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Key to Irish Chitons
Species Description


Callochiton septemvalvis (Montagu, 1803) [back to the Key] | [next] | [previous]
C. septemvalvis was originally described from a disfigured specimen with seven valves. Montagu believed its missing valve to be a characteristic of an undescribed species of chiton; it was a specimen of a new species, but characterised by other features in normal individuals that have eight valves. (Some authorities have criticised the name ‘septemvalvis‘ as being mis-leading, but as it was the first epithet used to describe a valid species, the name remains valid.)

Length: to 22 mm (up to 14 mm broad)

Tegmentum colour: orange to brick red, often with white markings, or with shades of  green, bright yellow, or bright orange.

Sculpture: smooth and glossy to the naked eye, diagonal ridges set with black dots (the pigment cups of the ‘shell-eyes’ or ocelli); under magnification the valves are sculptured with small granules arranged in quincunx

Girdle: wide (about 1/3 of the animal’s width) and covered in spicules, with a short marginal fringe of spicules. The girdle is coloured yellow or orange with red markings.

Bathymetric range: shallow subtidal to 1000 m (usually from 10-100 m)

Geographic range: uncommon, but distributed on all coasts of Europe from Scandinavia and the Shetland Islands to the Meditteranean and the Red Sea.

Similar species: Tonicella marmorea


Taxonomy and Synonymy:

ORDER: Callochitonida Giribet & Edgecombe, 2020

FAMILY: Callochitonidae Plate, 1901


Callochiton septemvalvis (Montagu, 1803)


List of synonymised names available at:

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