The Colobinae are a subfamily of the Old World monkey family that includes 59 species in 10 genera, including the skunk-like black-and-white colobus, the large-nosed proboscis monkey, and the gray langurs. Some classifications split the colobine monkeys into two tribes, while others split them into three groups. Both classifications put the three African genera Colobus, Piliocolobus, and Procolobus in one group; these genera are distinct in that they have stub thumbs (Greek κολοβός kolobós = "docked"). The various Asian genera are placed into another one or two groups. Analysis of mtDNA confirms the Asian species form two distinct groups, one of langurs and the other of the "odd-nosed" species, but suggests the gray langurs are not closely related to either.