Caladenia meridionalis, commonly known as the south coast spider orchid, is a species of orchid endemic to the south-west of Western Australia. It is an early-flowering orchid with a single erect, hairy leaf and one or two white flowers with long, drooping sepals and petals.
Caladenia meridionalis is a terrestrial, perennial, deciduous, herb with an underground tuber and a single erect, hairy leaf, long and wide. One or two white to cream-coloured flowers long and wide are borne on a stalk tall. The sepals and petals have dark reddish-brown, drooping, thread-like tips. The sepal is erect, long, wide and the sepals are a similar length but slightly wider. The lateral sepals spread widely near their bases then hang. The petals are long and wide and arranged like the lateral sepals. The labellum is long and wide, white with red stripes, spots and blotches and the tip is curled under. The sides of the labellum have short, irregular serrations and there are six to twelve creamy-yellow, anvil-shaped calli with pink markings, in two rows along the centre. Flowering occurs from July to August.
Caladenia meridionalis was first described in 2001 by Stephen Hopper and Andrew Phillip Brown and the description was published in Nuytsia. The specific epithet (meridionalis) is a Latin words meaning "southern" referring to the distribution of this species on the south coast.
The south coast spider orchid occurs between Windy Harbour and Albany in the Warren biogeographic region where it grows in shrubland in consolidated sand dunes.
Caladenia meridionalis is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife.