Everettia corrugata williamsi Liew, Schilthuizen & Vermeulen 2009  

Shell medium-sized, rather thin, greenish brown, moderately to distinctly elevated, outer whorls slightly shouldered below the suture. Periphery rounded. Above the periphery, shell with a silky lustre, regularly and densely placed, distinct radial threads and cut by widely spaced spiral grooves. Strong corrugation just below the suture. Below the periphery, shell has very fine spiral grooves (more conspicuous than in Everettia corrugata corrugata). Height up to 11.3 mm; width up to 18.3 mm; diameter of the first three whorls 1.2–1.4, 0.9–1.1, and 1.6–1.8 mm, respectively; number of whorls up to five; height aperture up to 7.7 mm; width aperture up to 9.8 mm. Animal head uniform black or grey and extended backward to the end of mantle and downward to the foot-fringe. A grey smear covers large parts of the animal and extends to the end of the tail. The mantle is covered with sparsely distributed bright spots. These bright spots become denser and are agglomerated with the black spots at the last half whorl.