Aegista tumida is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.
The diameter of the shell attains 15.5 mm, its height 13.5 mm.
(Original description) This species differs from the type in several key aspects: it is darker in color, has more tumid whorls, a higher spire, and a wider umbilicus. Additionally, the cuticular lamellae are much less pronounced. One specimen exhibits a pale peripheral band, giving the shell a strong resemblance to Aegista oculus <small>(L. Pfeiffer, 1850).</small>
This snail occurs on Honshu Island, Japan.