The World's 25 Most Endangered Primates
# The World's 25 Most Endangered Primates

The World's 25 Most Endangered Primates is a list of highly endangered primate species selected and published by the International Union for Conservation of Nature (IUCN) Species Survival Commission (SSC) Primate Specialist Group (PSG), the International Primatological Society (IPS), Global Wildlife Conservation (GWC), and Bristol Zoological Society (BZS). The IUCN/SSC PSG worked with Conservation International (CI) to start the list in 2000, but in 2002, during the 19th Congress of the International Primatological Society, primatologists reviewed and debated the list, resulting in the 2002–2004 revision and the endorsement of the IPS. The publication was a joint project between the three conservation organizations until the 2012–2014 list when BZS was added as a publisher. The 2018–2020 list was the first time Conservation International was not among the publishers, replaced instead by GWC. The list has been revised every two years following the biannual Congress of the IPS. Starting with the 2004–2006 report, the title changed to "Primates in Peril: The World's 25 Most Endangered Primates". That same year, the list began to provide information about each species, including their conservation status and the threats they face in the wild. The species text is written in collaboration with experts from the field, with 60 people contributing to the 2006–2008 report and 85 people contributing to the 2008–2010 report. The 2004–2006 and 2006–2008 reports were published in the IUCN/SSC PSG journal Primate Conservation,, since then they have been published as independent publications.

The 25 species on the 2018–2020 list are distributed between 32 countries. The country with the most species on the list is Madagascar with five species, Indonesia, Brazil, Ghana, and Cote d'Ivoire each have three. The list is broken into four distinct regions: the island of Madagascar, the continent of Africa, the continent of Asia including the islands of Indonesia, and the Neotropics (Central and South America).

The purpose of the list, according to Russell Mittermeier, the president of CI, is "to highlight those [primate species] that are most at risk, to attract the attention of the public, to stimulate national governments to do more, and especially to find the resources to implement desperately needed conservation measures." Species are selected for the list based on two primary reasons: extremely small population sizes and very rapid drops in numbers. These reasons are heavily influenced by habitat loss and hunting, the two greatest threats primates face. More specifically, threats listed in the report include deforestation due to slash-and-burn agriculture, clearing for pasture or farmland, charcoal production, firewood production, illegal logging, selective logging, mining, land development, and cash crop production; forest fragmentation; small population sizes; live capture for the exotic pet trade; and hunting for bushmeat and traditional medicine. Twelve species were dropped for the 2018–2020 list, Mittermeier notes this was not because their situation has improved but instead to focus attention on other species that are also have "bleak prospects for their survival.

## Key

Key for column headings :

| Species | Common and scientific name of the species, including a picture if available |
| - | - |
| Years listed | Years the species has been included in the IUCN's list of the "Top 25 Most Endangered Primates" |
| Location(s) | Countries in which it is found |
| Estimated population | Latest population estimate from the IUCN |
| IUCN status | Conservation status of the species, per the IUCN as of the date of the latest list publication |
| Threats | A list of threats facing the species; used by the IUCN in assessing conservation status |

## Current list

The World's 25 Most Endangered Primates, 2018–2020: Madagascar :

| Species | Years listed | Location(s) | Estimated population | IUCN status | Threats |
| - | - | - | - | - | - |
| Bemanasy mouse lemur Microcebus manitatra | 2018 | Madagascar | unknown | Critically Endangered | loss of habitat (agricultural encroachment) |
| Hapalemur alaotrensis Lac Alaotra bamboo lemur Hapalemur alaotrensis | 2000 2014 2016 2018 | Madagascar | 2,500 (2018 estimate) | Critically Endangered | loss of habitat (agricultural encroachment, burning of marshlands [to create rice paddies, catch fish, and for cattle grazing] hunting (bushmeat) live capture (local pet trade) |
| James' sportive lemur Lepilemur jamesorum | 2016 2018 | Madagascar | 1,386 (2010 estimate) | Critically Endangered | habitat loss (shifting agriculture) hunting (bushmeat) live capture (pet trade) |
| Indri indri Indri Indri indri | 2012 2018 | Madagascar | unknown | Critically Endangered | loss of habitat (slash-and-burn agriculture, firewood) hunting (bushmeat, skins) |
| Daubentonia madagascariensis Aye-aye Daubentonia madagascariensis | 2016 2018 | Madagascar | unknown | Endangered | habitat loss (selective logging for local use [boats, houses, coffins], agricultural encroachment, fire) hunting (pests, local taboos, bushmeat) |

The World's 25 Most Endangered Primates, 2012–2014: Africa :

| Species | Years listed | Location(s) | Estimated population | IUCN status | Threats |
| - | - | - | - | - | - |
| Rondo dwarf galago Galagoides rondoensis | 2006 2008 2010 2012 | Tanzania | unknown | Critically Endangered | very small range habitat loss and fragmentation (agricultural encroachment, charcoal production, logging) |
| Cercopithecus roloway Roloway monkey Cercopithecus roloway | 2002 2006 2008 2010 2012 | Côte d'Ivoire Ghana | unknown | Endangered | hunting (bushmeat) habitat loss and fragmentation (agricultural encroachment, charcoal production, logging) |
| Tana River red colobus Procolobus rufomitratus | 2002 2004 2006 2008 2012 | Kenya | 1,100–1,300 | Endangered | hunting (bushmeat) habitat loss and fragmentation (agricultural encroachment, fire, firewood, selective logging for local use [houses, canoes]) habitat degradation (livestock, dam construction, irrigation projects) parasitic infection of isolated populations |
| Piliocolobus pennantii pennantii Bioko red colobus Piliocolobus pennantii pennantii | 2004 2006 2010 2012 | Equatorial Guinea (Bioko Island) | fewer than 5,000 | Endangered | habitat degradation hunting (bushmeat) small range |
| Gorilla beringei graueri Eastern lowland gorilla Gorilla beringei graueri | 2010 2012 | Democratic Republic of the Congo | 5,000 | Critically Endangered | habitat loss and fragmentation (agricultural encroachment, pastoral farming, illegal mining, charcoal production, wood and bamboo harvesting) hunting (bushmeat, infant capture) |

The World's 25 Most Endangered Primates, 2012–2014: Asia :

| Species | Years listed | Location(s) | Estimated population | IUCN status | Threats |
| - | - | - | - | - | - |
| Nycticebus javanicus Javan slow loris Nycticebus javanicus | 2008 2010 2012 | Indonesia (Java) | unknown | Critically Endangered | live capture (pet trade [intense]) hunting (traditional medicine [intense]) habitat loss (agriculture, development activities [roads], human disturbance) |
| Pig-tailed langur Simias concolor | 2002 2004 2006 2008 2010 2012 | Indonesia (Mentawai Islands) | 700–3,347 | Critically Endangered | habitat loss (human encroachment, product extraction, commercial logging, conversion to cash crops and oil palm plantations) hunting (bushmeat) live capture (pet trade) |
| Trachypithecus delacouri Delacour's langur Trachypithecus delacouri | 2000 2002 2004 2006 2008 2010 2012 | Vietnam | fewer than 250 | Critically Endangered | habitat fragmentation hunting (bushmeat, traditional medicine) |
| Golden-headed langur Trachypithecus poliocephalus | 2000 2002 2004 2006 2008 2010 2012 | Vietnam | 60–70 | Critically Endangered | habitat fragmentation (human encroachment, development for tourism) hunting (bushmeat, traditional medicine) |
| Western purple-faced langur Semnopithecus vetulus nestor | 2004 2006 2008 2010 2012 | Sri Lanka | unknown | Critically Endangered | habitat loss and fragmentation (urbanization, agricultural encroachment) dependent on gardens for survival live capture (pet trade) hunting (pests) other human factors (electrocution [power lines], road kill, dog attacks) |
| Grey-shanked douc Pygathrix cinerea | 2000 2002 2004 2006 2008 2010 2012 | Vietnam | 600–700 | Critically Endangered | restricted range habitat loss and fragmentation (agricultural encroachment, illegal logging, firewood) hunting (bushmeat, traditional medicine) live capture (pet trade) |
| Rhinopithecus avunculus Tonkin snub-nosed monkey Rhinopithecus avunculus | 2000 2002 2004 2006 2008 2010 2012 | Vietnam | 200–250 | Critically Endangered | habitat loss and fragmentation (logging, firewood, roads) hunting (bushmeat, traditional medicine) |
| Eastern black crested gibbon Nomascus nasutus | 2008 2010 2012 | China Vietnam | around 110 | Critically Endangered | habitat loss, fragmentation, and disturbance (agricultural encroachment, pastoral farming, firewood, charcoal production) hunting (bushmeat) |
| Pygmy tarsier Tarsius pumilus | 2012 | Indonesia (Sulawesi) | unknown | Data deficient | habitat loss (human encroachment) |

