A new report on mixed species association between Nilgiri Langurs Semnopithecus johnii and Tufted Grey Langurs S. priam (Primates: Cercopithecidae) in the Nilgiri Biosphere Reserve, Western Ghats, India

Abstract

Phylogenetic conservatism or rapid anthropogenic habitat modifications could increase the incidences of interspecific associations of Hanuman and Nilgiri langurs (Family: Cercopithecidae, subfamily: Colobinae) in the southern Western Ghats. Opportunistic surveys were conducted at the Silent Valley National Park, Kerala and around Devimalai Ghats, Tamil Nadu for Tufted Grey-Nilgiri Langur association. Based on the observations from Researchers, field assistants, forest staff, and local people, the data in terms of the time of the sighting, number of individuals, phenotypes of individuals, and the time the interaction lasted, were recorded. The study reports data on a troop of Nilgiri Langurs (N=13) around O Valley tea estate at Devimalai Ghat, Gudalur, Tamil Nadu with some hybrid looking individuals and a Tufted female Grey Langur amongst them. A total of six and two uni-male troops of Nilgiri Langurs and grey langurs respectively with Tufted female Grey Langurs, and aberrant coat colored infants observed at the Neelikkal section of Silent Valley National Park are also reported. The study reasonably speculates that there could be more such locations in the southern western ghats and emphasizes the need for more systematic surveys to understand and explore the ecology, behavior, molecular, and other likely factors contributing to the conservation of vulnerable Nilgiri langur (Semnopithecus johnii) populations.

Distribution, social organization, and management of Semnopithecus johnii: An umbrella species of fragmented landscape of the Western Ghats

“…(2011, 2014, 2016), Kumara and Singh (2004a, 2004b), Ramesh Kumar et al. (2018), Nag (2020), Singh, Singh, Kumara, et al. (1997), Singh, Singh, Kumar, et al.…”

“…We carried out surveys of primates in the entire Western Ghats in the last two decades. The results of these surveys were published as articles in journals including Kumar et al (2002), Kumara et al ( , 2014Kumara et al ( , 2016, Kumara andSingh (2004a, 2004b), Ramesh Kumar et al (2018), Nag (2020, , Singh et al (1998, 2016, chapters in the book or web, including Kumara and Singh (2011), Sasi and Kumara (2018), and research reports including Kumara (2007). During these surveys, all detections of Nilgiri langurs and descriptions of the distribution, group size, age-sex of the individuals, and geo-coordinates of locations of mixed-species groups of Nilgiri langurs and Hanuman langurs were extracted and compiled.…”

“…Hohmann & Sunderraj, 1990;Nag, 2020;Oates, 1982) of the mixed species groups of Nilgiri langurs and Hanuman langurs to be used as input localities for building the ecological niche modeling. We would like to add a caution here.…”

“…in India (Chetan et al., 2014). Mixed species groups are often reported from such overlapping ranges, for example, S. priam and S. johnii (Hohmann, 1988; Nag, 2020; Oates, 1982), S. priam thersites and S. vetulus philbricki (Lu et al., 2021), Trachypithecus pileatus and T. geei (Choudhury, 2008), Nasalis larvatus and T. cristatus (Lhota et al., 2022) and T. pileatus and T. phayrei (Al‐Razi et al., 2023). In some of these cases, hybridization between the mixed species was reported (Lu et al., 2021).…”

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“…These studies have enabled researchers to identify a range of directly observable and cryptic hybridization phenomena that played a role in the evolutionary diversification of this subfamily. For example, morphological (coloration), bioacoustic, and molecular evidence suggest both observable hybridization and cryptic introgression of genes between ecologically distinct langurs that co-inhabit the mosaic of evergreen and deciduous forest in the south of Indian subcontinent ( Semnopithecus johnii , S. priam, and possibly S. hypoleucos ) (Hohman, 1988 ; Ashalakshmi et al ., 2015 ; Nag, 2020 ). Hybridization between Semnopithecus priam thersites and S. vetulus in Sri Lanka is supported by behavioral evidence and observation of coat color pattern (Lu et al ., 2020 ).…”