Amastra kaunakakaiensis

The length of the shell attains 14.2 mm, its diameter 7.5 mm. (Original description) The shell is narrowly perforate, oblong-conic, and very thin. It is chestnut brown, glossy, and bare in front of the aperture, while the rest is covered with a delicate russet cuticle that deepens to chestnut and often black on the last half whorl, where it takes on a slight gloss. The shell contains 5¾ whorls. The embryonic whorls are flattened, carinate, and costate, transitioning to moderately convex subsequent whorls with irregular striations. In younger specimens, up to the middle of the fifth whorl, the whorls are sharply angular, but this angle becomes concealed in adults. The aperture is dark inside, lacking both a white lining and a lip-rib. The columellar fold is thin and oblique, with the columellar margin reflected, almost entirely closing the perforation.