Phorcus atratus

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Phorcus atratus
Phorcus atratus 01.JPG
A shell of Phorcus atratus
Scientific classification e
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Clade: Vetigastropoda
Superfamily: Trochoidea
Family: Trochidae
Genus: Phorcus
Species: P. atratus
Binomial name
Phorcus atratus
(Wood, 1828)
  • Monodonta colubrina Gould, A.A., 1849
  • Monodonta tamsi Dunker
  • Monodonta tesselata Deshayes, G.P.
  • Osilinus atratus (Wood, 1828)
  • Osilinus atratus selvagensis Talavera 1978
  • Osilinus atratus trappei Nordsieck, 1974
  • Trochus atratus Wood W., 1828 (original description)
  • Trochus tamsii Dunker in Philippi, 1845

Phorcus atratus is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.[1][2]


The height of the shell varies between 17 mm and 24 mm, its diameter between 16 mm and 19 mm. The solid, imperforate shell has a conical shape. The spireis conical. The apical whorls are eroded, the following dull cinereous or purplish-black, marked with several spiral rows of white spots, or with longitudinal zigzag white stripes. The base of the shell is generally tessellated or striped with white. The shell contains 5 tp 6 whorls. The upper ones are marked with spiral impressed lines in young specimens, and two carinae, the latter giving the body whorl a squarish form. The aperture is oblique. The lip is not much thickened within. The short columella is obsoletely subdentate at its base. Above at the insertion it shows a heavy white callous spread upon the base, invading the umbilicus, and wholly closing it, or leaving only a narrow pit.

This species is quite variable in coloration, the white appearing either in oblique zigzags or in spots. The young are perforate. [3]


This marine species occurs in the following locations:[1]


  1. ^ a b c Gofas, S. (2012). Phorcus atratus (Wood, 1828). Accessed through: World Register of Marine Species at on 2012-11-23
  2. ^ Donald K.M., Preston J., Williams S.T., Reid D.R., Winter D., Alvarez R., Buge B., Hawkins S.J., Templado J. & Spencer H.G. 2012. Phylogenetic relationships elucidate colonization patterns in the intertidal grazers Osilinus Philippi, 1847 and Phorcus Risso, 1826 (Gastropoda: Trochidae) in the northeastern Atlantic Ocean and Mediterranean Sea. Molecular Phylogenetics and Evolution, 62(1): 35–45
  3. ^ Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia (described as Monodonta tamsi)
  • Wood W., 1828: Supplement to the Index Testaceologicus or a catalogue of shells, British and foreign ; London, privately published; pp. VI + 59 + 8 pl
  • Nordsieck F., 1974: Il genere Osilinus Philippi, 1847 nei mari europei ; La Conchiglia 9-10 (67-68): 21-23
  • Talavera F.G., 1978: Moluscos marinos de las Islas Salvajes. In: Contribución al estudio de la historia natural de las Islas Salvajes; * Aula de Cultura de Tenerife p. 119-128, 1 pl.

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