With orbicular leaves 12-20 x 12-20 mm, light green with visible veins above, silvery green beneath, apiculate.
Arising about halfway along the petiole below the leaf lamina but sitting above. Most parts dark red, 25-30 mm long, 10-14 mm wide. Dorsal sepal hooded over most of the labellum, dark red mottled green, lighter and striate towards the base. Lateral sepals erect to spreading, 30 mm long. Petals erect to spreading, 10-15mm long. Labellum midlobe cream to pale yellow in the centre, margins incurved, irregular to toothed, with a deep central groove.
October - November.
Shrublands. Campbell Island, Chatham Islands and isolated locations in the lower North and South Islands.
Sparse. Data Deficient.
Named for the prominent ridges on the dorsal sepal.
Easily recognized by its ball shaped flower and mottled maroon dorsal sepal and outer labellum.