Vietnam Primate Conservation Status Review 2002 - Hoang Lien ...

3.1 Francois’ langur
Trachypithecus francoisi (Pousargues, 1898)
3.1.1 Taxonomy
3.1 FRANCOIS’ LANGUR - Trachypithecus francoisi
Trachypithecus francoisi was first described by Pousargues (1898) from a specimen collected in southern
Guangxi Province, China (22°24’N / 106°59’E). Six other taxa, each with a different pattern of white,
grey or yellowish on a generally black or dark brown coat, have in the past usually been referred to as
subspecies and formed the francoisi group. They include the Cat Ba langur, Delacour’s langur, Whiteheaded
langur, Hatinh langur, Lao langur and Black langur.
Brandon-Jones (1984) argued that some of these taxa were distinctive at the species level.
Studies in the field and in captivity (Nadler, 1994, 1995c, 1997b), genetic research (see 2.3, Roos,
2000; Roos et al., 2001) and parasitological findings (Mey, 1994) strongly suggest that some taxa, in
the past usually defined as francoisi are distinct species. Groves (2001) listed all taxa as distinct
species. Hence, this section refers to francoisi as a monotypic taxon.
3.1.2 Description
The pelage is glossy-blackish and only a narrow tract of slightly elongated white hair runs from the
corner of mouth along the side of the face to the upper edge of ear pinna. There is a tall pointed crest
on the crown of the head. The hair of the lateral parts of the body is long. Females have a depigmented
pubic patch clothed with white to yellowish hairs.
Information about an all-black form without white cheeks is known from several areas where francoisi
occur (Ratajszczak, 1990; Ratajszczak cit. in Brandon-Jones, 1995; B. Martin, pers. comm.; T. Nadler,
pers. comm.). It is very unlikely that a second taxon exists widespread sympatrically with francoisi.
Probably there are occasionally melanistic individuals like the melanistic morph “ebenus” in T. laotum
hatinhensis. Observations in an area allegedly with the all-black form (s. locality Binh An Village,
Chiem Hoa District, Tuyen Quang Province) and the fact that no specimen of the all-black form exists
support the assumption that the all-black form is merely an incomplete observation. Langur sightings
are mostly made close to the sleeping sites at dusk or dawn, and recognizing the white cheeks is often
hardly possible.
External measurements (adult)
n mm average Source
Head/Body length
male 4 510-635 565 Brandon-Jones, 1995
female 3 590-670 623 Brandon-Jones, 1995
Tail length
male 4 805-900 863 Brandon-Jones, 1995
female 3 830-900 877 Brandon-Jones, 1995
Weight kg
male 11 6,4-7,85 7,05 Mei Qu Nian, 1998
female 1 7,2 Brandon-Jones, 1995
8 5,5-7,9 6,69 Mei Qu Nian, 1998
? 2 6,5/7,2 Dao Van Tien, 1985
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