Miliusa chantaburiana Damthongdee & Chaowasku, a new species of Annonaceae from SE Thailand, is described and illustrated. It belongs to a clade with campanulate flowers and inner petals that are generally tightly appressed from the base to more or less the midpoint at anthesis. The new species is remarkable in possessing a strongly recurved apex of the inner petals at anthesis and can be principally differentiated from its morphologically closest species, M. pumila Chaowasku and M. filipes Ridl., both from Peninsular Thailand, by the higher number of stamens and carpels per flower and horseshoe-shaped stigmas. Miliusa chantaburiana is also unique in having a 6-base-pair insertion in the plastid matK sequence. A revised key to species in the campanulate-flowered clade in Thailand is given.Citation: Damthongdee A. & Chaowasku T. 2018: Miliusa chantaburiana (Annonaceae), a new species from SE Thailand. – Willdenowia 48: 293–301. doi: https://doi.org/10.3372/wi.48.48208Version of record first published online on 24 August 2018 ahead of inclusion in August 2018 issue.