Diversity and distribution of microlichens in the state of Arunachal Pradesh , Eastern Himalaya , India

Abstract: The paper reports the occurrence of 404 species of microlichens belonging to 105 genera and 39 families known so far, from the state of Arunachal Pradesh, a part of the Himalaya biodiversity hotspot. Twelve species, namely Arthopyrenia saxicola, Arthothelium subbessale, Diorygma macgregorii, D. pachygraphum, Graphis nuda, G. oligospora, G. paraserpens, G. renschiana, Herpothallon japonicum, Megalospora atrorubricans, Porina tijucana and Rhabdodiscus crassus, are new distributional records for India. Astrothelium meghalayense (Makhija & Patw.) Pushpi Singh & Kr. P. Singh and Astrothelium subnitidiusculum (Makhija & Patw.) Pushpi Singh & Kr. P. Singh are proposed as new combinations and 66 species marked by an asterisk (*) are new distributional records for the state.


INTRODUCTION
The Indian state of Arunachal Pradesh, one of the most important parts of the Himalaya biodiversity hotspot (Mittermeier et al. 2005) covers an area of 83,743 km 2 (2.54 % total area of India) and is at altitudes ranging between 200 and 7,000 m above the mean sea level.Arunachal Pradesh lies between 26°28′ and 29°30′ N latitude and 091°30′ and 097°30′ E longitude.It harbours rich and unique diversity of lichen flora in northeastern India due to varied climate and topography.Various types of substrata, such as bark, twigs, leaves, soil, and rocks, provide suitable conditions for the rich growth of lichens from tropical to alpine regions.Lichenological exploration in the state was first made by Rolla Seshagiri Rao and Gopinath Panigrahi of Botanical Survey of India during 1956India during -1958.These collections were studied by Awasthi (1961) who reported 42 species of macrolichens.Subsequently, based on new collections in the state, some additional publications on foliicolous lichens, new species, and new records for India have been made (e.g., Pinokiyo et al. 2004;Dubey et al. 2007Dubey et al. , 2010;;Pinokiyo et al. 2008;Singh and Pinokiyo 2008;Singh andSwarnlatha 2011a, 2011b;Jagadeesh Ram and Sinha 2011;Upreti et al. 2011;Singh and Singh 2012a, 2012b, 2012c, 2014;Singh et al. 2013;Joshi et al. 2014).Recently, a publication on foliicolous lichens of India (Singh and Pinokiyo 2014) recorded 98 species from Arunachal Pradesh.However, the microlichens of upper northern regions of the state could not be fully explored because of rugged and inaccessible hilly terrain.In the present study, the microlichens collected so far, have been investigated, identified and enumerated together with published reports in the tabular form (Appendix, Table A1) for future users.

MATERIALS AND METHODS
Arunachal Pradesh borders the states of Assam and Nagaland to the south, and shares international borders with the countries of Myanmar in the east, Bhutan in the west, and Tibet (People's Republic of China) in the north.Several extensive collection expeditions were undertaken in different localities in the state (Figure 1).Collected specimens were deposited in the herbaria of Botanical Survey of India, Central Regional Centre, Allahabad (BSA), and Eastern Regional Centre, Shillong (ASSAM).Also studied were specimens loaned from the National Botanical Research Institute, Lucknow (LWG).Morphological observations were made using a stereomicroscope (Nikon SMZ 1500).Thin, hand-cut sections, of thalli and ascomata were mounted in water, lactophenol cotton blue (LPCB), 10% KOH and Lugol's iodine solution.All anatomical measurements were taken in water mounts and examined under a compound microscope (Nikon Eclipse 50i).Secondary metabolites were identified by thin layer chromatography (TLC) following Orange et al. (2001) and White and James (1985).All the specimens were identified with the help of authenticated specimens available in the various herbaria and published literature.Current names of the

RESULTS
This study of microlichens of Arunachal Pradesh revealed the occurrence of 404 species (Appendix, Table A1), belonging to 105 genera and 39 families (Figure 2), of which 12 species are newly recorded for the Indian lichen flora and 66 species (marked with an asterisk) are new distributional records for Arunachal Pradesh.

New combinations
Recently, phylogenetic studies on Trypetheliaceae (Nelsen et al. 2014) have shown that the species with rounded (not diamond-shaped) lumina in ascospores cluster around the Trypethelium group, while species with diamond-shaped lumina form another cluster around the Astrothelium conicum-group, regardless of their ascoma organization.Accordingly following two new combinations are proposed.subnitidiusculum Makhija & Patw., J. Hattori Bot. Lab. 73: 207. 1993

DISCUSSION
Geographically, Arunachal Pradesh is the largest state among the eight northeastern states (Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Naga land, Sikkim and Tripura) of India and harbours a wide spectrum of lichen diversity.The present study provides an idea of the diversity and distribution of microlichens in the state and provides baseline data for future research in this region.Arunachal Pradesh has characteristic lichen genera such as Coccotrema (Singh and Singh 2012c), Erythrodecton (Singh et al. 2009) and Mycoblastus (Singh and Singh 2015), which are hitherto unknown from the other parts of India.Forty-eight species (marked with an "E" in Appendix, Table A1) are endemic to India.Thus, Arunachal Pradesh has a distinct and unique lichen diversity and justifies its inclusion as a hotspot of biodiversity in the Indian Himalaya.Habitat-wise, 265 species are corticolous (67%), 98 species are foliicolous (25%), 27 species are saxicolous (7%), and four species are terricolous (1%).It is observed that the corticolous and foliicolous species are dominant and commonly distributed in almost all localities where as saxicolous and terricolous ones are scarce.
A comparison of microlichen diversity with other Indian Himalayan states indicates that the Arunachal Pradesh has the highest number of microlichen species known so far (Figure 7).The state has 404 species, but Uttarakhand has 282 species, Sikkim has 265 species, Himachal Pradesh has 155 species, Jammu and Kashmir has 149 species, and West Bengal-Darjeeling has 114 species (Singh and Sinha 2010;Upreti et al. 2010;Sinha and Jagadeesh Ram 2011;Jagadeesh Ram andSinha 2011a, 2011b;Joseph andSinha 2012, 2015;Goni et al. 2015).Similarly, a comparison among the north eastern states the Arunachal Pradesh also shows high percentage of microlichen diversity (Figure 8).
The rugged, hilly, and largely inaccessible terrain, which is cut by many rivers and streams originating from higher Himalayas, has made lichen surveys in the region extremely difficult.As a result, many areas in the north at higher elevations are still lichenologically unexplored; future exploration of these areas may provide many interesting finds.The present assessment of microlichens will be helpful in biomonitoring and climate change studies, conservation research, and sustainable utilization of lichen resources.

Check
List 11(6): 1807, 9 December 2015 doi: http://dx.doi.org/10.15560/11.6.1807ISSN 1809-127X © 2015 Check List and Authors Lists of species Singh et al. | Diversity and distribution of microlichens in Indian Himalaya species, habit and distribution in districts along with selected voucher specimen numbers are also provided.

Figure 1 .
Figure 1.Map of Arunachal Pradesh showing areas of exploration (stippled) of microlichens in various districts.

Figure 2 .
Figure 2. Total number of genera and species of per microlichen family in Arunachal Pradesh.

Figure 8 .
Figure 8. Microlichen diversity in northeastern states of India.