The World's 25 Most Endangered Primates, 2012–2014: Neotropics :

| Species | Years listed | Location(s) | Estimated population | IUCN status | Threats |
| - | - | - | - | - | - |
| Ateles hybridus Brown spider monkey Ateles hybridus | 2004 2006 2008 2010 2012 | Colombia Venezuela | unknown | Critically Endangered | habitat loss and fragmentation (agricultural encroachment, cattle-ranching, logging) hunting (bushmeat) live capture (pet trade) |
| Brown-headed spider monkey Ateles fusciceps fusciceps | 2006 2012 | Ecuador | unknown | Critically Endangered | habitat loss and fragmentation hunting (bushmeat) |
| Kaapori capuchin Cebus kaapori | 2012 | Brazil | unknown | Critically Endangered | habitat loss and degradation (selective logging) hunting (bushmeat) live capture (pet trade) |
| Rio Mayo titi Callicebus oenanthe | 2012 | Peru | unknown | Critically Endangered | habitat loss and fragmentation (rice and coffee plantations, roads, cattle-ranching) hunting (bushmeat) live capture (pet trade) |
| Alouatta guariba guariba Northern brown howler Alouatta guariba guariba | 2012 | Brazil | fewer than 250 | Critically Endangered | habitat loss (selective logging) hunting (bushmeat) disease epidemics |

## Former list members

With each new publication, species are both added and removed from the list. In some cases, removal from the list signifies improvement for the species. With the publication of the 2006–2008 list, four species were removed because of increased conservation efforts: the black lion tamarin (Leontopithecus chrysopygus), golden lion tamarin (Leontopithecus rosalia), mountain gorilla (Gorilla beringei beringei), and Perrier's sifaka (Propithecus perrieri). In 2008, the black lion tamarin went from critically endangered to endangered and the golden lion tamarin was similarly promoted in 2003 after three decades of collaborative conservation efforts by zoos and other institutions. Well-protected species such as these still have very small populations, and due to deforestation, new habitat is still needed for their long-term survival. The Hainan black crested gibbon (Nomascus hainanus), which was removed from the 2008–2010 list, still has fewer than 20 individuals left, but significant efforts to protect it are now being made. Mittermeier claimed in 2007 that all 25 species could be elevated off the list within five to ten years if conservation organizations had the necessary resources.

Unlike the changes in the 2006–2008 report, not all species were removed from the 2008–2010 list due to improvement in their situation. Instead, new species were added to bring attention to other closely related species with very small populations that are also at risk of extinction. For example, the highly endangered eastern black crested gibbon (Nomascus nasutus) replaced the Hainan black crested gibbon. The Javan slow loris (Nycticebus javanicus) replaced the Horton Plains slender loris (Loris tardigradus nycticeboides) because the former has been hit the hardest of Asian lorises, all of which are declining rapidly due primarily to capture for the exotic pet trade, as well as use in traditional medicines and forest loss. In another case, the brown-headed spider monkey (Ateles fusciceps fusciceps) was omitted from the list since no spokesperson could be found for the species. The same approach was taken with the 2012–2014 list.

Primates formerly listed in the Top 25 Most Endangered Primates: Madagascar :

