Caladenia rileyi, commonly known as the Gillenbah spider orchid, is a plant in the orchid family Orchidaceae and is endemic to New South Wales. It is a ground orchid with a single leaf and a single yellowish-green and red flower.
Caladenia rileyi is a terrestrial, perennial, deciduous, herb with an underground tuber and a single leaf, long and wide. A single yellowish-green and red flower is borne on a spike tall. The sepals and petals have thick, brownish, club-like glandular tips long. The sepal is erect, long and wide. The sepals are long, wide and are parallel to each other and held below horizontal. The petals are long, about wide and also turned slightly downwards. The labellum is long and wide and greenish-white with a dark red tip. The sides of the labellum turn upwards and have between four and six teeth up to long. The tip of the labellum curls downwards and there are four rows of crowded calli up to long, along its mid-line. Flowering occurs from September to October.
Caladenia rileyi was first formally described in 1997 by David Jones and the description was published in The Orchadian from a specimen collected in the Gillenbah State Forest near Narrandera.
The Gillenbah spider orchid grows in Callitris woodland between Narrandera and Jerilderie on the south-west slopes of New South Wales.