An insight into the butterfly (Lepidoptera) diversity of an urban landscape: Guwahati, Assam, India

The paper deals with the butterfly diversity of Guwahati, Assam, India which was the result of a survey conducted from April 2016 to July 2020. During the study period we recorded 249 species of butterflies belonging to six families namely Papilionidae (24 species), Pieridae (23 species), Lycaenidae (57 species), Riodinidae (two species), Nymphalidae (97 species), and Hesperiidae (46 species). Twenty-eight species were recorded from commercial areas, 74 species from residential areas, and 248 species from forested areas. Nineteen species were found to be very common, 39 species common, 50 species fairly common, 53 species uncommon, 57 species rare, and 31 species very rare. Twenty-four species and nine subspecies including Discophora sondiaca, Athyma selenophora, and Athyma kanwa phorkys are legally protected under different schedules as per the Indian Wildlife Protection Act (1972).


INTRODUCTION
Guwahati (26. 1859°N & 91.7477°E) is the capital city of the state of Assam having a population of around 9.6 lacs with a population density of 4,370 per sq.km with a total area of 216.79km 2 . Guwahati is the largest metropolis of northeastern India and is also the business capital of the region. The city is ecologically very important as it enjoys being a part of the Indo-Burma global biodiversity hotspot. It has a tropical monsoon climate and receives approximately 1,600mm of rainfall annually, with an average annual temperature of 23°C. Due to rapid urbanisation, there is a continuous loss of forest cover with a loss of 160.34ha/year between 2010 and 2015 (Yadav & Barua 2016) (Figure 1). Most of the forest patches are of moist deciduous type (Purkayastha 2012(Purkayastha , 2015. The pattern of habitat mostly present in and around the city includes forest patches, scrublands, grasslands, secondary plantations, wetlands, agricultural lands, and human habitations. The city is surrounded by eighteen hill ranges including eight reserve forests (South Kalapahar RF, Fatasil RF, Jalukbari RF, Gotanagar RF, Hengrabari RF, Sarnai Hill RF, Garbhanga RF, Rani RF) and two wildlife sanctuaries (Deeporbeel WS and Amchang WS). The Deeporbeel WS is also an internationally acclaimed wetland and has been declared as a RAMSAR site in 2002. The mighty Brahmaputra River flows through the heart of the city for about 25km eventually dividing it into northern and southern areas (Devi & Bhattacharyya 2015). Apart from butterflies, 26 species of amphibians, 57 species of reptiles, 214 species of birds, and 36 species of mammals have been recorded from the city (Purkayastha 2018).
Some of the recent work on butterflies of Assam were based on protected areas (Karthikeyan & Venkatesh 2011;Gogoi 2013aGogoi ,b, 2015Neog 2015;Singh 2015Singh , 2017Singh et al. 2015). In this paper we want to extend the available knowledge on the butterflies of the region by presenting, for the first time, a publication on the checklist of butterfly diversity of the urban landscape of Guwahati city of Assam, India.

MATERIALS AND METHODS
Extensive field surveys were carried out throughout all the seasons from April 2016 to July 2019 in different landscapes in and around Guwahati (Figure 1). The field study was conducted mostly during early mornings from 06.30h till 12.00h and occasionally during late afternoons till dusk from 16.30h till 17.30h. Thus, a total of five man hours was invested per survey during the study period which also includes investigating the residential localities. Pollard walk methodology (Pollard 1982) was done to spot the butterflies by walking on the trails as much as possible (3-10 trails) in the forested regions, the focus was mostly confined to the tracks/trails surrounded by flowering plants, bushes, plantations and trees present in and around the loose soils, mud, rocks and stones very close to streams such that the butterflies could be observed feeding on nectar, basking and mud-puddling respectively. The specimens were observed, photographed and identified using field literature (Evans 1932;Wynter-Blyth 1957;Kehimkar 2008;Kunte et al. 2020). Depending upon the abundance of the individuals spotted throughout the survey, the species were categorised as Very Common: 25 or more individuals recorded, Common: 15-25 individuals recorded, Fairly Common: 11-15 individuals recorded, Uncommon: 6-10 individuals recorded, Rare: 3-5 individuals recorded, Very Rare: less than three individuals recorded (

