Diuris immaculata, commonly known as the little Esperance bee orchid, is a rare species of orchid that is endemic to the south-west of Western Australia. It has between four and six leaves and up to three golden yellow flowers without markings. It is only known from near Esperance.
Diuris immaculata is a tuberous, perennial herb with between four and six linear to lance-shaped leaves long, wide and folded lengthwise. Up to three golden yellow flowers without markings, long and wide are borne on a flowering stem tall. The sepal is egg-shaped, long, wide and curves upwards. The sepals are oblong to egg-shaped with the narrower end towards the base, long, wide, held below the horizontal and parallel to each other. The petals are held above horizontal, egg-shaped to elliptic, long and wide on a green stalk long. The labellum is long, turns slightly downwards and has three lobes. The centre lobe is broadly egg-shaped to wedge-shaped, long and wide. The side lobes are egg-shaped with the narrower end towards the base, long and wide. There are two callus ridges long spreading apart from each other, near the mid-line of the labellum. Flowering occurs from September to November after fire.
Diuris immaculata was first formally described in 2006 by David Jones from a specimen collected north-east of Esperance and the description was published in Australian Orchid Research. The specific epithet (immaculata) is a Latin word meaning "unstained" or "unspotted", referring to the pure yellow colour of the flowers of this orchid.
The little Esperance bee orchid grows in winter-wet areas from north-east of Esperance to the Cape Arid National Park.
Diuris immaculata is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife,