Caladenia sanguinea, commonly known as red spider orchid or crimson daddy long-legs, is a species of orchid endemic to South Australia. It has a single sparsely hairy leaf and one or two dark red flowers with long, thin sepals and petals.
Caladenia sanguinea is a terrestrial, perennial, deciduous, herb with an underground tuber and a single sparsely hairy leaf, long and wide. One or two dark red flowers wide are borne on a stalk tall. The sepals and petals have long, thin, thread-like tips. The sepal is long and about wide. The sepals are long and about wide and spread apart from each other, curving downwards. The petals are long and about wide and arranged like the lateral sepals. The labellum is long, about wide and white with dark red markings. The sides of the labellum have short, broad teeth, the tip of the labellum is curled under and there are two rows of red, anvil-shaped calli along the mid-line of the labellum. Flowering occurs from August to October.
Caladenia sanguinea was first described in 1999 by David Jones from a specimen collected on Kangaroo Island and the description was published in The Orchadian. The specific epithet (sanguinea) is a Latin word meaning "blood", "bloody" or "blood-red".
Crimson daddy long-legs is only found in the Eyre Peninsula, Yorke Peninsula and Kangaroo Island botanical regions of South Australia where it grows in mallee woodland and heath.
Caladenia sanguinea is classified as "rare" in South Australia.