a very small, well-rounded. The apex is white. The subsequent whorls show a very strong sloping shoulder, which is bounded anteriorly by a strong tuberculated spiral cord. In addition to this cord, the whorls are marked by three additional cords, which decrease in strength successively from the strong cord at the shoulder, to the suture. The space between the strong shoulder and the summit of the shell is marked by a strong spiral thread. The base of 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 marked by a peripheral cord, about as strong as the one adjacent to it posteriorly and two others as strong as this, having the same spacing as those on the spire. The columella is provided with four cords, of which the fourth, which marks the anterior limit of the columella, is as strong as the first, while the two intermediate ones are less strongly developed. In addition to the spiral

sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

, the whorls are marked with rounded, low, quite regularly spaced, axial ribs, of which 10 occur upon the first and second, and 14 upon the body whorl . These ribs render the spiral cords tuberculated at their junction with them. In addition, to these strong axial ribs, the entire surface of the shell, between the sutures ami the anterior half of the base, is marked by numerous, quite regular, closely spaced, axial threads, which are best shown in the spaces between the spiral cords and on the tabulated summit of the whorls. The aperture is rather large, scarcely channeled posteriorly. The outer lip is very thick, rendered denticulate on the outside by the spiral cords. The inner lip and the parietal wall are glazed with a thin callus.

Distribution

This marine species occurs off

Port Alfred A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Ha ...

, South Africa.

References

Tucker, J.K. 2004 ''Catalog of recent and fossil turrids (Mollusca: Gastropoda)''. Zootaxa 682:1-1295.
{{Taxonbar, from=Q48835813 nisga Gastropods described in 1915