Notes on Strobilanthes (Acanthaceae) with capitate inflorescences in Thailand

Twenty-three species of Strobilanthes Blume with capitate inflorescences are enumerated in Thailand. Strobilanthes phengklaii Kladwong & Chantar., a new species from North-eastern Thailand, is described and illustrated. Strobilanthes paniculiformis J.R.I.Wood, S. phyllostachya Kurz and S. squalens S.Moore are new records in Thailand. Strobilanthes kerrii Craib is reinstated, and S. evrardii var. parviflora J.B.Imlay, S. bombycina J.B.Imlay, Hemigraphis hispidula Craib and Sericocalyx thailandicus Bremek. are treated as new synonyms. 19 taxa are lectotypified. A key to species, taxonomic notes and photographs are provided as well as a preliminary conservation assessment and distribution maps.