Immature Odonata-Anisoptera in the Iguatemi river basin , upper Paraná River , Mato Grosso do Sul State , Brazil

This study present an inventory of the genera of Odonata-Anisoptera in lotic environments of the Iguatemi River basin, upper Paraná River, Mato Grosso do Sul State, Brazil. Samplings were performed from December 2006 to February 2009 in the Iguatemi River and eight streams of the basin. We collected 739 immature Odonata, distributed in 25 genera and three families; of which one genus represent a new record for the Mato Grosso do Sul State. Progomphus, Tramea, Elasmotemis, Macrothemis, Aphyla and Phylocycla were the most representative genera in the Iguatemi River basin. The genus accumulation curve predicts an increase of new genera for the Iguatemi River basin.


Introduction
Insects are an important component of invertebrate assemblages in almost all water bodies, and often numerically dominant (Rincon & Cressa, 2000, Graça et al., 2004).The distribution of this group in aquatic environments is mainly influenced by physical-chemical and biogeographical factors and by the habitat structure (Baptista et al., 2014).
Among the insects, the order Odonata, popularly known as dragonflies, is a group with low number of species, compared with other groups of insects (Buzzi, 2013), characterized by present aquatic nymphs and terrestrial flying adults (Corbet, 1980).Adults of this order are among the best known insects with respect to taxonomy and distribution (Kalkman et al., 2008).They have beautiful colors and acrobatic skills that fascinate the man for centuries.They are diurnal insects, found near water bodies, but some species circulate widely even in areas far from their breeding niche (Clausnitzer et al., 2009).In turn, immatures are widely distributed in the aquatic environment; have graybrown coloring and primarily benthic mode of life (Corbet, 1980, Remsburg & Turner, 2009).These organisms are important biological components structuring freshwater ecosystems, with a key role in the food chain because they are predators at all stages of their life cycle (Corbet, 1999, Carchini, Della-Bella, Solimini, & Bazzanti, 2007) and are food sources for fish, amphibians and reptiles (Souza & Costa, 2006).Besides, they are used as indicators of human disturbance affecting the aquatic environment (Simaika & Samways, 2011, Monteiro-Júnior, Couceiro, Hamada, & Juen, 2013, Dutra & De Marco, 2015).
Considering that knowledge of the basic characteristics of biological assemblages is the first step for the development of effective conservation policies (Súarez et al., 2011), this study present an inventory of the genera of immature Odonate-Anisoptera found in lotic environment of the Iguatemi River basin, upper Paraná River, Mato Grosso do Sul State, Brazil.Thus, this survey should serve as a reference for the region, partially supplying a biogeographic gap in the knowledge of the Odonata fauna of this basin.

Study area
The Iguatemi River basin, upper Paraná River, is located at the Southern end of the Mato Grosso do Sul State (MS), Brazil, occupies 9.595,82 km 2 area and contains a large network of small streams.The Iguatemi River is a floodplain river with meandering course witch flows from an average altitude of 520 m on its headwater (municipality of Coronel Sapucaia/MS), runs, approximately, 235 km until get to 226 m altitude on its mouth atthe right bank of the Paraná River (between the municipalities of Mundo Novo/MS and Guaíra/PR).
The vegetation remaining in the study area corresponds to the Atlantic Forest biome (semideciduous forest).The climate of the region is tropical of altitude with two distinct periods related to rainfall dynamics: a rainy period (October to March) and a dry period (April to September) with annual mean temperature between 21 and 28ºC and rainfall between 1,000 and 1,500 mm (Godoy, 1986, Campo, 2001).
The area covered in this study (23°13' 27.35" S -55° 25' 14.43" W and 23° 55' 24.66" -54° 9' 24.10" W) included the Iguatemi River and eight streams (Comprida, Nhu-Verá, Cerro-Verde, Guaçú, Douradão, Água Boa, Perobão and Santa Maria) of the Iguatemi River basin.Among the environmental impacts in this basin, siltation is the most prominent, resulting from susceptibility of the sandy soil to erosion and lack of soil conservation practices in the drainage basin.Another important factor in this scenery is the current conservation of the riparian vegetation, ranging from the presence of forest fragment remnants in stretches of the Iguatemi River margin and in some of its tributaries to the complete replacement with pastures and crop cultivars.

