Knudsen’s Amastra Snail was described in 1895, the species was restricted to a small remnant of native forest at Pu’u ka Pele in the Waimea Canyon area of the island of Kaua’i, Hawaiian Islands.
The author who described the species also mentions some little information about its whereabouts … and the obvious reasons for its extinction.:
“The species is very rare. We dedicate it to Mr. Knudsen, the young naturalist who discovered it. He writes that it is of very limited distribution, being found far up the mountain only in an isolated tract of woodland which escaped the forest fires of twenty years ago. In three days’ diligent search he found only twelve living examples.”
The species was quite large, its shells reached sizes of about 3,3 cm in length.