It has two grass-like leaves and up to five orange-coloured flowers with brown and purple blotches.Diuris semilunulata is a tuberous, perennial herb with two linear leaves, each 150–250 mm (6–10 in) long, 3–4 mm (0.1–0.2 in) wide and folded lengthwise.

The centre lobe is wedge-shaped, 5–7 mm (0.2–0.3 in) wide with a central ridge.

There are two raised callus ridges 3–6 mm (0.1–0.2 in) long near the mid-line of the labellum.

[2][3] Diuris semilunulata was first formally described in 1944 by Pearl Messmer and the description was published in Herman Rupp's book The Orchids of New South Wales.

[4] The late leopard orchid mostly grows in shallow, rocky soil in open forest in the Australian Capital Territy, New South Wales south from Nerriga and possibly Victoria.