africa animal arboreal asia biological classification black-and-white colobus cercopithecinae cheek chordate digital object identifier douc genus gestation gray langur haplorrhini herbivory india javan lutung life expectancy lutung mammal mitochondrial dna nilgiri langur old world monkey olive colobus pench national park pig-tailed langur primate proboscis monkey red colobus skunk snub-nosed monkey species surili terrestrial animal weaning wikimedia commons wikispecies