| Species | Years listed | Location(s) | Estimated population | IUCN status | Threats |
| - | - | - | - | - | - |
| Prolemur simus Greater bamboo lemur Prolemur simus | 2002 2004 2006 2008 2010 | Madagascar | 500 or fewer | Critically Endangered | small, isolated populations loss of habitat and fragmentation (slash-and-burn agriculture, mining, illegal logging, cutting of bamboo) hunting (bushmeat) reduced availability of drinking water due to climatic change extreme dietary specialization and dependency on giant bamboo |
| Varecia variegata Black-and-white ruffed lemur Varecia variegata | 2010 | Madagascar | unknown | Critically Endangered | loss of habitat and fragmentation (slash-and-burn agriculture, mining, logging) hunting (bushmeat) |
| Gray-headed lemur Eulemur cinereiceps | 2004 2006 2008 | Madagascar | 7,265 ± 2,268 | Endangered | very small range (~700 $km^2)$ hybridization with red-fronted lemur (E. rufifrons) low population densities habitat loss and fragmentation (fragmented, small populations) cyclones hunting (bushmeat) |
| Propithecus tattersalli Golden-crowned sifaka Propithecus tattersalli | 2000 | Madagascar | 6,000–10,000 | Endangered | hunting (by gold miners) loss of habitat (slash-and-burn agriculture, uncontrolled grass fires, wood extraction [housing & firewood], selective logging, gold mining) |
| Hapalemur aureus Golden bamboo lemur Hapalemur aureus | 2000 | Madagascar | fewer than 5,916 | Endangered | loss of habitat (slash-and-burn agriculture, cutting of bamboo [for building houses, carrying water, making baskets and other local uses]) hunting (bushmeat) |
| Lepilemur sahamalazensis Sahamalaza sportive lemur Lepilemur sahamalazensis | 2006 | Madagascar | unknown | Data deficient | loss of habitat (agricultural encroachment, charcoal production, selective logging for local use [houses]) hunting (bushmeat) |
| Propithecus perrieri Perrier's sifaka Propithecus perrieri | 2000 2002 2004 2014 2016 | Madagascar | around 915 | Critically Endangered | loss of habitat (slash-and-burn agriculture, charcoal production, fires to clear forest for pasture, mining) hunting (bushmeat) |
| Eulemur flavifrons Blue-eyed black lemur Eulemur flavifrons | 2008 2010 2012 | Madagascar | 450–2,300 | Critically Endangered | very small range (~2,700 $km^2)$ loss of habitat (slash-and-burn agriculture, selective logging) hunting (bushmeat) live capture (pet trade) |
| Northern sportive lemur Lepilemur septentrionalis | 2008 2010 2012 | Madagascar | around 19 | Critically Endangered | very small range habitat loss (firewood, charcoal production, Eucalyptus plantations) hunting (bushmeat) |
| Propithecus candidus Silky sifaka Propithecus candidus | 2000 2002 2004 2006 2008 2010 2012 | Madagascar | fewer than 250 | Critically Endangered | very small range hunting (bushmeat) habitat loss (slash-and-burn agriculture, illegal logging, firewood) |
| Microcebus berthae Madame Berthe's mouse lemur Microcebus berthae | 2012 | Madagascar | fewer than 8,000 | Critically Endangered | loss of habitat and fragmentation (slash-and-burn agriculture, illegal logging) |
| Varecia rubra Red ruffed lemur Varecia rubra | 2012 | Madagascar | unknown | Critically Endangered | loss of habitat (slash-and-burn agriculture, illegal logging, human encroachment) hunting (bushmeat) |
| Lavasoa Mountains dwarf lemur Cheirogaleus lavasoensis | 2014 | Madagascar | ? | Endangered | |
| Gerp's mouse lemur Microcebus gerpi | 2016 | Madagascar | ? | Critically Endangered | |
| Ring-tailed lemur Lemur catta | 2016 | Madagascar | ? | Endangered | |

Primates formerly listed in the Top 25 Most Endangered Primates: Africa :

