Grangeville Prong-gilled Mayfly (Paraleptophlebia traverae)
This species was described in 1999.
The Grangeville Prong-gilled Mayfly is known from only a single specimen that was collected in the 1930s in Grangeville, the largest city in Idaho County, Idaho, USA.
The species is very likely extinct.
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edited: 31.10.2017