Two new orchid species and a new section of Bulbophyllum Thouars are described from Madagascar. Bulbophyllum petrae G.A.Fischer, Sieder & P.J.Cribb differs from any other known Madagascan species in the size, form and structure of its flowers. It is placed in its own new section Polyradices G.A.Fischer, Sieder & P.J.Cribb which is distinguished by its tiny habit with densely clustered and bilaterally flattened, unifoliate pseudobulbs, its sessile, one- or two-flowered inflorescence, and its sepals, petals and lip which bear no hairs but the former are finely papillose on the margin and the latter is slightly papillose beneath. It is also distinguished by its lack of spiral vessels in its tissues, a situation very unusual in Madagascan Bulbophyllum. Bulbophyllum jackyi G.A.Fischer, Sieder & P.J.Cribb belongs in section Ploiarium but differs from other species in its unifoliate pseudobulbs, very short inflorescence, broad, erose bracts that enclose the flowers, broadly ovate, papillose fleshy lip and distinctive broadly winged lateral sepals that are papillose within. Notes on their distributions, habitats and conservation status are provided.