Germain's langur

Germain's langur is part of the leaf monkey subfamily Colobinae.^[4] Two subspecies of the Germain's langur are recognized: Trachypithecus germaini germaini and Trachypithecus germaini caudalis.^[4][5][6] However, the classification of the Germain's langur has been contested, with T. germaini being grouped with other species in its subfamily.^[4][7] T. germaini and T. margarita were considered to be a single species, T. villosus, but morphological and genetic evidence has shown that they are distinct.^[4][7][8][9] T. germaini has also been grouped with T. cristatus until recent reclassifications.^[4]

Trachypithecus germaini goes by several common names such as the Indochinese lutung, Germain's langur, Germain's silver langur, Indochinese leaf monkey, and Indochinese silvered langur.^[10]

Germain's langur has black colouration on its hands and feet, as well as the upper part of its body which fades into paler grey on its underparts.^[4] They have long grey tails and white hairs on its round face.^[4] Their young have bright orange fur.^[4]

The limits of the distribution of Germain's langur are not well known, but they are currently found in Asia, specifically Cambodia, Vietnam, Lao PDR, Myanmar, and Thailand.^[2] Populations in Vietnam are severely reduced, with few sightings in the last 50 years.^[2][11] In Lao PDR, the species has no continuous range, rather multiple patches of higher relative abundance.^[2][11] Its distribution in Cambodia is widespread, but its abundance will vary from common to rare.^[2] One of the few sites with a population estimate is Keo Seima Wildlife Sanctuary where a stable population of 1487 is reported.^[12][13] In Thailand, the species is common, with many protected areas supporting large populations.^[2] Germain's langur is a terrestrial arboreal species, often found in lowlands.^[2] They prefer evergreen and semi-evergreen, riverine, mixed deciduous, and gallery forests.^[2] They are not commonly found at high elevations or hilly areas.^[2]

The diet of Germain's langur is folivorous consisting of leaves, shoots, and fruits.^[4][14] They are also observed to consume mushrooms (mycophagy) and soil (geophagy).^[14] Their folivorous diet dictates a resting period, in which they can undergo the process of rumination.^[14][15]   

Trachypithecus germaini, and other Asian colobines, are generally less frequently engaged in social interaction than frugivorous primates such as macaques.^[14][16] They have a lower affinity to social behaviour in comparison to feeding and resting which makes up the majority of their day.^[14] However, T. germaini is often found in troops of 10 to 50 individuals in close social proximity.^[4][14]

Predators of Trachypithecus, including the Germain's langur, include leopards, tigers, dholes, and large snakes.^[17] A variety of small carnivores will feed on the young.^[17]

Prevalent threats to Germain's langur include hunting, exotic pet trading, and habitat loss due to agricultural expansion.^[2]

T. germaini is considered endangered by the IUCN, with a greater than 50% decline in the past three generations.^[2] It is listed under CITES Appendix II, meaning that trade of the species must be controlled to avoid endangerment.^[2][18]

Little conservation efforts have been made, despite the species designation.^[7][14] Several protected areas have been established across its range which aids in the conservation of the species. The species has been recorded in numerous protected areas in Vietnam and Thailand.^[2] In Vietnam, their populations have increased in two protected areas, Phú Quốc National Park and Kiên Lương Karst Area, demonstrating the importance of conservation efforts.^[19]