BIODIVERSITAS ISSN: 1412-033X Volume 16, Number 2, October 2015 E-ISSN: 2085-4722 Pages: 109-115 DOI: 10.13057/biodiv/d160201 Potential distribution of Monotropa uniflora as a surrogate for range of Monotropoideae (Ericaceae) in South Asia PRAKASH PRADHAN West Bengal Biodiversity Board, Department of Environment, Government of West Bengal, Salt Lake, Sector-III, FD415A, Poura Bhawan, 4 th Floor, Kolkata, West Bengal, India, 700 106. Tel.+91 8013126863,  email: shresthambj@gmail.com. Manuscript received: 12 February 2015. Revision accepted: 13 May 2015. Abstract. Pradhan P. 2015. Potential distribution of Monotropa uniflora as a surrogate for range of Monotropoideae (Ericaceae) in South Asia. Biodiversitas 16: 109-115. Monotropoideae is a mycoheterotrophic subfamily of Ericaceae. Its members are highly specific to a particular fungal family, which has attributed to the rarity and limited distribution of Monotropoideae. In the past two decades, there are considerable developments in understanding their biology and biogeography, among which, the distribution of Monotropa uniflora L. and M. hypopitys L. has been extensively studied. In this contribution, Ecological Niche Modeling of M. uniflora has been conducted to test its earlier proposed distribution in South Asia, to test the spatial scale of the said proposal, to test its potential distribution as a surrogate for range of Monotropoideae in South Asia and to prioritize conservation areas for M. uniflora in the region. The model was built with five occurrence details of the rare plant M. uniflora in Western and Eastern Himalaya, in relation to 19 bioclimatic explanatory variables, performed in MaxEnt. The results show the good performance of the model with the training AUC of 0.994. 1,50,316 square Km. of suitable areas have been predicted for the growth of M. uniflora (IHS ≥0.5) in South Asia, many areas of which is in line with earlier distributional reports. The bioclimatic variables are able to predict and suitably justify the spatial distribution of M. uniflora. The predicted range of the species could be established for potential distribution of other Asian Monotropoids like Monotropastrum and Cheilotheca. Key words: Ecological Niche Modeling, Himalaya, MaxEnt, Mycoheterotrophy, Russulaceae Abbreviations: IHS = Index of Habitat Suitability; Bio = Bioclimatic variable INTRODUCTION Mycoheterotrophy includes an obligatory reliance of achlorophyllous and non-photosynthetic plants upon specialized mycorrhizal associates for carbon influx (Klooster and Culley 2009). Monotropoideae is a mycoheterotrophic subfamily of Ericaceae, consisting of 10 genera and 15 species (Wallace 1975). Leake (1994) has reported 260 species of Mycoheterotrophic plants as endemic to Palaeotropics, extending from India in the West to Papua-New Guinea and Japan in the East. Endemic taxa of Monotropoideae have been reported from Western North America (seven species) and Asia (two Monotropastrum species and two Cheilotheca species and a variety) (Tsukaya et al. 2008), preferring to grow mostly in shady old growth forests (Min et al. 2012). Their endemism and narrow geographic range have been linked to limited distribution of their taxa specific mycorrhizal fungal partners (Kruckeberg and Rabinowitz 1985; Bidartondo and Bruns 2001), and such trophic structure has left the subfamily with very isolated and rare taxa (Klooster and Culley 2009). Monotropa uniflora L. and M. hypopitys L. though distantly related but are the only species within Monotropoideae which are distributed across Neotropics and Palaeotropics (Leake 1994). Although Leake (1994) has indicated broad range of genus Monotropa in Indian subcontinent, M. uniflora is considered regionally rare in Indian states of West Bengal (WBBB 2012; FRLHT 2015) and Meghalaya (Mir et al. 2014). Suitability of climate and presence of dense and shaded forest habitat has been attributed for the evolution of heterotrophy in paleotropics and neotropics (Leake 1994). Similarly, Ecological Niche/climate modeling has been proposed to act as a successful marker to infer the phylogeographic and demographic histories of mycoheterotrophic plants by Taylor et al. (2013). In this regard, paleo-distribution modeling of M. hypopitys in North America has been successfully conducted in MaxEnt using bioclimatic variables (Beatty and Provan 2011), however no study has been focused on Monotropoideae as a whole or any species therein in South Asia regarding their distribution in bioclimatic envelope. For planning suitable conservation action for Monotropoideae in this region, prime necessity is to prioritize areas for conservation having high suitability of the ecological niche of the taxa. In this contribution, Ecological Niche Modeling of M. uniflora has been conducted to test earlier proposed distribution of the species in South Asia, to test the spatial scale of the said proposal, to test potential distribution of the species as a surrogate for range of Monotropoideae in South Asia and to prioritize conservation areas for M. uniflora in the region.