Is an endemic subalpine taxon, from Northwest Nelson to Fiordland, has say 200mm tall stems with usually twin flowers to 27mm across; the lower typically with six rows of stalked labellum calli and the upper with four rows. The all-white flowers have a broadly hooded dorsal sepal, calli advancing right down the labellum midlobe (unlike Caladenia) with marginal calli at the midlobe base. The related Tasmanian S. alpina has red buds and 4 – 6 irregular rows of labellum calli.

The labellum is the modified leading petal, which is usually complex, although not in Thelymitra.

The calli (plural of callus) here are the stalks in rows down “the middle of the labellum” usually termed “the disc.”