[1][2] It is part of the C. trilobus aggregate, whose members are characterized by a funnel or dish-shaped labellum and an often heart or kidney-shaped solitary leaf.

The single flower is held on a peduncle with a small, slender floral bract; the ovary is pale yellow-green and ribbed.

The lateral sepals are long and filiform (thread-like), often crimson at the base and fading to crystalline pink or white near the tips.

In 2016, Carlos Lehnebach split off 5 new species from C. trilobus: C. confusus, C. obscurus, C. sanctigeorgianus, C. vitreus, and C. walliae.

[2] Corybas trilobus, like its close relatives, primarily inhabits the understories of southern beech forests consisting of Nothofagus.