The plant below with red flowers was seen in the Singapore Botanical Gardens with the label "Dasymaschalon blumei" on it. Since Dasymaschalon blumei is a synonym of Dasymaschalon dasymaschalum according to the Plant List website, I assume that it is the same species as the one above found in the wild.
The identity of this plant is not conclusive. In the publication by Wang et. al. , there was a picture of the fruit of Dasymaschalon dasymaschalum (page 547) which was more elongated than the one seen in the above picture. In another publication by the same author 3 years later , the same picture was labelled as Dasymaschalon glaucum. There was a picture of the flower and fruit in the later article (pages 255 and 259) which resembled the yellow-flower version above.
 Wang, J., Chalermglin, P. & Saunders, R.M.K. 2009. The genus Dasymaschalon (Annonaceae) in Thailand. Syst. Bot. 34: 252-265. | Read Abstract |
 Wang, J., Thomas, D.C., Su, Y.C.F., Meinke, S., Chatrou, L.W. & Saunders, R.M.K. 2012. A plastid DNA phylogeny of Dasymaschalon (Annonaceae) and allied genera: Evidence for generic non-monophyly and the parallel evolutionary loss of inner petals. Taxon: 545-558. | Read Abstract |