This is a species within the Cercopithecus (mona) group, as recognised by Gautier-Hion (2013), who followed Groves (2001, 2005), and includes C. mona, C. lowei, C. campbelli, C. denti, C. wolfi and C. pogonias. There remains a high degree of uncertainty concerning the most valid taxonomic arrangement of this group. More research is needed on the distributional limits of and areas of possible hybridization between its members to resolve the uncertainty.

Although a lack of data on the distributional limits of putative subspecies of C. pogonias complicates an understanding of their taxonomy, following Gautier-Hion (2013), we tentatively identify three subspecies: C. pogonias pogonias, C. p. nigripes and C. p. grayi. A fourth subspecies, C. p. schwarzianus, was recognised by Groves (2001, 2005) but not Gautier-Hion (2013), while Grubb et al. (2003) described it as synonymous with C. p. grayi. Much more research is needed on the taxonomic status of C. pogonias, especially in the region between the Sanaga River (Cameroon), the Ivindo River (Gabon) and the upstream tributaries of the Congo River in southeastern Cameroon. Gautier-Hion et al. (2013) described this vast area as a putative hybrid zone between subspecies, but there have been no in-depth studies to investigate this.

Cercopithecus pogonias is listed as Near Threatened because, although the species has a very large range, it is increasingly hunted for bushmeat and there is ongoing forest loss, especially at the northwestern and southwest edges of its range. It is likely that there has been a decline in the order of 20–25% over the past 27 years. This decline is expected to continue, and so this species almost qualifies as threatened under criterion A2cd.

Cercopithecus pogonias has a large range, estimated to cover about 1,108,230 km² of moist tropical forest and forest-savanna mosaic. It is found in Cameroon, Central African Republic (CAR), Congo, Democratic Republic of Congo (DRC), Equatorial Guinea (including the island of Bioko), Gabon and the Cabinda enclave of Angola. However, both the species and subspecies limits within this area remain poorly understood. Much more research is needed on the distribution and affinities of C. pogonias populations across this region. In particular, we know little about the populations found between the Sanaga River (Cameroon), the Ivindo River (Gabon) and the upstream tributaries of the Congo River in southeastern Cameroon. Gautier-Hion et al. (2013) describe this area as a putative hybrid zone but it is not clear which variants of C. pogonias inhabit this area, and if they are hybridizing. More research is needed.

Hicks (2010) found that the species was abundant in Bili-Uéré, north of the Rubi River up to the border with CAR (Mbomu River). The northern limit of its distribution is probably the limit of high canopy forest to the north, between about 4° and 6° N, although some parts of the historic range are a little further north and are now degraded forest (if the species is still present). As far as is known, the eastern limit is at about 26° E. and then the right (north) bank of the Itimbiri River in DRC and the right (north) bank of the Congo River, down to the forest-savanna limits in Congo. It may overlap or abut with the distribution of Cercopithecus denti, but there is a lack of information from the possible overlap zone (Sarmiento and Kingdon 2013) and Hicks (2010) saw only C. denti in the bushmeat markets between the Uélé and Rubi Rivers (forest identifications could potentially have been confused with the very similar C. denti). To the southwest, it is possible that this species occurs all the way to the Congo estuary where suitable habitat remains and hunting pressure is low.

Historically, this species was found in Cameroon (Takamanda National Park) at about 9.3° E; however, the most recent surveys in Takamanda (Ikfuingei and Kuchambi 2013) and Dimonika Reserve in Congo (Latour 2010) did not record it, so we must assume it is already extirpated or has become extremely rare in this region. Recent surveys across the Cross River region in Nigeria did not record C. pogonias (Imong et al. 2009), so the Cameroon-Nigeria border area is likely the present western limit.

While we tentatively recognise three subspecies, their distributional limits are poorly studied and not well understood, thus complicating an understanding of their conservation status. According to Gautier-Hion et al. (1999) the nominate subspecies, C. p. pogonias, is restricted to Bioko, Equatorial Guinea, with an unnamed subspecies replacing C. p. pogonias on the mainland north of the Sanaga River. However, Groves (2001) reports C. p. pogonias as occurring from the Cross River across the Sanaga River to Río Muni (mainland Equatorial Guinea), and includes Bioko. In the current treatment, C. p. pogonias includes the animals on Bioko (ca 2,000 km²) and on mainland Africa in the moist forest region between Cross River State, Nigeria, and the Sanaga River in Cameroon, which would mark its southeastern distributional limit (Oates 2011)—a total area of over 50,000 km².

According to Groves (2001), C. p. nigripes is found from Rio Muni, Gabon, and Republic of Congo, south to Cabinda, Angola. The western limit—where no river clearly demarcates its distribution—is the forest-savanna boundary in southern Congo.