| Species | Years listed | Location(s) | Estimated population | IUCN status | Threats |
| - | - | - | - | - | - |
| Mount Rungwe galago Galagoides sp. | 2004 | Tanzania | unknown | Not evaluated | loss of habitat (logging, agricultural encroachment, charcoal production) hunting (bushmeat) |
| Sclater's guenon Sclater's guenon Cercopithecus sclateri | 2000 | Nigeria | unknown | Vulnerable | habitat loss and fragmentation (logging, agricultural encroachment, oil exploration) high human density hunting (bushmeat) |
| Mandrillus leucophaeus Drill Mandrillus leucophaeus | 2000 | Cameroon Equatorial Guinea (Bioko) Nigeria | unknown | Endangered | small range loss of habitat (clearcutting [for chipboard factories and settlement]) hunting (bushmeat, persecution as pests) |
| Tana River mangabey Cercocebus galeritus galeritus | 2002 | Kenya | 1,000–1,200 | Endangered | loss of habitat (palm oil production, logging, agricultural encroachment, grass fires intended to prevent forest regeneration, overgrazing, damming and irrigation projects) hunting (persecution as pests) |
| Cercocebus sanjei Sanje mangabey Cercocebus sanjei | 2000 2002 2004 | Tanzania | fewer than 1,300 | Endangered | loss of habitat (logging, charcoal production) hunting (persecution as pests) |
| Cercocebus atys lunulatus Sooty mangabey Cercocebus atys lunulatus | 2000 2002 2004 | Côte d'Ivoire Ghana | unknown | Endangered | habitat loss and degradation hunting (bushmeat) |
| Miss Waldron's red colobus Piliocolobus badius waldronae | 2000 2002 2006 | Côte d'Ivoire Ghana | unknown | Critically Endangered | very small populations (recent, very rapid declines in numbers) habitat loss hunting (bushmeat) |
| Gorilla beringei beringei Mountain gorilla Gorilla beringei beringei | 2000 2002 2004 | Rwanda Uganda | around 880 | Critically Endangered | two isolated populations political instability human diseases hunting (bushmeat) |
| Niger Delta red colobus Procolobus epieni | 2008 2010 | Nigeria | unknown | Critically Endangered | very small range (~1,500 $km^2)$ hunting (bushmeat) habitat loss and degradation (logging of important food trees, loss of marsh forests due to canal construction) |
| Rungwecebus kipunji Kipunji Rungwecebus kipunji | 2006 2008 | Tanzania | around 1,117 | Critically Endangered | very small range habitat loss and fragmentation hunting (bushmeat) |
| Gorilla gorilla diehli Cross River gorilla Gorilla gorilla diehli | 2000 2002 2004 2006 2008 | Cameroon Nigeria | 200–300 | Critically Endangered | small, restricted range habitat loss (agricultural encroachment, fires to clear forest or improve pasture, development activities [roads]) hunting (bushmeat, wire snares set for other wildlife) |

Primates formerly listed in the Top 25 Most Endangered Primates: Asia :

| Species | Years listed | Location(s) | Estimated population | IUCN status | Threats |
| - | - | - | - | - | - |
| Horton Plains slender loris Loris tardigradus nycticeboides | 2004 2006 | Sri Lanka | unknown | Endangered | five isolated populations habitat loss hunting (bushmeat) |
| Natuna Island surili Presbytis natunae | 2002 | Indonesia | fewer than 10,000 | Vulnerable | two isolated populations habitat loss and degradation live capture (pet trade) |
| White-headed langur Trachypithecus poliocephalus leucocephalus | 2002 | China, Vietnam | fewer than 250 | Critically Endangered | very small populations (recent, very rapid declines in numbers) habitat loss hunting |
| Miller's grizzled langur Presbytis hosei canicrus | 2004 | Indonesia (Kalimantan) | unknown | Endangered | habitat loss and fragmentation hunting |
| Black snub-nosed monkey Rhinopithecus bieti | 2002 | China | fewer than 2,000 | Endangered | habitat loss (logging, fires for agricultural use, pasture) pesticide use hunting (non-targeted [snares]) |
| Gray snub-nosed monkey Rhinopithecus brelichi | 2002 | China | around 750 | Endangered | one isolated population (vulnerable to epidemic disease or catastrophes) habitat loss (forest clearing, development for tourism, agricultural expansion, firewood) hunting (non-targeted) |
| Hylobates moloch Silvery gibbon Hylobates moloch | 2000 | Indonesia (Java) | 4,000–4,500 | Endangered | habitat loss and fragmentation live capture (pet trade) |
| Nomascus hainanus Hainan black crested gibbon Nomascus hainanus | 2000 2004 2006 | China (Hainan) | around 20 | Critically Endangered | extremely small population size suboptimal, protected habitat possible gender bias in recent births hunting (bushmeat) |
| Siau Island tarsier Tarsius tumpara | 2006 2008 2010 | Indonesia (Siau Island) | Low thousands at best | Not evaluated | island population (near an active volcano) very small range high human density hunting [bushmeat (used as snack food)] habitat degradation |
| Hoolock hoolock Western hoolock gibbon Hoolock hoolock | 2006 2008 | Bangladesh India Myanmar | fewer than 5,000 | Endangered | very small populations (recent, very rapid declines in numbers) habitat loss and fragmentation (human encroachment, tea plantations, slash-and-burn cultivation) hunting (bushmeat, traditional medicine) live capture (pet trade) |
| Pongo abelii Sumatran orangutan Pongo abelii | 2000 2002 2004 2006 2008 | Indonesia (Sumatra) | around 6,600 | Critically Endangered | recent, very rapid declines in numbers only 10 fragmented habitat units habitat loss and fragmentation (fires, agriculture and oil palm plantations, roads, logging, encroachment) hunting (pests, bushmeat) [occasional] live capture (pet trade) [occasional] |
| Pongo pygmaeus pygmaeus Northwest Bornean orangutan Pongo pygmaeus pygmaeus | 2010 | Indonesia (West Kalimantan, Borneo) Malaysia (Sarawak) | unknown | Endangered | habitat loss and fragmentation (fires, agriculture and oil palm plantations, roads, logging, encroachment) hunting (pests, bushmeat, traditional medicine) live capture (pet trade) |
| Macaca silenus Lion-tailed macaque Macaca silenus | 2010 | India | fewer than 4,000 | Endangered | habitat loss and fragmentation (agriculture and tea/coffee plantations, logging) hunting (bushmeat, traditional medicine) |

