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The Hawaiian rail (''Porzana sandwichensis''), Hawaiian spotted rail, or Hawaiian crake was a somewhat enigmatic species of diminutive rail that lived on Big Island of Hawaii, but is now extinct. A dark form and a lighter, spotted one are known (see below). ==Taxonomy== Considerable confusion has been created by the existence of two distinct forms. While it cannot be completely excluded that early specimens were collected on another island, only Oahu and Kauai seem possible given the history of the specimens' collection, and only on the latter island is a similar-sized species now known to have once existed. However, the bones from Kauai are in the upper size range of those found of ''sandwichensis'', while the specimens of the lighter form are all of smaller birds. On the Big Island, a smaller species of ''Porzana'' is now known from subfossil bones found on the southwestern slope of Mauna Kea, but this bird was only the size of a Laysan crake; it may have been the bird named ''iao'' or ''iao'', which would place its extinction at a relatively recent date. In addition, there are some bones of a third species, approximately 15% larger than ''P. sandwichensis'', found near Kailua-Kona. The generally accepted theory is that the lighter birds represent immatures, and certainly only such specimens have been described as young birds (the Hanover specimen is labeled as "juvenile"), but since the exact collection localities are not known with sufficient detail, only DNA analysis could resolve this question, particularly since the recovered bone material can also be expected to yield analyzable DNA fragments. At any rate, both light and dark birds are today treated as a single species, with five of the junior synonyms referring to the dark form. However, ''Rallus obscurus'' is something of a mystery as it is generally assumed that at the time of Gmelin's writing, the species was only known from light birds (which were described as ''sandwichensis'' on the preceding page of Gmelin's work), but he seems to have seen a specimen of his ''obscurus'' at the Leverian Museum.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hawaiian rail」の詳細全文を読む スポンサード リンク
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