According to Groves (2001), C. p. grayi ranges from the middle River Sanaga in Cameroon east to the Central African Republic, the inland region of Congo, and, in DRC east of the River Oubangui to about the Itimbiri River, north of the River Congo.

For more details on the different subspecies, see the separate subspecies assessments.

Data on Cercopithecus pogonias abundance are sparse. The species had the lowest biomass of all primates at Lopé in Gabon (Tutin et al. 1997a). Data from well-studied sites range from 9–11 kg/km² to 115 kg/km² and densities of 4–48 individuals/km² (Gautier-Hion 2013), with the lowest densities at the savanna-forest ecotone (Tutin et al. 1997a). The Bioko population is estimated at just 4,500 animals (in 369 km²), giving a rough population density of 12 individuals/km², so at the low end of the scale for the species (Cronin et al. 2015, Cronin, unpublished data 2016). Further details can be found in the subspecies accounts.

Cercopithecus pogonias is found in primary lowland rainforest and submontane rainforest up to around 1,700 m (Bioko). These monkeys are mostly frugivorous: 60–87% of the diet is fruits and seeds; they also eat a smaller proportion of leaves, flowers and insects (Gautier-Hion 2013). Mean group size in an unhunted area of Lopé National Park in Gabon was 12.6, and biomass was 11 kg/km² (Tutin et al. 1997b). Mean group size in nearby Makandé was reported to be 14 individuals (Brugière 1998), but 12.2 (± 3.2) individuals in a subsequent study (Brugière 2005). The taxon is usually found with other monkey species (Gautier-Hion 2013) and prefers the upper strata of the forest above 20–25 m. Group size is 8–20 individuals.

The major direct threats to C. pogonias are hunting and habitat degradation. Humans are the primary predator (Gautier-Hion 2013) and monkeys are eaten locally in villages or traded commercially for consumption in towns and cities. The indirect threats are increasing human populations, agricultural expansion and logging activities, which create easy access routes into previously remote forests. Human populations in the range states of this taxon are growing at roughly 2.7% annually and this rate will not slow down for several decades (UN 2015, World Bank 2017). Road access into once-remote forests—even around protected areas—has increased hugely during the last 20–30 years (Laporte et al. 2007), facilitating hunting and transport of bushmeat to both local markets and distant urban centres (Abernethy et al. 2013, Ziegler et al. 2016).

The species is affected by habitat modification across parts of its range, especially in Cameroon, Equatorial Guinea, Congo, DRC and Cabinda, as intact high forest, in which the species is most abundant, is converted to farmland and “farm bush” (see Tyukavina et al. 2016). Forest loss in the species range is much less evident in Gabon. Forest loss in the most recent year available (2014) was higher than in all previous years (from 2001) in Congo, DRC and Equatorial Guinea, and in Gabon this was true for 2013, followed by 2014 (WRI 2016). Deforestation will greatly increase in the future as industrial agriculture expands, removing the habitat of various forest-obligate species.

This species is hunted illegally for local consumption and sale in urban markets.

Cercopithecus pogonias is listed on Appendix II of CITES, Class B of the EU Wildlife Trade Regulations, and on Class B of the African Convention on the Conservation of Nature and Natural Resources. Nationally, it is on the list of partially protected species in Nigeria (Federal Ministry of Nigeria 2004). Hunting, sale and consumption of primates in Equatorial Guinea were banned by Presidential Decree in October 2007 (Republic of Equatorial Guinea 2007), although no specific taxon is mentioned in that law. In DRC, C. pogonias is on the partially-protected list (may be hunted with a permit) (Enerunga 2006). In Congo, it is on Annex III of the current law (“all animals not on Annexes I or II”), meaning that it can be hunted for food, but only using traditional methods, and not for commerce, transport away from the site where it was hunted (in other words to a different village or other area), and trafficking products of the species on Annex III are strictly prohibited (MEFDD 2011). Similarly, they are on Class C (may be hunted with a permit) in Cameroon and CAR (Central African Republic 1984, MINFOF 2006).

Hunting is banned in all national parks where C. pogonias occurs so, on paper at least, the species is protected in those areas. However, weak application of and poor compliance with the law outside protected areas (and inside some PAs) results in gun-hunting through most of its range. The taxon occurs in many protected areas including three World Heritage Sites: Lopé-Okanda (Gabon), the Sangha Trinational (Cameroon-CAR-Congo) and the Dja Biosphere Reserve (Cameroon).

The species' strongholds (in terms of large areas of suitable habitat and abundance of individuals) are in the forests of Gabon, especially the protected areas, plus the Dzanga-Sangha complex in CAR, the protected areas of southeastern Cameroon, and the national parks of Conkouati-Douli, Nouabalé-Ndoki and Odzala in Congo. Outside protected areas, these monkeys are likely to be increasingly rare, especially in areas with medium-to-high human population density and active logging.