RESULTS AND DISCUSSION
During the survey period, a total of 249 species of butterflies were recorded from in and around the city belonging to six different families namely Papilionidae, Pieridae, Lycaenidae, Nymphalidae, Riodinidae, and Hesperiidae (Table 1, Image 1-100).

Account of each family from the study site
Papilionidae: A total of 24 species in this family were recorded. Among these, only one species namely the Papilio castor has legal protection and had been listed as Schedule I of the Indian Wildlife Protection Act, 1972 (IWPA) and the rest were non-scheduled species. Papilio polytes was found to be 'Very Common' as it was the most encountered species in a variety of habitats (commercial residential and forested areas. Lamproptera curius and Graphium agetes were found to be 'Very rare' as they were spotted only twice in and around the forested regions (Amchang WS and Rani Reserve Forest) throughout the field study.
Pieridae: A total of 23 species in this family were documented during the survey and the subspecies Appias albina darada (Table 1) is legally protected as Schedule I under IWPA. Most of the species of this family were observed in and around forests and residential localities ( Most of the species of this family were recorded from in and around the forest patches. During the study period, a mating pair of the Pea blue Lampides boeticus was observed late in the afternoon during April 2018 at Nilachal Hills. Riodinidae: Only two members of this family have been recorded in the study area, namely Zemeros flegyas which was the most encountered species of this family, Abisara echerius was recorded only once during the survey from the Garbhanga-Rani reserve forest. (Table 1).
Nymphalidae: Nymphalidae comprises the most diverse group of butterflies representing 97 species recorded in and around the city, some of which are legally protected under IWPA, 1972 which includes one species listed in Schedule I, 11 species listed in Schedule II, two species listed in Schedule IV ( Table 1), subspecies Euripus nyctelius nycteliu, Euploea midamus rogenhoferi, and Athyma kanwa phorkys (Table 1) are listed in Schedule II of the IWPA while the others are non-scheduled. Some of the members of this family

Threats
The major threats perceived to the butterfly population in the study are · Habitat alteration: Due to development activities the prime habitat and host plants of butterflies are fast vanishing and are replaced by human settlements. Due to scarcity in living space within Guwahati, small kitchen gardens are being lost at a rapid pace which once harboured a sustainable population of butterflies. Again in urban landscape most of the roads are tarred or made of concrete making it hard for butterflies to seek nutrients from the mud (mud-puddling).
· Agriculture: As the city expands, it is eating into its peripheral agricultural land, which in-turn is eating into adjacent forested areas, a prime habitat for butterflies. To suffice need of ever rising population, the agricultural land are using fertilizers and pesticide more than ever before, creating a negative impact on butterfly population.
· Invasive species: Invasive species of both plant and animal are impacting butterfly population in a negative way. Plants like Mimosa pudica are competing with native plant species whereas introduced lizard species Hemidactylus flaviviridis are eating into butterfly and other insect population. Feral species of cats also hunt butterflies.
· Climate change: Urban areas are the prime generators of climate change and thus the effect of climate change are felt more in urban landscape. The ever increasing heat gradient along with urban heat island effect is presenting challenges to wide range of biodiversity including butterflies.
· Lack of public awareness: Most urban dwellers are totally unaware of the importance of butterflies in their ecosystem. An average urban dweller's mindset has been calibrated as such that only larger mammals conservation concerns holds importance to him if at all.  www.threatenedtaxa.org The Journal of Threatened Taxa (JoTT) 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 allows unrestricted use, reproduction, and distribution of articles in any medium by providing adequate credit to the author(s) and the source of publication.

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