Records of dragonflies and damselflies (Insecta: Odonata) of Dipang Lake, with two new records to Nepal

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Odonata is an order of insects that comprises dragonflies (Anisoptera) and damselflies (Zygoptera). They are carnivorous in nature. They can be taken as an excellent biological indicator of environmental conditions (Corbet 1993) and also play an important role in the ecology of wetlands (Chovanec & Waringer 2005). Many species of Odonata inhabiting agro-ecosystems play a crucial role in controlling pest populations (Tiple et al. 2008). Since they are primarily aquatic, their life history is closely linked to specific aquatic habitats (Andrew et al. 2009). Worldwide, 6,324 species of Odonata are known (World Odonata List 2020). Nepal, being rich in water resources, serves as an excellent habitat for Odonata. The earliest record of dragonflies was carried out by Selys (1854) in Nepal. Since then, there have been various other researchers who had carried out studies, including Vick (1989) who listed out 172 species with altitudinal distribution for the first time in Nepal. In recent times, Thapa (2015) enlisted 195 species from 87 genera belonging to 18 families while Conniff (2020) states that 183 different species of Odonates are recorded from Nepal till date in accordance with the modern classification.
Dipang Lake is one of the eight lakes in Pokhara Metropolitan Municipality located in Lekhnath covering a total catchment area of 2.39km 2 and total water body area of 0.14km 2 (MoFE 2018). Most of its area is covered by swampland and the lake itself, while the tributaries too serve as an excellent abode for Odonata. Khatre and Kusunde rivers are its major sources with Kahur, Kaure and Deurali rivers as other tributary streams (MoFE 2018). The lake, however, seems to have passed its glory days because of its drying water sources. Human encroachment though seems low and constant, siltation is medium and constant, pollution is medium but increasing and the number of invasive species like water hyacinth, parthenium, morning glory, Lantana camara, etc. is high and increasing (MoFE 2018). Conservation efforts though, have been undergone by NGOs like CODEFUND.
Not many studies on Odonata have been performed from this lake, however, Karen Conniff, who has been working extensively on the Odonata of Nepal, has been recording several of them in Pokhara on her blog "Nepal Odonata". This study was conducted to explore the Odonata species exclusively from Dipang Lake.
The research was carried under the biodiversity project of the Conservation Development Foundation (CODEFUND), Koteshwor, Kathmandu, Nepal. The surveys were carried out during April and May of 2019 J TT in the locality of Dipang Lake, Lekhnath, Kaski (28.180 0 N & 84.066 0 E, 670-700 m) ( Figure 1). Different areas of the lake including the swampland, inlet, outlet and the peripheries were extensively explored. The sightings were recorded capturing photos in the Sony Cyber-Shot DSC-HX90V 18.2MP camera. The GPS details of the locations and the dates were recorded on the photos themselves. The number of individuals seen was recorded in a notebook to analyze their local status. During this study, no species of Odonata were harmed. The records were photographed from a proper distance and were identified from the photographs using Karen Conniff's blog "Nepal Odonata", "Odonata of India" website and Andrew et al. (2009). Moreover, some species were identified by Karen Conniff herself.
Local status of Odonata species are categorized as; rare-only one individual recorded, uncommononly two individuals recorded, less common-only 3-5 individuals recorded, rather common-individuals recorded 6-10 in number, common-individuals recorded 11-50 in number, and quite commonindividuals recorded more than 50 in number.
A total of 28 species of Odonates including 17 species of Anisoptera (Dragonflies) and 11 species of Zygoptera (damselflies) were recorded (Table 1). Libellulidae with 16 species was the most dominant family among the Anisoptera followed by Gomphidae (one sp.). Among Zygoptera, eight species recorded belong to the family Coenagrionidae, one species to Platycnemididae, one species to Calopterygidae, and one species to Chlorocyphidae (Figure 2). Among Anisoptera, Neurothemis tullia was found to be the commonest of all while Pantala flavescens, Rhyothemis variegata, and Tramea virginia were found to be rare. Similarly, among Zygoptera, Ceriagrion coromandelianum was the most dominant species encountered. Likewise, Aciagrion approximans (Selys, 1876) also known as The Indian Violet Dartlet and Ceriagrion cerinorubellum (Brauer, 1865) also known as the Orange-tailed Marsh Dart had not been reported from Nepal before this research and is, thus, taken as species new to Nepal. This particular record for Aciagrion approximans, however, also appears  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.