New species and new records of Artabotrys (Annonaceae) from peninsular Thailand.

Two new species of Artabotrys (Annonaceae) are described from peninsular Thailand. Artabotrys longipetalus J.Chen & Eiadthong, sp. nov., is unique among Artabotrys species in Thailand in having linear petals, relatively long flower pedicels and sessile monocarps. Artabotrys insurae J.Chen & Eiadthong, sp. nov., resembles Artabotrys uniflorus (Griff.) Craib, but can be distinguished by its oblique leaf base, flat petal blades, apiculate anther connective apex and the presence of a monocarp stipe. In addition, two new records for the Flora of Thailand are reported, viz. Artabotrys crassifolius Hook.f. & Thomson and Artabotrys pleurocarpus Maingay ex Hook.f. & Thomson; both species are so far only known from peninsular Thailand. A key to the 20 species of Artabotrys in Thailand is provided.