Koilodepas Hassk. (Euphorbiaceae) is a genus of nine accepted species ranging from India (K. calycinum Bedd.) to Southwest China, Indochina, Southeast Asia, West Malesia, and New Guinea (K. homaliifolium Airy Shaw). Two species are widespread on the southeastern Asian mainland and in western Malesia (K. bantamense Hassk. and K. longifolium Hook. f.), one species is present from China to Thailand (K. hainanense (Merr.) Croizat), three others (K. brevipes Merr., K. laevigatum Airy Shaw, K. pectinatum Airy Shaw) are endemic to Borneo, and a new species is found on Sumatra only (K. cordisepalum Welzen & Muzzaz.). The name K. glanduligerum Pax & K. Hoffm. is lectotypified. Typical for the species is the presence of stellately bundled hairs; spicate inflorescences with a single pistillate flower per node basally and more apically tight, globose groups of small staminate flowers per node; and staminate flowers with a broad, short androphore with the typically shaped, sulcate filaments and divergent anthers (K. laevigatum excepted). The species are difficult to distinguish morphologically. Typical characters of the species are found in the leaf margin (serrulate vs. entire), the base of the leaf blade (convex vs. flat), the color of the dried leaves (green or brown), the type of stamens (threadlike filaments vs. sulcate ones), and especially in the calyx and stigmas of the pistillate flowers (sepals free vs. completely united, loose vs. tight around ovary, enlarging in fruit vs. not enlarging in fruit, and degree in which stigmas branch apically).