Caladenia septuosa, commonly known as the Koppio spider orchid, is a plant in the orchid family Orchidaceae and is endemic to South Australia. It is a ground orchid with a single erect, sparsely hairy leaf and usually only one greenish-cream flower with red stripes along the sepals and petals.
Caladenia septuosa is a terrestrial, perennial, deciduous, herb with an underground tuber and a single erect, sparsely hairy leaf. The leaf is long, wide and dull green. Usually only a single greenish-cream flower across is borne on a spike tall. The sepals, but not the petals, have brown, club-like glandular tips long. The sepal is long, wide and curves forward. The sepals are long and wide, spread apart and curve downwards. The petals are long, about wide and arranged like the lateral sepals. The labellum is long and wide, green and white with a dark red tip. The sides of the labellum turn upwards and have three or four pairs of thin green teeth up to long, and the tip curves downwards. There are four or six rows of dark red calli up to long, along the labellum mid-line. Flowering occurs from September to October.
Caladenia septuosa was first formally described in 1991 by David Jones and the description was published in Australian Orchid Research. The specific epithet (septuosa) is a Latin word meaning "obscure" referring to the small lateral lobes on the labellum.
The Koppio spider orchid is endemic to the Eyre Peninsula where it grows in woodland.
Caladenia septuosa is locally common and conserved in reserves.