Diversity and distribution of odonates in Rani Reserve Forest, Assam, India

Abstract

Odonata are the bioindicators of freshwater ecosystem health and is recognised as an excellent ‘flagship’ group among insects. Baseline knowledge on the diversity and distribution of odonates over spatiotemporal scale is the key to biodiversity conservation. Rani Reserve Forest of Assam is a mosaic of all the habitat types suitable for odonates. The present work aims at studying the diversity and distribution of Odonates in Rani Reserve Forest. The study was carried out from December 2014 to November 2017 by categorising the study area into three major habitat types: 1. lentic system, 2. lotic system and 3. terrestrial woodland. A total of 67 species belonging to 44 genera, representing 11 families were recorded. First published records of three species, Onychothemis testacea (Libellulidae), Philoganga montana (Philogangidae) and Indocnemis orang (Platycnemididae) from the state are also provided herewith. Species richness was the highest in lentic system whereas recorded the lowest in running waters of larger forested streams. Shannon diversity index also indicated that the lentic system is relatively diverse (2.95) and smaller streams of the lotic system showed the highest species evenness (0.87). Libellulidae (43%) was found to be the most dominant family belonging to suborder Anisoptera followed by Coenagrionidae (22%) of suborder Zygoptera. Philogangidae (1%) recorded the lowest number of species. Taxonomically related species showed distinct ecological segregation within these different habitat types occupying different microhabitats therein.

A Checklist of Odonata (Insecta) of Dibrugarh District of Assam, India

“…An unidentified species of Burmagomphus genus was recorded from Mohanaghat area of Dibrugarh city during the study. A similar type of unidentified species belonging to Burmagomphus genus was also reported from Rani Reserve Forest of Assam (Thakuria and Kalita, 2021) [38] . Jaganathan was also mentioned an unidentified Burmagomphus member in his checklist 'Odonates of Jeypore'.…”

“…Laidlaw (1914) [28] described Argiocnemis aborense (synonym Mortonagrion aborense) on the basis of a single male from Dibrugarh, North Eastern Assam, in his monograph on Indian Odonata. Jaganathan was complied a checklist of about 40 dragonflies and damselflies species in Jeypore rain forest of Dibrugarh district (www.jeyporerainforest.com) [38] . Sourabh Biswas, Somen Sarkar and Vidya Venkatesh photo documented nine species of odonates from the Jeypore reserve forest (www.indianodonata.org) [39] .…”