While the generic name Philantomba has no clear origin, the specific name monticola has been derived from the Latin words montis (mountain) and colo (meaning "I cultivate" or "I inhabit"), in reference to its montane habitat. The common name "blue" refers to one of its typical coat colours. The common name of duiker comes from the Afrikaans duik or Dutch duiker – both mean "diver", which refers to the practice of the animals to frequently dive into vegetation for cover. In 2012, Anne R. Johnston (of the University of Orleans) and colleagues constructed a cladogram of the subfamily Cephalophinae (duiker), that includes the three genera Cephalophus, Philantomba and Sylvicapra, based on mitochondrial analysis. Philantomba was shown to be monophyletic. It is sister to the rest of the subfamily, from which it diverged nearly 8.73 million years ago (in the late Miocene). The blue duiker split from Maxwell's duiker 2.68 to 5.31 million years ago. This cladogram, however, did not include the newly discovered Walter's duiker. Marc Colyn (of the University of Rennes 1) and colleagues, who had discovered this species in 2010, had prepared a similar cladogram (below) that included it. Subspecies As many as 16 subspecies of the blue duiker have been proposed. In 1997, Jonathan Kingdon demarcated seven major populations of the species. In 2001, Groves and Grubb identified the following subspecies, bifurcating them into two groups on the basis of their colouration and geographical occurrence: The grey-legged or northern subspecies P. m. aequatorialis (Matschie, 1892) – The range, bounded by the Congo River on the west, extends from the Democratic Republic of Congo into Uganda, and up to the Nile River. It is also found to the northeast of the Imatong Mountains (South Sudan). P. m. congicus (Lönnberg, 1908) – The range extends from the east of the Cross River across the Ubangi River to the Congo River, till Lisala (Democratic Republic of Congo). It is also found north of the mouth of the Congo River and in Cameroon and Gabon. P. m. lugens (Thomas, 1898) – The range extends from the Southern Highlands of Tanzania till the Malawi border, though it may occur in the Nyika Plateau in northern Malawi. P. m. melanorheus (Gray, 1846) – The type locality is Bioko, Equatorial Guinea. P. m. musculoides (Heller, 1913) – Occurs in eastern Ugandan and Kenyan forests. The range extends as far east as the East African