Two new species of Xylopia (Annonaceae) from peninsular Thailand

Two previously undescribed species of Xylopia are documented from southern Thailand. Xylopia niyomdhamii is known from a small peat swamp area in Narathiwat Province. Xylopia microcalyx is restricted to the limestone region extending from Chumphon south to Trang and Phatthalung Provinces, an area with many other endemic Annonaceae species. We found that X. malayana s.s., although previously reported, is not present in the Thai flora. A key to X. malayana s.s. and the Thai species of Xylopia is presented to summarize our taxonomic changes.