''Bullia callosa'', common name the callused bullia, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

, a marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Nassariidae The Nassariidae, Nassa mud snails (US), or dog whelks (UK) are a taxonomic family of small to medium-sized snails, mostly marine gastropod mollusks in the clade Neogastropoda. These snails have rounded shells with a high spire, an oval ap ...

, the Nassa mud snails or dog whelks.

Description

The length of the shell varies between 18 mm and 50 mm. The shell is elongated and cylindrical. The whole external surface is smooth, shining, of a coffee and milk color. The elongated

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. Spire ...

is pointed. It is composed of six not 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). In nature File:Photograph and axial plane floral diagra ...

s. Each whorl is covered between the sutures with a layer of matter, which assumes at the base a chestnut color. This layer is much thicker upon the

body whorl The body whorl is part of the morphology (biology), morphology of the gastropod shell, 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 ...

, and is continued, enlarging itself, to the left lip, where it forms a large semicircular callosity, of a deep chestnut color, bordered with white. Each of the whorls of the spire is likewise separated from the others by a fawn-colored line, which is delineated a little below each suture. The

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

is ovate, of a pale fawn-color, dilated towards the middle, strongly emarginated at its base. The

columella Lucius Junius Moderatus Columella (, Arabic: ) was a prominent Roman writer on agriculture in the Roman Empire. His in twelve volumes has been completely preserved and forms an important source on Roman agriculture and ancient Roman cuisin ...

is arcuated, callous, fawn-colored and smooth. The callosity of the

is oblique, thick, furrowed, much shorter than the outer lip. From its lower part, a stria stretches out, which is directed obliquely upon the back of the shell, to its termination at the anterior angle of the right lip, which is sharp.Kiener (1840). General species and iconography of recent shells : comprising the Massena Museum, the collection of Lamarck, the collection of the Museum of Natural History, and the recent discoveries of travellers; Boston :W.D. Ticknor,1837
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Distribution

This marine species occurs from

Angola Angola, officially the Republic of Angola, is a country on the west-Central Africa, central coast of Southern Africa. It is the second-largest Portuguese-speaking world, Portuguese-speaking (Lusophone) country in both total area and List of c ...

Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...

References

* Marais J.P. & Kilburn R.N. (2010) Nassariidae. pp. 138–173, in: Marais A.P. & Seccombe A.D. (eds), ''Identification guide to the seashells of South Africa. Volume 1''. Groenkloof: Centre for Molluscan Studies. 376 pp.

External links

* {{Taxonbar, from=Q4996910 Nassariidae Gastropods described in 1828