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Tashi Wangchuk, Bhutan Museum of Natural History c/o Nature Conservation Division, Department of Forestry Services, Ministry of Agriculture Royal Government of Bhutan, Thimphu (Bhutan) Tel. +975 232 5042, Fax +975 232 5475 E-Mail tashi_wangchuk@yahoo.com

Brief Report

Folia Primatol 2003;74:104�108 Received: December 4, 2002 DOI: 10.1159/000070007 Accepted after revision: January 11, 2003

A New Subspecies of Golden Langur (Trachypithecus geei) from Bhutan

Tashi Wangchuk David W. Inouye Matthew P. Hare

Bhutan Museum of Natural History, Nature Conservation Division, Royal Government of Bhutan, Thimphu, Bhutan

Key Words Golden langur ! New subspecies description ! Bhutan ! Phylogeny ! Biogeography

Ecological, morphological, and phylogenetic concordance support the recogni-tion of a new sub-species of golden langur (Trachypithecus geei) from Bhutan.

Extensive surveys since 1994 show that golden langurs in Bhutan occur from subtropical forests in the south to temperate and sub-alpine forests in the north [Wangchuk, 1995; Wangchuk et al., 2001]. The great variation in the species� range, from almost sea level in the south to above 3,000 m in the north, creates an abundance of ecological niches to which it can adapt in unique ways.

A distinct ecological separation between north and south is the sudden uprise created by the Main Frontal Thrust (MFT) of the Indian plate hitting into the Hima-layas [Bhargava, 1997]. Elevation south of the MFT ranges from 40 to 900 m, while north of the MFT elevation ranges from 1,000 to over 7,000 m (fig. 1). Rain-fall south of the MFT averages 5,000 mm while to the north average rainfall is 1,000 mm. Vegetation in the foothills is consequently subtropical while to the north it is temperate and alpine [Grierson and Long, 1984].

The surveys also showed that the three colobine species in Bhutan Semnopi-thecus entellus, T. geei, and Trachypithecus pileatus are allopatrically distributed, separated by rivers and mountain ranges (fig. 1). The subspecies of S. entellus north of the MFT most closely resembles the Himalayan langur S. e. achilles [Pocock, 1928], while in the foothills the subspecies resembles S. e. hector [Pocock, 1928] following the description and classification of Napier [1985]. Napier distinguishes the Nepalese races of langurs as follows: S. e. achilles as �darker browner langurs from the higher altitudes� and S. e. hector as �smaller paler grayer langurs of the lesser hills.� Sympatric capped langurs in Nagaland reveal a similar elevation- al variation, where �the yellow-bellied Presbytis p. pileata is found at 5,000 ft (1,500 m) and the red-bellied Presbytis p. durga at 2,000 ft (600 m) and be-low� [Pocock, 1939 cited in Napier, 1985].

Subspecies of Golden Langur 105 Folia Primatol 2003;74:104�108

Fig. 1. Biogeography of the langur species of Bhutan.

106 Folia Primatol 2003;74:104�108 Wangchuk/Inouye/Hare

These correspond with observed differences in body size and coat colour to the golden langurs in the north and south of Bhutan. Golden langurs in Manas and other areas in the south are smaller and of �uniform deep cream colour in dull light and bright golden in sunlight� [Gee, 1956]. Khajuria [1956], who collected the holotype, an adult female from Jumduar in Assam, describes the colour as �creamy white� with a head and body length of 488 mm and tail length of 762 mm. Figure 2 shows golden langurs photographed in Manas in south Bhutan. A paratype adult

Fig. 2. Golden langurs from Manas in south Bhutan (photo by G. Cubitt). Fig. 3. An adult male langur in Zhemgang showing the typical pelage colour of the north. Fig. 4. A troop of langurs in Zhemgang, north Bhutan.

Subspecies of Golden Langur 107 Folia Primatol 2003;74:104�108

male collected by Khajuria from the same locality has a head and body length of 720 mm and a tail length of 900 mm. In contrast, the golden langurs in the north near Trongsa and Zhemgang are larger and have darker limbs and tails.

An adult male near Dakpai in Zhemgang, accidentally hit by a passenger bus and turned in to the Forest Range Office in Zhemgang on 29 December 1999, weighed 12.2 kg and had a head and body length of 815 mm and a tail length of 1,015 mm. The dorsal regions of the forearms were dark grey to black, extending from the shoulders to the wrists. The outer shank and thigh regions were also grey to black, extending to the ankles. About 10% of the tail hair were black tipped, giving the tail a greyish appearance in the upper two thirds. The tail tip was bunched and pale. Figures 3 and 4 show langurs photographed in Zhemgang revealing this colour pattern. Both the skin and skull were deposited (accession number BNHC.1999.02) with the Bhutan Natural History Collection maintained by the Taxonomic Unit of the Nature Conservation Division, Royal Government of Bhutan. The Unit is cur-rently in the process of upgrading to the Bhutan Museum of Natural History.

This observed morphological difference is supported by phylogenetic analysis of the hypervariable control region of the mitochondrial DNA. Hair and faecal samples collected noninvasively in the field were used and amplified using nested mtDNA primers yielding 774 base pairs for 7 samples (4 golden langur, 2 capped

Fig. 5. Maximum likelihood tree from control region of mtDNA. Bootstrap values areshown in boxes and branch lengths are shown above each branch.

108 Folia Primatol 2003;74:104�108 Wangchuk/Inouye/Hare

langur, 1 grey langur). The analysis was conducted under all three optimality crite-ria to compare outcomes and search for the best tree.

High bootstrap values (90%, 1,000 replicates) from maximum likelihood analysis supports a differentiation between the golden langurs in the north and south of Bhutan (fig. 5). Figure 5 also reveals that there is support (78%, 1,000 replicates) for treating golden langurs and capped langurs as distinct monophyletic groups. The maximum likelihood score of the best tree found was ln 2529.34237. The longest branch length was that of the grey langur (0.510).

The parsimony analysis also grouped golden and capped langurs as indepen- dent monophyletic taxa. The score of the best tree found was 428. The number of changes between the outgroup (S. entellus) and the ingroup was the highest with 173 changes. Golden langurs have diverged by 52 character state changes from the common ancestor while capped langurs have undergone 49 changes. Of the total of 774 characters initially input, only 115 were parsimony informative characters while 452 constant and 207 variable characters were parsimony uninformative. The consistency index was 0.928.

Concordant fit between the biogeography, ecology, morphology and phyloge-netic tree provides consistent support for the distinction between the golden langurs in the north and south of Bhutan. Based on this support and corroborating examples from grey and capped langurs in different ecosystems and elevation zones, it is recommended that the golden langur in north Bhutan be recognised as a subspecies and be called the Bhutan langur, T. g. bhutanensis [Wangchuk, 2003], and that the subspecies in south Bhutan and Assam be maintained as T. g. geei.

Acknowledgements

Funding from the Bhutan Trust Fund for Environmental Conservation, The University of Maryland, and the Royal Government of Bhutan is gratefully acknowledged. Advice from Charles Delwiche of the University of Maryland, and Yoshi Kawamoto and Mitsuru Aimi of Kyoto University is deeply appreciated.

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