Nassarius incrassatus

Tritia incrassata
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
(unranked):	clade Caenogastropoda clade Hypsogastropoda clade Neogastropoda
Superfamily:	Buccinoidea
Family:	Nassariidae
Subfamily:	Nassariinae
Genus:	Tritia
Species:	T. incrassata
Binomial name
Tritia incrassata (Ström, 1768)
Synonyms
Buccinum ascanias Bruguière, 1789 Buccinum coccinella Lamarck, 1822 Buccinum incrassatum Strøm, 1768 (original combination) Buccinum lacepedii Payraudeau, 1826 Buccinum macula Montagu, 1803 Buccinum minutum Pennant, 1777 Hinia incrassata (Ström, 1768) Nassa delicata Reeve, 1854 Nassa deshayesii Drouet, 1858 Nassa elongata Bucquoy, Dautzenberg & Dollfus, 1882 Nassa goreensis Maltzan, 1884 Nassa interjecta Locard, 1886 Nassa intermedia Forbes, 1844 Nassa jousseaumi Locard, 1886 Nassa rosacea Reeve, 1854 Nassa saxatilis Brusina, 1870 Nassa senegalensis Maltzan, 1884 Nassa tenella Reeve, 1854 Nassa valliculata Locard, 1886 Nassa varicosa Bucquoy, Dautzenberg & Dollfus, 1882 Nassarius (Hinia) incrassatus (Ström, 1768) Nassarius incrassatus (Strøm, 1768) Planaxis affinis Risso, 1826 Planaxis desmarestiana Risso, 1826 Planaxis rosacea Risso, 1826

Tritia incrassata, common name the thick-lipped dogwhelk, is a species of sea snail, a marine gastropod mollusk in the family Nassariidae, the Nassa mud snails or dog whelks.

The shell up to 15 mm high with rather high spire and a rounded body whorl. The is small, distinctly cyrtoconoid with 2.5 smooth whorls. The teleoconch contains 6-7 convex whorls, with a sculpture of regular spiral cords, broader than the interspaces. Its axial folds become distinctly flexuous on the body whorl. The aperture is bordered externally with a strong varix 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 columellar callus with a slightly raised edge. The base of the body whorl has a groove delimiting the outer part of the siphonal canal.

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.

This species occurs in European waters, throughout the Mediterranean Sea 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.

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