Phorcus atratus (Wood 1828)

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

Description

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 spire is 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 to 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]

Distribution

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

• Cape Verdes
• Canary Islands
• European waters (ERMS scope)
• Senegal

References

• 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.

Phorcus atratus is een slakkensoort uit de familie van de Trochidae.^[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1828 door Wood.