Caladenia lindleyana, commonly known as the Lindley's spider orchid, is a species of orchid endemic to Tasmania. It has a single, hairy leaf and one or two greenish-yellow flowers tinged with red and with thin dark tips on the sepals. Very few plants of this species survive with only one plant, which has not been seen since 1997, protected in a reserve.
Caladenia lindleyana is a terrestrial, perennial, deciduous, herb with an underground tuber and a single narrow, densely hairy leaf, long and wide. One or two flowers wide are borne on a stalk tall. The flowers are greenish-yellow with red markings and the sepals taper to thin, dark, glandular tips. The sepal is erect, long and about wide, and the sepals are long and about wide and spread widely. The petals are narrow lance-shaped, long, about wide, taper to a thin tip and spread widely. The labellum is long and wide, cream-coloured with dark red stripes and blotches, and the tip is dark red and turned under. The sides of the labellum have a few short, blunt teeth and there are four rows of dark red, hockey stick-shaped calli up to long, along the centre of the labellum. Flowering occurs from November to January.
This caladenia was first described in 1871 by Heinrich Reichenbach and given the name Caladenia patersonii var. lindleyana. The description was published in Beitrage zur Systematischen Pflanzenkunde. In 1998, Mark Clements and David Jones raised it to species status. The specific epithet (lindleyana) honours the botanist John Lindley.
Lindley's spider orchid grows in lowland forest and woodland in the central north and northern Midlands of Tasmania.
Only three populations of Caladenia lindleyana are known, two of which are on private land and contain only a few individual plants. The third population is protected in Diprose Lagoon Nature Reserve near Cleveland, but only contains a single plant which has not been seen since 1997. The species is listed as "Critically Endangered" under the Australian Government Environment Protection and Biodiversity Conservation Act 1999 and as "Endangered" under the Tasmanian Government Threatened Species Protection Act 1995. The main threats to the species are accidental damage due to the small population size, land clearing, fertiliser application and inappropriate fire regimes.