Notes on Strobilanthes (Acanthaceae) with capitate inflorescences in Thailand.

Twenty-three species of Strobilanthes Blume with capitate inflorescences are enumerated in Thailand. Strobilanthesphengklaii Kladwong & Chantar., a new species from North-eastern Thailand, is described and illustrated. Strobilanthespaniculiformis J.R.I.Wood, S.phyllostachya Kurz and S.squalens S.Moore are new records in Thailand. Strobilantheskerrii Craib is reinstated, and S.evrardiivar.parviflora J.B.Imlay, S.bombycina J.B.Imlay, Hemigraphishispidula Craib and Sericocalyxthailandicus 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.