Echiniscus testudo

The species was described by Louis Michel François Doyère in 1840; he placed it in the genus Emydium.[3]

G. Ramazzotti and W. Maucci classified E. filamentos mongoliensis Iharos, 1973[6] as a synonym of E. testudo in 1983; this was followed by other tardigradologists.[1] In 2017, Piotr Gąsiorek and colleagues restored it as a distinct taxon and elevated it to species level: E. mongoliensis.[7]

Gąsiorek and colleagues also classified E. filamentosus Plate, 1888[8] and E. glaber Bartoš, 1937 as junior synonyms of E. testudo.[7]

It is found throughout most of the Palaearctic,[9] and has been recorded in all continents except Antarctica and Australia.[10][11] Most reports are Holarctic.[12] Locations where it has been recorded include: Denmark, Egypt, the Faroe Islands, France, Germany, Greece, Greenland, Israel, Italy, Morocco,[9] Iberia,[13] Mongolia,[14] and China.[10][15]

Doyère based his description off specimens collected in Paris.[3] The neotype designated by Gąsiorek and colleagues was collected in Paris's Montmartre Cemetery.[7] The type localities of the junior synonyms E. bellermanni and E. inermis are both in Germany: the former is Greifswald,[4] and the latter is the Taunus mountains near Frankfurt.[5]

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  Dorsal view, showing its four segmented bands