A comprehensive taxonomic revision of Goniothalamus species (Annonaceae) occurring in Thailand is presented for the first time. Twenty‐five species are recognized, including three that are described as new to science (Goniothalamus aurantiacus from South‐Western Thailand, Goniothalamus maewongensis from Northern Thailand, and Goniothalamus rongklanus from Northern and North‐Eastern Thailand). Several taxonomic and nomenclatural misunderstandings are corrected. The name G. griffithii is shown to be widely misapplied for populations in Northern Thailand, for which the name G. calvicarpus should be applied; ‘true’G. griffithii is restricted to South‐Western Thailand and Myanmar. In addition, the widely used name G. marcanii is shown to be a synonym of G. tamirensis, and the name G. latestigma, previously regarded as a synonym of G. undulatus, is reinstated. Goniothalamus cheliensis is furthermore newly recorded from Thailand. Most species are restricted to Peninsular Thailand and represent a Malesian floristic component. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 156, 355–384.

An extended molecular phylogenetic analysis of Uvaria (Annonaceae) is presented, using maximum parsimony, maximum likelihood and Bayesian methods, based on sequences of four plastid DNA regions (matK, psbA-trnH spacer, rbcL and trnL-F). The additional taxa include the monotypic West African genus Balonga, the monotypic South-East Asian genus Dasoclema and seven Australian representatives of the genus Melodorum. The results indicate that all of these taxa are nested within a well-supported clade otherwise consisting of Uvaria species, indicating that their taxonomic treatment needs to be reassessed. The distinguishing morphological characteristics of the taxa are re-evaluated and interpreted as specialized adaptations of the basic Uvaria structure. The genus Uvaria is accordingly extended following the transfer of these species, necessitating six new nomenclatural combinations and two replacement names.

A comprehensive taxonomic revision of the genus Dasymaschalon (Annonaceae) in Thailand is presented. Twelve species are recognized, including five that are newly described and one new nomenclatural combination, viz. D. acuminatum sp. nov., D. angustifolium sp. nov., D. dasymaschalum , D. echinatum sp. nov., D. filipes , D. glaucum , D. grandiflorum sp. nov., D. lomentaceum , D. macrocalyx , D. obtusipetalum sp. nov., D. sootepense , and D. wallichii comb. nov. Previous taxonomic confusion regarding the relationship between Dasymaschalon and Desmos is discussed. The most significant diagnostic difference between the two genera is the number and arrangement of petals: Dasymaschalon species have only three petals (homologous with the outer whorl of other Annonaceae) that are apically connivent to form an enclosed pollination chamber, whereas Desmos species have two whorls of three petals which are basally constricted and apically free.

Six new species of Friesodielsia (Annonaceae) are described and illustrated, seven species are documented for Thailand for the first time, and Oxymitra fornicata (Roxb.) D. Das var. glabra is raised to species rank as Friesodielsia andamanica. These additions bring the species diversity of Friesodielsia in Thailand to 16 species. A key to the Thai species is provided.

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