Addition to the Odonata fauna of Tripura, India

,


INTRODUCTION
The insect order Odonata comprises of dragonflies (Anisoptera) and damselflies (Zygoptera).Members of this order are widely distributed, insectivorous, and amphibiotic.Egg and larval stages are aquatic and the adult stage is terrestrial.Odonata insects prefer hilly streams, and forested riparian habitats and most of the endemic and rare species are restricted to these habitats (Andrew et al. 2008(Andrew et al. , 2009;;Subramanian 2009Subramanian , 2012;;Mitra et al. 2010;Subramanian et al. 2011;Koparde et al. 2015).Habitats like ponds, lakes, coastal marshes, natural & man-made water bodies, water logged areas, grass lands, and paddy fields support species richness and diversity (Subramanian 2009(Subramanian , 2012;;Mitra et al. 2010;Subramanian et al. 2011;Majumder et al. 2014;Tiple & Khoparde 2015).The eastern India is one of the globally rich areas of odonates, and the forest streams and rivers of this region are natural habitats for many endemic and habitat-specialist species.In the eastern Himalaya, high endemism occurs in Khasi hills and Darjeeling-Sikkim Himalaya (Subramanian & Babu 2017).Tripura province, a small hilly State of northeastern India in Indo-Burma biodiversity hotspot zone (Myers et al. 2000), supports diverse odonate fauna (Clausnitzer et al. 2009) due to habitat diversity and micro habitat richness.

Study area
The present study was conducted at nine different locations (forested and unclassified habitats, Table : 1) of Tripura, from March 2012─May 2019 as a part of biodiversity exploration study.Geographically, Tripura lies between 22.9333°N-24.53333°N& 91.1666°E-92.35°E, and in the meeting point of two biodiversity hotspots (Eastern-Himalaya hotspot in the east and Indo-Myanmar hotspot region in the west) (Myers et al. 2000).This small north-eastern hilly state (Tripura) has a tropical savanna climate and receives an annual rainfall ranges from 1800-2400 mm approximately; south-west monsoon spread over seven months almost (April─October) and average minimum temperatures are around 20-25 0 C, maximum temperatures are around 30-35 0 C with elevation range varying from 15 m (lowest) to 930 m (highest).

Field sampling and Identification
In this opportunistic study, field observations and photography of odonates were conducted mainly on clear sunny days between 08:00 h and 12:00 h during monsoon season to record maximum species of odonates (Majumder et al. 2014).Species were recorded though random walks along potential habitats like streams, bamboo forest, small forest patch, manufactured water bodies, and deep forest habitats and followed direct search technique (Sutherland 1996) and sighting is opportunistic.Comet optical binoculars 8 x 40 NV JL 77888 were used during field observations and photographs were taken by Canon EOS 50D, Canon Power Shot SX 530 HS, Canon Power Shot SX 200 IS, and SONY DSC-HX 200V camera models and YU 5010A mobile device.At first sight, photographs were taken and individuals were identified with the help of reference books (mentioned below in identification part).If only photography was not enough for identification, then specimens were captured and these were released back to their respective habitats, after visual observation and photographic identification in field was successful.In cases where field identification was not enough Identification of recorded specimens was done with the help of identification keys provided by Fraser (1933Fraser ( , 1934Fraser ( , 1936)); Mitra (2002); Subramanian (2009Subramanian ( , 2014)); Nair (2011), and with online databases, <www.Comments: Genus Pseudocopera and species P. ciliata are reported for the first time from Tripura.Earlier, Josh & Kunte (2014) reported this species from Intanki, Peren District, Nagaland which is approximately 255 km far from Sonatala (study site-5).All distances mentioned here are aerial distance between two selective areas.

DISCUSSIONS AND CONCLUSIONS
Before this study, quality field data on distribution and habitat preference of odonates was scanty from most of the eastern Himalayan range, particularly from the southern and eastern parts including the state Tripura of India.Present study is a substantial advancement of the odonate diversity of Tripura over the earlier studies (Srivastava & Sinha 2000;Majumder et al. 2014).After this study with addition of 13 species, the updated odonate fauna of Tripura state is represented by 75 species under 49 genera (28 Anisoptera genera and 21 Zygoptera genera) and nine families (4 Anisoptera and 5 Zygoptera ); (Appendix 1).Three odonata species namely, M. montanus, D. walli and E. campioni showed Data Deficient as per IUCN Red List categories of threatened species.Among the 13 species reported here, 12 species are endemic to India except D. walli as per Subramanian & Babu (2017).P. magdalena, Macrogomphus montanus, Tetrathemis platyptera, Tramea limbata, Trithemis festiva, Z. petiolatum, Aciagrion occidentale, Argiocnemis rubescens, Mortonagrion aborense, Elattoneura campioni, Prodasineura verticalis, Pseudocopera ciliata are endemic to India recorded from this study.Members of T. festiva are found commonly near streams and those of Zyxomma petiolatum are common in shady areas surrounded by big trees and shrubs.Members of Aciagrion occidentale, Argiocnemis rubescens, Mortonagrion aborense, P. ciliata are very common in their respective study sites.However, P. magdalena, M. montanus, T. platyptera, T. limbata, Dysphaea walli, E. campioni, P. verticalis are found to be comparatively rare in their study sites.The documenting of the regional species pool from this part of India has benefited the inclusion of previously unrecorded odonate species, which will help future researchers in the understanding of species biology, distributional ranges, and prospective habitats.
, then effort was made to collect at least one individual with insect net for accurate identification in the Ecology & Biodiversity Laboratory of Tripura University under permission from the authority of Tripura Biodiversity Board, Government of Tripura [letter no.F. 22/3(6)/for JBIC/I&P/B-D/07/2336 and 4972-76 dated 07.01.2009 and 29.06.2009],respectively.Morphological characters for identification of unidentified species were studied Journal of Threatened Taxa | www.threatenedtaxa.org| 26 June 2023 | 15(6): 23327-23337 23329 J TT in laboratory using Zeiss Stemi 508 stereo zoom 8:1 microscope.Photographs of the observed habitat types explored in this study, helped in recording the habitat preference of different odonates.

Image 1 .
Google Earth image of India showing the Tripura state and different study sites of six administrative districts.
checklist of dragonflies and damselflies recorded from Tripura.It contains species from all the studies done so far from Tripura (Srivastava & Sinha 2000, Majumder et al. 2014) along with the present study (in bold fonts).

Table 1 . Geoco-ordinates of the study sites.
Khan (2018)6) location parameters such as latitude, longitude, and elevation were done with the help of Garmin eTrex Vista GPS device.Conservation status of the recorded odonates of this study was according to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species (IUCN 2020).Thirteen species of Odonata are reported as new records and added to the Odonata fauna of Tripura from this study.Of these, six dragonfly species belong to six different genera under three families, namely Aeshnidae, Gomphidae, Libellulidae, and seven damselfly species belonging to seven different genera under three families, namely Coenagrionidae, Euphaeidae, and Platycnemididae (bold marked species of Appendix 1).A detailed account of findings is given below: Earlier,Fraser (1936)reported this species from Assam andKhan (2018)reported it from different locations including Khagrachari (approximately 110 km far from Sonatala, Study site-5) from the Chittagong Division, southeastern Bangladesh.Genus Tetrathemis and species T. platyptera are reported for the first time from Tripura.Earlier, Laltanpuii (2017) reported this species from different locations including Reiek (approximately 110 Km far from Dhajanagar, Study site-3) of Mamit District, Mizoram.