The stunningly beautiful Sankulirang Mangkalihat karst covers of 1000 square km in East Kalimantan. It is famous for having over 30 caves with prehistoric rock art dating back to 5,000 years ago. However it is less famous for its flora, an issue which a joint project between RBGE and LIPI (Herbarium Bogoriense and Kebun Raya Bogor) is highlighting. Our joint expedition to the limestone hills of the region in late 2016 yielded 7 Begonia species, one of which is a new record and the remaining 6 appear to be new species endemic to the karst system. We are now working on describing these species (including the succulent peltate species illustrated here), and placing them in a phylogenetic and biogeographic context. All species will receive conservation assessments, and their discovery shows how important this area is as a refuge for Indonesian biodiversity.