''Gemmula sibogae'' 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 ...

Turridae Turridae is a taxonomic family name for a number of predatory sea snails, marine gastropod mollusks in the superfamily Conoidea. MolluscaBase (2018). Turridae H. Adams & A. Adams, 1853 (1838). Accessed through: World Register of Marine Specie ...

, the turrids.

Description

The length of the shell varies between 28 mm and 75 mm. The thin shell is broadly fusiform, with an acute, conical

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 ...

and strong, angular

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 ...

. It is whitish, faintly yellowish on the keel, between the nodules. The shell contains 11

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, but the number may be considerably more, as the upper teleoconch whorl seems to be wanting and the shell has the appearance of being not adult. The holotype contains one upper teleoconch whorl (or 2). It is smooth, convex, and followed by nearly another whorl, with rather remote ribs. The subsequent whorls are concave above the keel, with a moderately strong infrasutural keel and 1 or 2 other spirals in the excavation between suture and keel. The infrasutural keel becomes fainter and is scarcely if at all traceable on lower whorls, where on the contrary the number of spirals increases, so that on body whorl of the specimen their number amounts to 6 and two very narrow ones just above the keel. This latter is rather narrow, composed of 3 narrow superficial spirals, more conspicuous between the nodules, perhaps rubbed off on the nodules themselves. Below the keel the body whorl is very convex, but soon contracted and passes into a slender, moderately long

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 ...

. The whole lower part of this whorl is lirate, irregularly on the body, where 2 lirae are stronger, more regularly on the siphonal canal. The total number of these lirae number about 35, but on the base of the tail too faint to be properly counted. Moreover a few narrow intermediate ones occur below periphery, and the whole shell exhibits very fine growth striae. The nodules on the keel are rounded, slightly compressed, not very numerous, 24 on the body whorl. 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 triangular with an angle above and at the keel. The interior of the aperture is white and smooth. The columellar side is enamelled. The thin peristome is broken. Schepman, 1913. The prosobranchia of the Siboga expedition. Part IV -V - VI: Toxoglossa

Distribution

This species occurs off Indonesia; in the Bismarck Sea and off

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

References

External links

Tucker, J.K. 2004 ''Catalog of recent and fossil turrids (Mollusca: Gastropoda)''. Zootaxa 682:1-1295
{{DEFAULTSORT:Gemmula Sibogae sibogae Gastropods described in 1913