Primates formerly listed in the Top 25 Most Endangered Primates: Neotropics :

| Species | Years listed | Location(s) | Estimated population | IUCN status | Threats |
| - | - | - | - | - | - |
| Leontopithecus rosalia Golden lion tamarin Leontopithecus rosalia | 2000 | Brazil (Rio de Janeiro) | 3,200 | Endangered | habitat loss and fragmentation (fires to clear forest for pasture) live capture (pet trade) |
| Leontopithecus chrysopygus Black lion tamarin Leontopithecus chrysopygus | 2000 | Brazil (São Paulo) | around 1,000 | Endangered | small population size (11 isolated populations, but only one is viable) habitat loss and fragmentation |
| Superagui lion tamarin Superagui lion tamarin Leontopithecus caissara | 2000 2002 2004 | Brazil (Paraná and São Paulo) | fewer than 400 | Critically Endangered | small, isolated populations habitat loss and degradation (agricultural encroachment, palm heart harvesting, tourism) high human density (increased squatting by impoverished people, land speculation) hunting (bushmeat) |
| Cebus xanthosternos Golden-bellied capuchin Cebus xanthosternos | 2000 2002 2004 | Brazil (Bahia, Minas Gerais?) | unknown | Critically Endangered | habitat loss hunting (bushmeat) |
| Northern muriqui Northern muriqui Brachyteles hypoxanthus | 2000 2002 2004 | Brazil (Bahia, Espírito Santo, Minas Gerais) | fewer than 1,000 | Critically Endangered | small, isolated populations habitat loss and fragmentation hunting (bushmeat [past], sport [past]) |
| Oreonax flavicauda Yellow-tailed woolly monkey Oreonax flavicauda | 2000 2006 2008 2010 | Peru | unknown | Critically Endangered | restricted range low population densities habitat loss (agriculture, logging, roads, colonization) hunting (bushmeat, fur) live capture (pet trade) |
| Saguinus oedipusCotton-top tamarin Saguinus oedipus | 2008 | Colombia | fewer than 6,000 | Critically Endangered | habitat loss and fragmentation (large-scale agricultural production [cattle] and farming, logging, oil palm plantations, hydroelectric projects) live capture (pet trade [current], biomedical research [past]) |
| Sapajus flavius Blond capuchin Cebus flavius | 2010 | Brazil | 180 | Critically Endangered | habitat loss and fragmentation (coastal development and sugar cane plantations) live capture (pet trade) hunting (bushmeat) |

## List history

With the exception of the 2000–2002 publication, which was written collaboratively by the IUCN/SSC PSG and CI, the list has been revised every two years following the biannual Congress of the IPS. The 2002–2004 list resulted from the 19th Congress of the IPS in Beijing, China; the 2004–2006 list followed the 20th Congress of the IPS, held in Torino, Italy; the 2006–2008 list after the 21st Congress in Entebbe, Uganda; the 2008–2010 list followed the 22nd Congress held in Edinburgh, UK; the 2010-2012 list followed the 23rd Congress in Kyoto, Japan; the 2012–2014 list after the 24th Congress in Cancún, Mexico; the 2014–2016 list after the 25th Congress in Hanoi, Vietnam; the 2016–2018 list after the 26th Congress in Chicago, US; the 2018–2020 list after the 27th Congress in Nairobi, Kenya; and the 2022–2023 list after the 28th Congress in Quito, Ecuador.

