''Ischnochiton oniscus'', the dwarf chiton, is a small

polyplacophoran Chitons () are marine (ocean), marine molluscs of varying size in the class (biology), class Polyplacophora (), formerly known as Amphineura. About 940 Extant taxon, extant and 430 fossil species are recognized. They are also sometimes known ...

mollusc 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 esti ...

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 ...

Ischnochitonidae Ischnochitonidae is a family of polyplacophoran mollusc belonging to the superfamily Chitonoidea. MolluscaBase eds. (2022). MolluscaBase. Ischnochitonidae Dall, 1889. Accessed through: World Register of Marine Species at: https://www.marinespec ...

, endemic to the coast of southern Africa.

Description

This is the smallest chiton species in southern Africa, reaching an average length of no more than 10 mm. It displays a wide variety of colours and patterns, but is most often white. The

valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings ...

s bear fine pits which are often arranged in rows; radiating ridges are absent. The tiny scales covering the narrow girdle appear smooth to the naked eye but show minute ridges under the microscope.

Distribution and habitat

''Ischnochiton oniscus'' occurs along the coasts of southern Africa, from Saint Helena Bay on the west coast of

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

to Maputo Bay in southern

Mozambique Mozambique (), officially the Republic of Mozambique ( pt, Moçambique or , ; ny, Mozambiki; sw, Msumbiji; ts, Muzambhiki), is a country located in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi ...

. Small groups can be found on the underside of rocks in sandy pools.

References

Ischnochitonidae Molluscs of Africa Chitons described in 1847 {{chiton-stub