Thelymitra atronitida, commonly called the black-hooded orchid, is a species of orchid that is endemic to south-eastern Australia. It has a single erect, leathery, leaf and up to eight moderately dark blue, self-pollinating flowers that only open on hot days.
Thelymitra atronitida is a tuberous, perennial herb with a single erect, leathery, channelled, dark green, linear to lance-shaped leaf NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide with a purplish base. Between two and eight moderately dark blue flowers NaNsigfig=1NaNsigfig=1 wide are arranged along a flowering stem NaNsigfig=1NaNsigfig=1 tall. The sepals and petals are NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. The column is pale blue, NaNsigfig=1NaNsigfig=1 long and about 2sigfig=1NaNsigfig=1 wide. The lobe on the top of the anther is glossy black with a yellow inflated tubular, gently curved tip with a notched end. The side lobes curve upwards and have, toothbrush-like tufts of white hairs. Flowering occurs in October and November but the flowers open only on hot days.[1] [2] [3] [4]
Thelymitra atronitida was first formally described in 2000 by Jeff Jeanes and the description was published in Muelleria from a specimen collected near Genoa.[5] The specific epithet (atronitida) is derived from the Latin words ater meaning "black"[6] and nitida meaning "bright", "shining" or "elegant", referring to the colour of the anther lobe.[7]
The black-hooded sun orchid grows in heathy open forest and grasstree plains in eastern New South Wales, far north-eastern Victoria and eastern Tasmania.
This orchid is only known from two locations in New South Wales, where it is classified as "critically endangered" under the Biodiversity Conservation Act 2016.[8] It is only known from five locations in Tasmania and is listed as "endangered" under the Threatened Species Protection Act 1995 in that state.[9]