Genoplesium rhyoliticum D.L.Jones

Leaf 100–150 mm long; free part 10–15 mm long, ending below flowers. Spike 20–30 mm long, 5–18-flowered. Flowers moderately crowded, semi-erect, 5 × 4 mm, dark purplish black. Dorsal sepal 4.5 × 2 mm, with dark bands; margins glabrous; apex pointed. Lateral sepals obliquely erect, nearly parallel, 5 × 1 mm; base not humped. Petals 4 × 1 mm, with dark bands; margins glabrous or with few hairs; apex sharply pointed. Labellum stiffly hinged, broadly obovate, 3.5 × 1.7 mm, thick, fleshy; margins with coarse hairs to 0.5 mm long. Callus tapered from base, extending to labellum apex.

Highly localised on rhyolite outcrops scattered among tall forest; the orchids grow in shallow, gravelly loam in moss colonies on rock plates and under adjacent shrubs.