Sampling
Thirty-one sampling sites were established in the Iguatemi River basin, as follows: i) thirteen sites were located in the Iguatemi River channel; ii) three in each of the streams Guaçú, Douradão, Água Boa, Perobão and Santa Maria, comprising the upper, intermediate and lower stretches thereof, totaling 15 sites and; iii) one site in each of the streams Comprida, Nhu-Verá and Cerro-Verde (Figure 1).
Sampling were conducted fortnightly from December 2006 to October 2007 in the Douradão and Guaçú Streams and the Iguatemi River (lower stretch); quarterly from January to November 2008 in the Perobão, Água Boa and Santa Maria Streams and the Iguatemi River (lower section); and only the months the January and February 2009 in the Cerro Verde, Nhu-Verá and Comprida Streams and the Iguatemi River (upper and middle stretch).
For a better representativeness of the Odonata fauna, samples were taken from the water surface, aquatic vegetation and sediment.Samples of the water surface were obtained with a conicalcylindrical net (0.5 mm mesh size).The individuals associated with the aquatic vegetation were collected using a sieve (3.0 mm mesh size).The individuals in the sediment were caught with the use of two samplers, a D-net (3.0 mm mesh size) for the capture of epifauna, and Petersen type grab sampler for the capture of infauna.For sampling optimization, we also included Odonata (from different substrates in the streams) caught along with fish samplings (not used in this study) by electrofishing (two dip nets and a portable generator -Toyama 1600, 220V, DC).The length of each stretch sampled by this methodology was established according to Fitzpatrick et al. (1998)  A single pass of dip nets was used to take immature Odonata in each site.At the end of each stretch it was installed blocking nets (10.0 x 2.0 m; 5.0 mm mesh size) to capture the material carried by the flow.The use of these sampling methods is justified on the basis of differences in equipment efficiency on different substrates (Alves & Strixino, 2003, Juen, Cabette, & De Marco, 2007).
In the laboratory, samples were washed through a set of sieves with different mesh sizes (2.0, 1.0 and 0.5 mm).Samples from the water surface, marginal vegetation, sediment and electrofishing were sorted using a transilluminated tray, stored in labeled vials and preserved in 70% alcohol.Immature individuals of Odonata were identified to the lowest possible taxonomic level, based on Carvalho and Calil (2000), Costa, Souza, and Odrini (2004), Lencione (2005) and Souza, Costa, and Oldrini (2007).Voucher genus are deposited in the Laboratório de Ecologia Aquática of the Universidade Estadual de Mato Grosso do Sul, Unidade Universitária de Mundo Novo, MS, Brazil.
The assemblages attributes assessed in this study were composition and richness.The efficiency of the sampling effort was evaluated by the collector's curve and the estimated number of genera was calculated using the first order Jackknife estimator.Both analyses were performed for the Iguatemi River basin using the software PCord 5.0 (McCune & Mefford, 2006).

Results and discussion
The 739 immature Odonata collected were distributed in 25 genera and three families, being that genus Desmogomphus is a new record for the Mato Grosso do Sul State.The family with the greatest number of genera was Libellulidae with 13 genera, followed by Gomphidae (09 genera) and Aeshnidae (03 genera) (Table 1).Progomphus (148 individuals), Tramea (80 individuals), Elasmotemis (65 individuals), Macrothemis (58 individuals), Aphylaand Phylocycla (56 individuals each), were the most abundant genera, contributing with 62.7% of the collected individuals.
Regarding genera richness for biotope, we identified 24 genera (11 exclusive) at streams and 14 (only one exclusive) at channel Iguatemi River.Thirteen genera were common in both biotopes.
Although it has been recorded 25 Odonata genera for the Iguatemi River basin, which is considered a good representativeness for the Mato Grosso do Sul State (as discussed earlier), the genus accumulation curve has predicted an increase of new genera.These results, combined with the estimated richness, showed the upward trend in the number of genera with increasing sampling effort.Thereby, conducting long-term studies associated with different types of environments and sampling methods may result in a promising increase of genera, since many genera not yet recorded for the Mato Grosso do Sul State, are known in Brazil.

Conclusion
The results evidenced that the Iguatemi River basin encompasses a highly diverse Odonata fauna.The records of new genres for the state suggests that the Odonata fauna of the study area deserves attention and point to the interest in implementing future areas in the southern Mato Grosso do Sul State.