''Tritia incrassata'', common name the thick-lipped dogwhelk, 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 ...

of small

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 ...

Nassariidae The Nassariidae, Nassa mud snails (USA), or dog whelks (UK), are a taxonomic family of small to medium-sized sea snails, marine gastropod mollusks in the clade Neogastropoda. "Dog whelk" also refers to ''Nucella lapillus''. Shell description T ...

, the Nassa mud snails or dog whelks.Marshall, B. (2016). Tritia incrassata (Strøm, 1768). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=876825 on 2016-05-18

Description

The shell up to 15 mm high with rather high

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 a rounded

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 ...

. 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 ...

is small, distinctly cyrtoconoid with 2.5 smooth

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

teleoconch The gastropod shell is part of the body of a gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium storage. Some ...

contains 6-7 convex whorls, with a

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 ...

of regular spiral cords, broader than the interspaces. Its axial folds become distinctly flexuous 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 bordered externally with a strong

varix A varix (pl. varices) is an abnormally dilated vessel with a tortuous course. Varices usually occur in the venous system, but may also occur in arterial or lymphatic vessels. Examples of varices include: * Varicose veins, large tortuous veins usua ...

forming a rim, normally unique - not repeated at the earlier growth stages on the spire. The inner side of the outer lip bears ca. 10 denticles, elongated in the spiral direction. The parietal edge of the aperture forms a very thin, appressed callus, with a distinct adapical denticle, continued into a thicker

columella Lucius Junius Moderatus Columella (; Arabic: , 4 – ) was a prominent writer on agriculture in the Roman Empire. His ' in twelve volumes has been completely preserved and forms an important source on Roman agriculture, together with the wo ...

r callus with a slightly raised edge. The base of the body whorl has a groove delimiting the outer part of 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 ...

. The colour of the shell is extremely variable, with distinct combinations of brown, black, yellowish or orange hues, most often with a paler band on abapical part of spire whorls and periphery of body whorls. Elsewhere it is arranged in bands or in spiral series of blotches, or uniform. The aperture is white with a highly diagnostic black blotch inside the siphonal canal.

Distribution

This species occurs in European waters, throughout the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...

and the Eastern Atlantic Ocean (from Norway to southern Morocco, also off the Canary Is. and the Azores) at depths between the shoreline to ca. 100 m.

References

* Cernohorsky W. O. (1984). ''Systematics of the family Nassariidae (Mollusca: Gastropoda).'' Bulletin of the Auckland Institute and Museum 14: 1–356. * Backeljau, T. (1986). ''Lijst van de recente mariene mollusken van België ist of the recent marine molluscs of Belgium'' Koninklijk Belgisch Instituut voor Natuurwetenschappen: Brussels, Belgium. 106 pp. * Hayward, P.J.; Ryland, J.S. (Ed.) (1990). ''The marine fauna of the British Isles and North-West Europe: 1. Introduction and protozoans to arthropods.'' Clarendon Press: Oxford, UK. . 627 pp * Gofas, S.; Le Renard, J.; Bouchet, P. (2001). Mollusca, in: Costello, M.J. et al. (Ed.) (2001). ''European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification.'' Collection Patrimoines Naturels, 50: pp. 180–213 * Ávila, S.P.; Cardigos, F.; Santos, R.S. (2004). ''D. João de Castro Bank, a shallow water hydrothermal-vent in the Azores: checklist of marine Molluscs''. Arquipélago (Ciénc. Biol. Mar./Life Mar. Sci.) 21A: 75-80 * Muller, Y. (2004). ''Faune et flore du littoral du Nord, du Pas-de-Calais et de la Belgique: inventaire. oastal fauna and flora of the Nord, Pas-de-Calais and Belgium: inventory'. Commission Régionale de Biologie Région Nord Pas-de-Calais: France. 307 pp * BODC (2009). ''Species list from the British Oceanographic Data Centre''

External links

*
Strøm H. (1768). Beskrivelse over Norske Insecter. Andet Stykke. Det Kongelige Norske Videnskabers Selskabs Skrifter, Kjobenhavn. 4: 313-371, pl. 16

Bruguière J.G. (1789-1792). Encyclopédie méthodique ou par ordre de matières. Histoire naturelle des vers, volume 1. Paris: Pancoucke. Pp. i-xviii, 1-344

Lamarck, (J.-B. M.) de. (1822). Histoire naturelle des animaux sans vertèbres. Tome septième. Paris: published by the Author, 711 pp.

Montagu, G. (1803). Testacea Britannica or natural history of British shells, marine, land, and fresh-water, including the most minute: Systematically arranged and embellished with figures. J. White, London, Vol. 1, xxxvii + 291 pp;; Vol. 2, pp. 293–606, pl. 1-16

Pennant, T. (1777). British Zoology, vol. IV. Crustacea. Mollusca. Testacea. London. i-viii, 1-154, pls. 1-93

Payraudeau, B. C. (1826). Catalogue descriptif et méthodique des annelides et des mollusques de l'Ile de Corse; avec huit planches représentant quatre-vingt-huit espèces, dont soixante-huit nouvelles. 218 pp. Paris

Reeve, L. A. (1853-1854). Monograph of the genus Nassa. In: Conchologia Iconica, or, illustrations of the shells of molluscous animals, vol. 9, pls 1-29 and unpaginated text. L. Reeve & Co., London.

Drouët, H. (1858). Mollusques marins des îles Açores. Paris, Baillière. 53 pp., 2 pl

Locard, A. (1886). Prodrome de malacologie française. Catalogue général des mollusques vivants de France. Mollusques marins. Lyon: H. Georg & Paris: Baillière. x + 778 pp

Brusina, S. (1870). Ipsa Chiereghinii Conchylia, ovvero contribuzione pella Malacologia Adriatica desunta dal manoscritto descrizione de' Crostacei, de' Testacei, e de' Pesci che abitano le Lagune e Golfo Veneto, rappresentati in figure, a chiaro-scuro ed a colori dall Abate S. Chiereghini ... illustrata da S. Brusina. Pisa, Biblioteca Malacologica, 280 pp

Forbes E. (1844). Report on the Mollusca and Radiata of the Aegean sea, and on their distribution, considered as bearing on geology. Reports of the British Association for the Advancement of Science for 1843. 130-193

Risso, A. (1826-1827). Histoire naturelle des principales productions de l'Europe Méridionale et particulièrement de celles des environs de Nice et des Alpes Maritimes. Paris, F.G. Levrault. 3(XVI): 1-480, 14 pls

Bucquoy E., Dautzenberg P. & Dollfus G. (1882-1886). Les mollusques marins du Roussillon. Tome Ier. Gastropodes. Paris: Baillière & fils. 570 pp., 66 pls.

Jeffreys, J. G. (1862-1869). British conchology. Vol. 1: pp. cxiv + 341 (1862). Vol. 2: pp. 479 (1864). Vol. 3: pp. 394 (1865). Vol. 4: pp. 487 (1867). Vol. 5: pp. 259 (1869). London, van Voorst.

Galindo, L. A.; Puillandre, N.; Utge, J.; Lozouet, P.; Bouchet, P. (2016). The phylogeny and systematics of the Nassariidae revisited (Gastropoda, Buccinoidea). Molecular Phylogenetics and Evolution. 99: 337-353
{{DEFAULTSORT:Tritia Incrassata incrassata Molluscs described in 1768 Taxa named by Hans Strøm