''Usilla avenacea'' 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 ...

Muricidae Muricidae is a large and varied taxonomic family of small to large predatory sea snails, marine gastropod mollusks, commonly known as murex snails or rock snails. With about 1,600 living species, the Muricidae represent almost 10% of the Neogas ...

, the murex snails or rock snails. MolluscaBase eds. (2023). MolluscaBase. Usilla avenacea (Lesson, 1842). Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=1000272 on 2023-01-17

Description

(Described as ''Vexilla fusconigra'') The shell is abbreviately fusiform, ventricose, solid. The spire is moderately produced, acute, and less than half the length of the shell. The shell contains six

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, convex, furnished with close transverse granular ribs. The suture is impressed. 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 large, ventricose, and marked with coarse, remote, revolving impressed lines, and fine longitudinal striae and wrinkles. The

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 ...

is short and slightly recurved. 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 oblong-ovate. The outer

lip The lips are the visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be ...

is thick, somewhat dilated, and furnished with six or seven intramarginal tubercular teeth, sinuated at its junction with the body whorl. The columella-lip is smooth, flattened, slightly callous above. The colour of the shell is black or brownish-black. The impressed lines on the body-whorl have a light chocolate colour. The lips are purplish-brown. The teeth are white or bluish. Animal. — The foot is oblong, truncated in front and rounded behind. The tentacles taper cylindrically. The eyes are lateral and sessile, at about two-thirds of the length of the tentacles. The siphon is long. Colour of the animal: dark greenisb-slate, and closely punctured with black and white. The tentacles are zoned witb brown. The tips are white. Pease, W. H. (1860). Descriptions of new species of Mollusca from the Sandwich Islands. Proceedings of the Zoological Society of London. 28: 18-36; 141-148

Distribution

This marine species occurs off

French Polynesia )Territorial motto: ( en, "Great Tahiti of the Golden Haze") , anthem = , song_type = Regional anthem , song = " Ia Ora 'O Tahiti Nui" , image_map = French Polynesia on the globe (French Polynesia centered).svg , map_alt = Location of Frenc ...

and

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

References

External links

Lesson R.P. (1842). Mollusques recueillis dans la mer du Sud et l'Océan Atlantique. Revue Zoologique par la Société Cuviérienne. 5: 184-187

Catalogue des mollusques de l'île de la Réunion (Bourbon). Pp. 1-144. In Maillard, L. (Ed.) Notes sur l'Ile de la Réunion. Dentu, Paris

Gould, A. A. (1861). Description of new shells collected by the United States North Pacific Exploring Expedition. Proceedings of the Boston Society of Natural History. 7: 385-389

Smith, E. A. (1872). A list of the species of the genus Planaxis, with descriptions of eleven new species. Annals and Magazine of Natural History. ser. 4, 9: 37-47

Lesson R.P. (1842). Mollusques recueillis dans la mer du Sud et l'Océan Atlantique. Revue Zoologique par la Société Cuviérienne. 5: 184-187

Deshayes, G. P. (1863). Catalogue des mollusques de l'île de la Réunion (Bourbon). Pp. 1-144. In Maillard, L. (Ed.) Notes sur l'Ile de la Réunion. Dentu, Paris
{{DEFAULTSORT:Usilla Avenacea Gastropods described in 1842 avenacea Taxa named by René Lesson