The identification of Takin Budorcas taxicolor (Mammalia: Bovidae) through dorsal guard hair

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Takin
Budorcas taxicolor Hodgson (1850) is a heavily built and clumsy-looking animal, native to northeastern India, Bhutan, China, and northern Myanmar (Salter 1997). Budorcas taxicolor is usually identified by its external morphology, i.e., long, shaggy coat that varies from golden yellow to deep dark brown, a dark stripe running on the dorsal side from head to tail, and a dark brown face (Menon 2014). In the present study, however, it was found that B. taxicolor can also be identified with the help of its hair samples. Mammalian hairs have certain advantages from the viewpoint of taxonomy and systematics (Sarkar et al. 2011). There are many works worldwide on hair identification of different species of mammals (Mayer 1952;Brunner & Coman 1974;Moore et al. 1974;Teerink 1991). In India, studies on the hair of mammals were carried out on Artiodactyla (Koppikar & Sabins 1976), Rodentia (Sarkar 2012), Carnivora (Chakraborty & De 2010), and Primates (Sarkar et al. 2011). This study attempts to find out the hair characteristics of B. taxicolor, which was hitherto unknown.
A total of five tufts of dorsal guard hair was collected from the five preserved skins of B. taxicolor housed at the National Zoological Collections of the Zoological Survey of India, Kolkata, India, and was processed by following the method of Teerink (1991). Subsequently, the morphological characteristics of hair such as total length, diameter, and profile (n=20) were recorded using a dial calliper and hand lens. The cuticular scale characteristics were studied according to the standard methodology (Brunner & Coman 1974;Teerink 1991) and the scale pattern, margin, margin distance, and count of the hair were studied by moulding the hair in clear varnish overnight and observing the impressions of its cuticular scales. The medullary characteristics such as composition, structure, and margins were recorded from the hair cleaned and mounted in a solution of xylene and DPX (50:50), after Chakraborty et al. (1996). The transverse section of hair too was performed as per Chakraborty et al. (1996). Different terminologies were followed according to Brunner & Coman (1974) and Teerink (1991). The photomicrographs were taken using a camera fitted with an optical light microscope (Olympus BX41) and scanning electron microscope (ZEISS Evo18 -special edition).
The hair of B. taxicolor can be easily identified by its morphologic and microscopic characteristics ( Table 1). The dorsal guard hair of B. taxicolor studied is bicoloured, with alternated bands of earth yellow and coffee colours. The profile of the hair is undulated. The total length of hair varied greatly from 13.6mm to 51.6mm (30.4±12.8mm); similarly, the diameter of hair varied from 84.9µm to 258.8µm (215.6±25.2µm). The cuticular characteristics were recorded as follows: scale positiontransversal, scale patterns -irregular wave, the structure of scale margins -rippled, and the distance between scale margins -near (Images 1a,b). All the measurement values of cuticular scales varied greatly and the average values were recorded as follows: cuticular scale count (per mm length of hair): 146.4±15.8µm, length of cuticular scale 98.8±12.1µm, and width of cuticular scale 11.1±1.1µm. The medullary characteristics were recorded as follows: the composition of medulla -unicellular irregular, the structure of medulla -uniserial ladder, and form of the medulla margins -scalloped (Image 1c); the average width of the medulla was recorded as 65.6±3.9µm. The shape of the transverse section was observed as circular (Image 1d).
A study by Kamalakannan (2015) on a total of 17 species of artiodactyls (11 bovids, four cervids, one suid, and one mouse deer) was found that the microscopic characteristics of hair of all the species were nearly the same, except in B. taxicolor. The dorsal guard hair of B. taxicolor possesses completely unique microscopic characteristics, especially that of the medulla (Image 1c) that differs from other species of mammals. According to the study, the unique structure of the medulla, uniserial ladder, was found only in B. taxicolor and was not reported earlier. The irregular wave of scale patterns, the rippled scale margins of the cuticle, and the circular shape of a transverse section of hair also determined the species identity of B. taxicolor, as these characteristics are infrequent in other species of mammals.
Methods of hair identification need exact identification keys (Brunner & Coman 1974;Teerink  www.threatenedtaxa.org The Journal of Threatened Taxa is dedicated to building evidence for conservation globally by publishing peer-reviewed articles online every month at a reasonably rapid rate at www.threatenedtaxa.org. All articles published in JoTT are registered under Creative Commons Attribution 4.0 International License unless otherwise mentioned. JoTT allows unrestricted use of articles in any medium, reproduction, and distribution by providing adequate credit to the authors and the source of publication.