Apex. Shape: distinctly convex.
Spire. Height: 1.7–1.9 mm. Width: 1.4–1.6 mm. Number of whorls: 3 7/8–4 1/4. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: distinctly convex. Umbilicus: completely closed by tuba.
Constriction. Parietal teeth: none. Basal teeth: none.
Tuba. Coiling direction: type 3 and aperture visible in left lateral view. Tuba whorl length in proportion to spire last whorl: ca. 1/2–5/8. Proportion of tuba that attaches to spire: whole.
Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part.
Spiral lines. Thick lines: absent. Thin lines: present.
Radial ribs. Rib density: 6–7 ribs per mm. Rib intensity: thin. Shape: straight. Inclination: orthoclin.
Least Concern. Gua Taat is located in a prioritised protected National Park with good forest cover.
Holotype: BOR 5644(1). Paratypes: BOR 5536(>10), V 8802(1), V 8885(>10).
The general shell form of Plectostoma whitteni is similar to Plectostoma tonkinianum. There is no genetic information for Plectostoma tonkinianum, but Plectostoma whitteni is genetically closer to Plectostoma tohchinyawi than to any of the other 18 species. Nevertheless, Plectostomawhitteni is considered a distinct species as compared to Plectostoma tonkinianum and Plectostomatohchinyawi because of the lack of constriction teeth.
Type locality. Gua Taat, Tasik Kenyir (4°51'3"N, 102°43'21"E).
Distribution range. This species only occurs in Gua Taat, Tasik Kenyir (Figure 18A).