Dragonflies (Odonata) from the Taquari River valley region, Rio Grande do Sul, Brazil

Abstract

A survey of Odonata was carried out in the central region of the state of Rio Grande do Sul: the Taquari River valley. This region was originally covered by deciduous and Semi-deciduous Atlantic Forest, which today only exist in a highly fragmented environment mainly due to agricultural activities. Our survey was conducted in 12 municipalities from this region, between March 2011 and April 2013. Aiming a general overview of the species composition, our sampling sites included lakes, bogs, small streams and river sections, all inside or surrounded by small forest fragments or forest areas. Fifty species of Odonata were collected comprising 29 genera and seven families. The dominant families were Libellulidae (40%) and Coenagrionidae (36%), while Aeshindae, Gomphidae and Lestidae each only comprise 6% of the total number of species. The findings revealed the presence of a highly diverse odonate assemblage, mainly represented by generalist species in human disturbed fragments and a few forest specialist species in the best preserved remnants only.

Ecoregions within the Brazilian Pampa biome reflected in Odonata species assemblies

“…We followed the method described by Renner et al . (), collecting dragonflies on sunny days during the peak period of odonate activity (between 09:00 and 16:00 h). Two persons using handheld insect nets walked along the perimeter of the site, along the water edges and marginal zones.…”

“…Part of the data set used in this study has been used in other publications by the authors (Renner et al . , ). For all analyses, the species were divided by ecoregion (below) and the sampling effort per region was checked by a rarefaction curve.…”

“…Hence, the Odonata are often used as bioindicators (Carle ; Sahlén & Ekestubbe ; Simaika & Samways ; Renner et al . ). Their life cycle involves both an aquatic larval stage and a terrestrial, aerial adult stage, for which different selection pressures apply.…”

Preliminary dragonfly (Odonata) species list from the Pampa biome in Rio Grande do Sul, Brazil, with ecological notes for 19 new records for the State

“…temporary water and flooded areas. The sampling method followed Renner et al (2015): hand-held insect nets by a team of two people, in sunny days, during the peak time of Odonata activity (between 09:00 h to 16:00 h). Each site was sampled during 30 minutes, by walking the edge and marginal zones, the distances walked were dependent on the size and type of waterbodies, varying from ca.…”

“…The Odonata fauna in Brazil is moderately known in terms of species occurrence and distribution: only 29% of the country's territory is adequately surveyed, according to De Marco & Vianna (2005), but this number is probably outdated. For the southeast and central regions several species lists are available (e.g., Costa et al 2000, Costa & Oldrini 2005, Anjos-Santos & Costa 2006, Calvão et al 2014, Bedê et al 2015, while in the southern part of Brazil these studies are more scarce, the most recently published are Kittel & Engels (2014) and Renner et al (2015Renner et al ( , 2016aRenner et al ( , 2016b, which were all conducted in the Atlantic Forest biome. Thus, we were motivated to increase the knowledge of species occurrence to the Pampa biome, the southernmost part of Brazil, where no survey of Odonata has previously been made.…”