[2][3][4] This species is similar to C. huegelii in Western Australia but usually has fewer, more brightly-coloured flowers with a wider labellum.

[3][5] In South Australia is can be distinguished from the similar C. reniformis which has more heavily veined leaves and are green on the lower side.

[8] The large gnat orchid occurs in southern Victoria where it grows in coastal scrub and forest.

It is most common and widespread in the south-west of Western Australia where it grows in near-coastal shrubland, woodland and forest between Perth and Israelite Bay.

[2][3][9] Cyrtostylis robusta is listed as "rare" in Tasmania under the Threatened Species Protection Act 1995.