This species was formerly included (unrecognized) within Maxwell's duiker (Philantomba maxwellii), but was described as a separate species in 2010 on the basis of genetic and morphometric characters. Records of Maxwell's duiker from Nigeria, Benin, and Togo are now taken to refer to P. walteri. The species name walteri - after the Belgian zoologist Walter N. Verheyen - is unusual in its use of a given name rather than a surname.

Head and body length: Approximately 66 cm

Shoulder height: Approximately 36-40 cm

Tail length: Approximately 15 cm

Adult weight: 5-7 kg

This small duiker is an overall slate gray color; the belly and chest are paler. There is no dorsal stripe along the spine, and no contrasting markings on the buttocks. The tail is relatively long, dark, and bushy, and is fringed with white. The hair on the nuchal midline (nape of the neck) is reversed, such that the growth pattern is towards the head. The face is strikingly marked with a dark forehead and a pale stripe above each eye; the cheeks are generally the same color as the body. A conspicuous slit in front of each eye is the site of the preorbital glands. Both sexes have small, pointed horns - unlike certain populations of Maxwell's duiker (Philantomba maxwellii), females almost always have horns. In males, the horns are an average of 5 cm long; in females, they are shorter and smaller, 3.5-4.0 cm.

Similar species

• Closely resembles Maxwell's duiker (Philantomba maxwellii). Differences in their physical characters have yet to be firmly established, and the two species are best distinguished by range and genomics.
• Blue duiker (Philantomba monticola) is similarly-sized and -colored. It lacks the bright facial markings of Verheyen's duiker, and often has a distinct horizontal line on the buttocks where the dark back meets the paler thighs.

Gestation period: 120 days.

Litter size: One.

The reproductive biology of Verheyen's duiker has not been studied in depth, but it is likely similar to other Philantomba duikers. Observations from Nigeria indicate that the majority of births occur in the dry season (January to March and August to September).

There is little published information on Verheyen's duiker, but its general biology likely respembles that of other Philantomba duikers. Preliminary dietary information suggests that leaves and stems comprise the bulk of the diet, with bark, fruit/nuts, and roots/tubers also being consumed. In Fazo-Malfakassa National Park (western Togo), camera trap observations were scarce and only occurred in the dry season. In southern Nigeria, Verheyen's duiker is less common in bushmeat markets in the dry season compared to the wet season - potentially because the dry vegetation gives advance warning of hunters approaching.

Verheyen's duiker is native to woodland savannah and forest mosaics in the Dahomey Gap of Togo, Benin, and Nigeria (this habitat separates the western Guinean forest block from the central African rainforests). The limits of the distribution have yet to be clearly defined. The eastern edge of its distribution, and division from Blue duiker (Philantomba monticola), has been suggested to be either the Niger River or Cross River in Nigeria. To the west, the species' range may extend as far as the Volta River in eastern Ghana. The approximate range is depicted in the map below.

IUCN Red List: Data Deficient (2016).

CITES Listing: Not listed, but likely included in Appendix II under Philantomba maxwellii (2024).

Threats: Hunting, habitat loss.

Most of the studied specimens of Verheyen's duiker have been collected in bushmeat markets. In southern Nigeria, the species comprises around 70% of ungulate carcasses for sale, where the average price in 2022 was 7,500-8,000 Nigerian Naira (~$5 USD). No estimate of total population is currently available.