The Japanese River Otter inhabited the rivers on the islands of Honshu, Kyushu and Shikoku in Japan; it was formerly thought to be a subspecies of the Eurasian River Otter (Lutra lutra (L.)).
The species was last seen in 1979 and is now considered extinct.
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edited: 01.08.2022
This subspecies of the Eurasian River Otter (Lutra lutra (L.)) was apparently restricted to the island of Hokkaido, Japan.
The taxonomic status of the otter forms that are known from Japan is somewhat confusing, those forms that are (or were) found on the islands of Honshu, Kyushu and Shikoku are currently considered a distinct, endemic species: Japanese River Otter (Lutra nippon Imaizumi & Yoshiyuki).
The Hokkaido River Otter was last seen during the 1950s and is now extinct.
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edited: 01.08.2022
Sardinian Otter (Sardolutra ichnusae)
The Sardinian Otter is of late Pleistocene- to early Holocene age and thus will be briefly mentioned here in this blog.
The species was rather small and probably inhabited marine habitats, very much like the recent Marine Otter (Lontra felina (Molina)), which is found along the coast of southwestern South America. [1]
The Sardinian Otter disappeared at the Pleistocene/Holocene border, and may have survived to about 7000 BC.
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References:
[1] G. F. Willemsen: A revision of the Pliocene and Quaternary Lutrinae from Europe. Scripta Geologica 101. 1992
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edited: 16.04.2019