The 2008 IUCN Red List of Threatened Species offered assessments of 634 primate taxa, of which 303 (47.8%) were listed as threatened (vulnerable, endangered, or critically endangered). A total of 206 primate species were ranked as either critically endangered or endangered, 54 (26%) of which have been included at least once in The World's 25 Most Endangered Primates since 2000.

Historical membership :

| | Madagascar | Africa | Asia | Neotropics |
| - | - | - | - | - |
| 2000–2002 | Propithecus candidus Propithecus perrieri Propithecus tattersalli Hapalemur aureus Hapalemur griseus alaotrensis | Gorilla gorilla diehli Gorilla b. beringei Cercocebus sanjei Cercocebus atys lunulatus Procolobus badius waldronae Cercopithecus sclateri Mandrillus leucophaeus | Trachypithecus delacouri Trachypithecus p. poliocephalus Pygathrix cinerea Rhinopithecus avunculus Pongo abelii Hylobates moloch Nomascus hainanus | Brachyteles hypoxanthus Cebus xanthosternos Leontopithecus caissara Leontopithecus rosalia Leontopithecus chrysopygus Oreonax flavicauda |
| 2002–2004 | Propithecus candidus Propithecus perrieri Prolemur simus | Gorilla gorilla diehli Gorilla b. beringei Cercocebus galeritus sanjei Cercocebus atys lunulatus Procolobus badius waldronae Procolobus rufomitratus Cercopithecus diana roloway Cercocebus g. galeritus | Trachypithecus delacouri Trachypithecus p. poliocephalus Pygathrix cinerea Rhinopithecus avunculus Pongo abelii Simias concolor Presbytis natunae Trachypithecus poliocephalus leucocephalus Rhinopithecus bieti Rhinopithecus brelichi Nomascus nasutus | Brachyteles hypoxanthus Cebus xanthosternos Leontopithecus caissara |
| 2004–2006 | Propithecus candidus Propithecus perrieri Prolemur simus Eulemur cinereiceps | Gorilla gorilla diehli Gorilla b. beringei Cercocebus galeritus sanjei Cercocebus atys lunulatus Procolobus rufomitratus Procolobus p. pennantii Galagoides sp. | Trachypithecus delacouri Trachypithecus p. poliocephalus Pygathrix cinerea Rhinopithecus avunculus Pongo abelii Simias concolor Loris tardigradus nycticeboides Presbytis hosei canicrus Trachypithecus vetulus nestor Nomascus hainanus | Brachyteles hypoxanthus Cebus xanthosternos Leontopithecus caissara Ateles hybridus brunneus |
| 2006–2008 | Propithecus candidus Lepilemur sahamalazensis Prolemur simus Eulemur cinereiceps | Gorilla gorilla diehli Procolobus rufomitratus Procolobus p. pennantii Cercopithecus diana roloway Rungwecebus kipunji Galagoides rondoensis Procolobus badius waldroni | Trachypithecus delacouri Trachypithecus p. poliocephalus Pygathrix cinerea Rhinopithecus avunculus Pongo abelii Simias concolor Trachypithecus vetulus nestor Hoolock hoolock Nomascus hainanus Loris tardigradus nycticeboides Tarsius tumpara | Ateles hybridus Oreonax flavicauda Ateles f. fusciceps |
| 2008–2010 | Propithecus candidus Lepilemur septentrionalis Prolemur simus Eulemur cinereiceps Eulemur flavifrons | Gorilla gorilla diehli Procolobus rufomitratus Cercopithecus diana roloway Rungwecebus kipunji Galagoides rondoensis Procolobus epieni | Trachypithecus delacouri Trachypithecus p. poliocephalus Pygathrix cinerea Rhinopithecus avunculus Pongo abelii Simias concolor Semnopithecus vetulus nestor Hoolock hoolock Tarsius tumpara Nycticebus javanicus Nomascus nasutus | Ateles hybridus Oreonax flavicauda Saguinus oedipus |
