The new species Begonia maguniana H.P.Wilson from New Guinea is described. It is endemic to the Central Range of New Guinea at altitudes of c.1700–2300 m and belongs to the IUCN category Least Concern.

Two new species of Begonia sect. Bracteibegonia, B. curvifolia Ardi and B. ocellata Ardi, are described from West Sumatra, Indonesia. The species are endemic to Sumatra and belong to the IUCN category Data Deficient. A modified identification key to all 11 species of Begonia sect. Bracteibegonia in Sumatra is provided.

Four new species of Begonia are described from Northern, Peninsular and Southwestern Thailand. Three belong to Begonia sect. Diploclinium (B. exposita Phutthai & M.Hughes, B. pengchingii Phutthai & M.Hughes and B. pseudosubperfoliata Phutthai & M.Hughes), and one (B. phutthaii M.Hughes) to Begonia sect. Apterobegonia. All four species are karst limestone endemics. The provisional IUCN status of all the new species is ‘Vulnerable’.

Two new species of Begonia (Begoniaceae), Begonia gambutensis Ardi & D.C.Thomas and Begonia siregarii Ardi & D.C.Thomas, are described from material collected on the Indonesian island of Sulawesi. Both species belong to Begonia section Petermannia. A key to the species in the provinces North Sulawesi and Gorontalo is provided.

A new species from Thailand, Begonia bella Phutthai (Begoniaceae), is described and illustrated. It belongs in Begonia sect. Parvibegonia and is a narrow endemic in Phangnga province. Its IUCN category is considered to be ‘Vulnerable’.

Nine new species of Begonia (Begoniaceae), Begonia comestibilis D.C.Thomas & Ardi, B. insueta D.C.Thomas & Ardi, B. lasioura D.C.Thomas & Ardi, B. nobmanniae D.C.Thomas & Ardi, B. prionota D.C.Thomas & Ardi, B. rantemarioensis D.C.Thomas & Ardi, B. sanguineopilosa D.C.Thomas & Ardi, B. torajana D.C.Thomas & Ardi and B. vermeulenii D.C.Thomas, are described from South and West Sulawesi, Indonesia. All belong to Begonia section Petermannia. Proposed conservation categories for these species are Vulnerable (VU) for Begonia comestibilis, B. nobmanniae, B. prionota, B. sanguineopilosa and B. vermeulenii; Least Concern (LC) for B. lasioura, B. rantemarioensis and B. torajana; and Data Deficient (DD) for B. insueta. An identification key to Begonia in South and West Sulawesi (Sulawesi Selatan and Sulawesi Barat) is provided.

A new species of Begonia (Begoniaceae), Begonia gorgonea Tebbitt, is described from Cajamarca Province in northern Peru. This species is allied to a group of Andean species that are currently classified in Begonia sect. Knesebeckia. An identification key to this species group is provided, and the IUCN conservation category of VU D2 is proposed for the new species.

Begonia sect. Diploclinium (Begoniaceae) is revised for the Philippine island of Palawan. Five new species, Begonia acclivis C.Coyle, B. cleopatrae C.Coyle, B. gutierrezii C.Coyle, B. rubiteae M.Hughes and B. wilkiei C.Coyle, are described, giving a total of 10 species, nine of which are endemic. Of the 10 species, two are considered to belong to the IUCN category Endangered, five are Vulnerable, two are Least Concern and one is Data Deficient.

Two new species of Begonia (Begoniaceae), Begonia didyma D.C.Thomas & Ardi and Begonia guttapila D.C.Thomas & Ardi, are described from the Latimojong Mountains, South Sulawesi (Sulawesi Selatan), Indonesia. Both species belong to Begonia sect. Petermannia.

Begonia sect. Petermannia (Begoniaceae) is revised for the Philippine island of Palawan. Three species are recognised, namely Begonia palawanensis Merr. and the newly described B. androturba C.Coyle and B. georgei C.Coyle.

A new species of Begonia (Begoniaceae), B. varipeltata D.C.Thomas, is described from the Indonesian island of Sulawesi. It exhibits peltate leaves, which are rare in Begonia section Petermannia, to which it belongs.

A new species of Begonia (Begoniaceae) is described from Khammouan Province in Laos. The new species, Begonia cladotricha M.Hughes, belongs in Begonia sect. Diploclinium, and is unusual amongst Asian Begonia in having basally branched hairs on all vegetative parts of the plant.

Four new species of Begonia (Begoniaceae) are described from the Indonesian island of Sulawesi. All four species (Begonia chiasmogyna M.Hughes, Begonia macintyreana M.Hughes, Begonia mendumae M.Hughes and Begonia stevei M.Hughes) belong to Begonia section Petermannia, and they increase the number of Begonia species known from the island to 30.

The new species Begonia samhaensis, in section Peltaugustia (Warb.) Barkley, is described from the island of Samha in the Socotra archipelago. It differs from the only other species in the section, B. socotrana Hook.f., in a number of gross morphological characters and is likely to be a relict taxon rather than the result of more recent dispersal and divergence. A revision of sect. Peltaugustia is presented. Detailed surveys have been carried out on both species. The new species has a restricted distribution and a total population of fewer than 1000 individuals, and is recommended to be placed in the IUCN category VU D1, 2. Begonia socotrana has been found in new sites, and is locally common in parts of its range. Its current placing in the IUCN ‘Vulnerable’ category is considered to be unwarranted, and it is recommended that the species should be listed as ‘Least Concern’.