Acianthus amplexicaulis, is a species of flowering plant in the orchid family Orchidaceae and is native to eastern Australia and New Caledonia.

[3][4] The species was first described in 1891 by Frederick Manson Bailey who gave it the name Microstylis amplexicaulis in the "Botany Bulletin" of the "Department of Agriculture, Queensland" from specimens collected in the "scrubs of Eudlo Creek in 1891".

[5] In 1903, Robert Allen Rolfe transferred the species to Acianthus as A. amplexicaulis in The Orchid Review, a name accepted by Plants of the World Online and in New Caledonia.

[3] In 2017, Stephanie Pimm Lyon, Mark Clements and David Jones transferred the species to the genus Stigmatodactylus as S. amplexicaulis, a name accepted by the Australian Plant Census.

[7] Acianthus amplexicaulis grows in moist coastal scrub in littoral rainforest from north-eastern Queensland to Wyrrabalong National Park in New South Wales, and in New Caledonia.