Diversity and endemism of butterflies of montane forests of Eravikulam National Park in the Western Ghats , India

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The Western Ghats is one of the biodiversity hot spots of the world (Myers et al. 2000).This region is rich in endemism including butterflies and has been of great interest for biogeography.The natural habitats in the Western Ghats is under tremendous pressure from the biotic influences (Jha et al. 2000;Mittermeier et al. 1998).Butterflies are suitable for biodiversity studies, because their taxonomy and geographic distribution are better understood compared to many other taxonomic groups (Pandhye et al. 2012).Butterflies are also regarded as good indicators of habitat quality as many species exhibit habitat preferences and seasonality (Larsen 1988;Kunte 1997).Butterflies are sensitive biota, which get severely affected by environmental variations and changes in forest structure (Pollard 1991).India has around 1,501 species of butterflies, out of which 336 species have been reported from the Western Ghats (Kunte et al. 2018).Of the 336 species of butterflies of the Western Ghats, 316 species have been reported from Kerala (Palot et al. 2012).
Although quite a few studies have been done on the butterflies of the Western Ghats (Gaonkar 1996;Kunte 2000Kunte , 2008;;Kehimkar 2008;Padhye et al. 2012), very little is known about the butterflies of the montane habitats of the southern Western Ghats.Some of the earlier documentation on butterfly fauna from the Western Ghats include-100 species from Silent Valley National Park (Mathew & Rahamathulla 1993), 124 species from Parambikulam Wildlife Sanctuary (Sudheendrakumar et al. 2000), 75 species from Siruvani Reserve Forests (Arun 2003), 73 species from Shendurney Wildlife Sanctuary (Mathew et al. 2004), 74 species from Peechi-Vazhani Wildlife Sanctuary (Mathew et al. 2005), 24 species from Kalakkad-Mundanthurai Tiger Reserve (Ambrose & Raj 2005), 75 species from Anaikatty Reserve Forests (Eswaran & Pramod 2005), 53 species from Neyyar Wildlife Sanctuary (Mathew et al. 2007), and 282 species from the Kerala part of Nilgiri Biosphere Reserve (Mathew 2016).A checklist of butterflies of Western Ghats reported 834 species of plants as larval host plants of 320 butterflies (Nitin et al. 2018).In this paper we give an account of the butterfly fauna of the montane forests of Eravikulam National Park, based on a fourmonth long study done in 2014.

Study Area
Eravikulam National Park (ENP) (Fig. 1) is located between 10.08333-10.33333 0N & 77.00-77.16 0E in Idukki District of Kerala.The ENP forms part of the Munnar Hills, a part of the High Ranges of Western Ghats, which has six protected areas, viz., Anamudi Shola National Park, Pampadum Shola National Park, Mathikettan Shola National Park, Chinnar Wildlife Sanctuary, Kurinjimala Wildlife Sanctuary, and ENP; it is contiguous with the Palni Hills and Anamalai Hills.The ENP has an extent of 97km 2 and the terrain is undulating with grassland and shola, the stunted high altitude evergreen forests, as the dominant vegetation.
Climate: Eravikulam has a tropical montane climate.
The average annual rainfall is about 5,000-6,500 mm.The area receives both south-west as well as north-east monsoons.The mean monthly minimum temperature is 11.9 0 C, while the mean monthly maximum temperature is 22.5 0 C. The altitude of ENP ranges from 1,800-2,695 m, typical of a montane landscape and the highest peak is Anamudi (2,695m).Vegetation: The major plant communities found within ENP are grasslands, shrub lands, and forests.The terrain above 2,000m is covered primarily by grasslands (~60%), about 25% by shola forests, 8% by southern subtropfical hill forest, and 7% by shrubs (Menon 2001).

Methods
The study was conducted from September 2014 to December 2014.The whole of the study area was divided into nine blocks based on topography and drainage (Table 1) and five days each were spent on each of these blocks.At each basecamp two to three hour long transects were walked in the morning from 10:00-13:00 hr.No afternoon transects could be done because of the unfavourable weather conditions, such as mist, cloud and northeastern monsoon rains.During these transect walks, the butterflies were identified to the species level and the number of individuals were counted.Attempt was also made to photo-document every species of butterflies sighted.The butterflies were identified using the field guides of Kunte (2000) and Kehimkar (2008), and for taxonomy and nomenclature, we followed Kunte et al. (2018).

Results
A total of 85 species of butterflies belonging to six families such as, Papilionidae (10 species), Pieridae (15), Nymphalidae (36), Riodinidae (1), Lycaenidae (9), and Hesperiidae (14) (Table 2) were identified from the montane habitat of ENP.This included eight species that are endemic to the Western Ghats.They are Sahyadri Birdwing Troides minos, Nilgiri Clouded Yellow Colias nilagiriensis, Red-disc Bushbrown Heteropsis oculus, Nilgiri Four-ring Ypthima chenui, Palni Four-ring Ypthima ypthimoides, Palni Fritillary Argynnis castetsi, Nilgiri Tiger Parantica nilgiriensis and Striped Hedge Hopper Baracus subditus.The proportion between the endemic and non-endemic species of butterflies in the different basecamps are given in Fig 2 .The basecamps such as Meenthotty, Rajamala, Anamudi and Eravikulam-Kolukkan recorded the greatest proportion of the endemic butterflies at ENP, while the Lakkam Kudi basecamp recorded the greatest proportion of the nonendemic species of butterflies.While the basecamps that recorded the greatest proportion of endemic butterflies were all within the core zone of the ENP, the Lakkam Kudi basecamp is very close to human habitation and the elevation is also the lowest.The Palni Four-ring found to be the most abundant species among endemic species was found in ENP.
The only threatened species of butterfly recorded as per the IUCN category was the Nilgiri Tiger Parantica nilgiriensis.It belonged to the Near Threatened category (Lepidoptera Specialist Group 1996).The relative abundance study revealed that 27.05% of species of butterflies belonged to very rare (VR) followed by  28.24% of species that were rare (R) (Table 2).This is the first ever documentation of the butterflies of a montane habitat in the Western Ghats, which highlights the significance of these habitats on the conservation of high altitude, endemic butterflies of the Western Ghats.

Figure
Figure 1.Location map of Eravikulam National Park

Figure
Figure 2. Percentage relative abundance of endemic and non-endemic species of butterflies in different study locations of Eravikulam National Park