It has a single erect, leathery, leaf and up to eight moderately dark blue, self-pollinating flowers that only open on hot days.

The lobe on the top of the anther is glossy black with a yellow inflated tubular, gently curved tip with a notched end.

[2][3][4][5] Thelymitra atronitida was first formally described in 2000 by Jeff Jeanes and the description was published in Muelleria[4] from a specimen collected near Genoa.

[2][5][8] 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.

[9] It is only known from five locations in Tasmania and is listed as "endangered" under the Threatened Species Protection Act 1995 in that state.