| 2010–2012 | Eulemur flavifrons Lepilemur septentrionalis Prolemur simus Propithecus candidus Varecia variegata | Cercopithecus diana roloway Galagoides rondoensis Piliocolobus pennantii pennantii Piliocolobus epieni Gorilla beringei graueri | Tarsius tumpara Nycticebus javanicus Macaca silenus Simias concolor Trachypithecus delacouri Trachypithecus poliocephalus Semnopithecus vetulus nestor Pygathrix cinerea Rhinopithecus avunculus Nomascus nasutus Pongo pygmaeus pygmaeus | Ateles hybridus Cebus flavius Callicebus barbarabrownae Oreonax flavicauda |
| 2012–2014 | Propithecus candidus Lepilemur septentrionalis Eulemur flavifrons Microcebus berthae Varecia rubra Indri indri | Cercopithecus roloway Galagoides rondoensis Piliocolobus pennantii pennantii Piliocolobus rufomitratus Gorilla beringei graueri | Trachypithecus delacouri Trachypithecus p. poliocephalus Pygathrix cinerea Rhinopithecus avunculus Simias concolor Semnopithecus vetulus nestor Tarsius pumilus Nycticebus javanicus Nomascus nasutus | Ateles hybridus Ateles fusciceps fusciceps Cebus kaapori Callicebus oenanthe Alouatta guariba guariba |
| 2014–2016 | Cheirogaleus lavasoensis Hapalemur alaotrensis Varecia rubra Lepilemur septentrionalis Propithecus perrieri | Galagoides rondoensis Cercopithecus roloway Piliocolobus preussi Piliocolobus rufomitratus Gorilla beringei graueri | Carlito syrichta Nycticebus javanicus Simias concolor Trachypithecus delacouri Trachypithecus poliocephalus Rhinopithecus avunculus Semnopithecus ajax Semnopithecus vetulus nestor Nomascus hainanus Pongo abelii | Ateles hybridus Ateles fusciceps fusciceps Cebus kaapori Callicebus oenanthe Alouatta guariba guariba |
| 2016–2018 | Microcebus gerpi Hapalemur alaotrensis Lemur catta Lepilemur jamesorum Propithecus perrieri Daubentonia madagascariensis | Paragalago orinus Cercopithecus roloway Colobus vellerosus Piliocolobus epieni Gorilla beringei graueri | Nycticebus javanicus Simias concolor Trachypithecus poliocephalus Rhinopithecus avunculus Trachypithecus geei Semnopithecus vetulus Macaca nigra Nomascus hainanus Pongo pygmaeus | Plecturocebus caquetensis Cebus kaapori Alouatta guariba guariba Ateles geoffroyi Ateles fusciceps |
| 2018–2020 | Microcebus manitatra Hapalemur alaotrensis Lepilemur jamesorum Indri indri Daubentonia madagascariensis | Paragalago rondoensis Cercopithecus roloway Rungwecebus kipunji Colobus vellerosus Piliocolobus epieni Piliocolobus rufomitratus Pan troglodytes verus | Nycticebus javanicus Simias concolor Trachypithecus poliocephalus Trachypithecus geei Semnopithecus vetulus Hoolock tianxing Pongo tapanuliensis | Callithrix aurita Saguinus bicolor Cebus aequatorialis Plecturocebus olallae Alouatta guariba Ateles geoffroyi |
| 2022–2023 | Microcebus berthae Lepilemur septentrionalis Eulemur flavifrons Propithecus coquereli | Paragalogo rondoensis Cercocebus chrysogaster Erythrocebus baumstarki Cercopithecus roloway Piliocolobus epieni Pan troglodytes ellioti | Nycticebus javanicus Tarsius sangirensis Semnopithecus vetulus Trachypithecus poliocephalus Presbytis femoralis Rhinopithecus brelichi Hoolock tianxing Pongo tapanuliensis | Callithrix flaviceps Cebus kaapori Cebus aequatorialis Plecturocebus grovesi Alouatta guariba Ateles fusciceps fusciceps Ateles geoffroyi |
