Iole

Iole is a genus of bulbuls, songbirds in the family Pycnonotidae. They are native to tropical eastern Asia, from India to China and south through Southeast Asia to northern Indonesia.

It includes the following species:
 * Olive Bulbul, Iole virescens
 * Grey-eyed Bulbul, Iole propinqua
 * Buff-vented Bulbul, Iole olivacea (type species)
 * Sulphur-bellied Bulbul, Iole palwanensis

Some older sources merge this genus into Hypsipetes. But this is neither advisable nor technically correct. The two genera stand well apart, and to phylogenetically justify their merging, the entire "Hypsipetes group" of bulbuls would need to be united in a single genus. That would include Hemixos, Ixos, Microscelis and Tricholestes, and probably also Alophoixus and the monotypic Setornis. The Hook-billed Bulbul (S. criniger) may in fact be the closest living relative of Iole, but altogether the present genus may well be a quite basal lineage of the traditional "Hypsipetes group" of bulbuls, with no particularly close relatives among these.

According to mtDNA NADH dehydrogenase subunits 2 and 3 and nDNA β-fibrinogen intron 7 sequence data Alophoixus is only slightly more distant from Hypsipetes than Iole is, whereas mtDNA 12S rRNA and 16S rRNA sequence data places it actually closer to Hypsipetes than to Iole. And furthermore, the genus name Ixos pre-dates Hypsipetes, and thus would apply to such a thoroughly merged "wastebin taxon".