Abstract : In the last couple of decades numerous studies have looked at intraspecific genetic variation in a many widely distributed species. These studies have revealed hidden diversity and often suggested the presences of multiple species. Furthermore these studies have reignited the age old “species problem” issue, i.e., what is a species and how to delimit it? Here I present work done in my lab on the widely distributed Hanuman langurs. Our morphological, ecological and molecular studies suggest that the so-called Hanuman langurs consist of at least three species. Implications of this study on Hanuman langur taxonomy and on other widely distributed species will also be discussed.