Aphyllorchis periactinantha (Orchidaceae, Neottieae), a new mycoheterotrophic species from peninsular Thailand Amonrat Chantanaorrapint 1 , Sahut Chantanaorrapint 2 1 Faculty of Natural Resources, Prince of Songkla University, Hat Yai, Songkhla 90110, Tailand 2 PSU Herbarium, Division of Biological Science, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, 90110, Tailand Corresponding author: Sahut Chantanaorrapint (sahut.c@psu.ac.th) Academic editor: João Farminhão  |  Received 9 August 2022  |  Accepted 28 November 2022  |  Published 19 December 2022 Citation: Chantanaorrapint A, Chantanaorrapint S (2022) Aphyllorchis periactinantha (Orchidaceae, Neottieae), a new mycoheterotrophic species from peninsular Tailand. PhytoKeys 215: 107–115. https://doi.org/10.3897/ phytokeys.215.91458 Abstract A new orchid species from southern Tailand, Aphyllorchis periactinantha, is described and illustrated. Te novelty is characterized by the subactinomophic fowers, the concave labellum, not divided into hypochile and epichile, the reduced staminodes, the shallowly bilobed stigma and the semicircular rostellum. A key to the species of Aphyllorchis in Tailand is updated. Keywords achlorophyllous orchid, dipterocarp forest, Epidendroideae, peloric fower, Tai-Malay Peninsula, Ton Nga Chang Wildlife Sanctuary Copyright Amonrat Chantanaorrapint & Sahut Chantanaorrapint. This is an open access article distributed under the terms of the Creative Com- mons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. PhytoKeys 215: 107–115 (2022) doi: 10.3897/phytokeys.215.91458 https://phytokeys.pensoft.net RESEARCH ARTICLE Launched to accelerate biodiversity research A peer-reviewed open-access journal