Checklist of Odonata ( Insecta ) in the state of Rio Grande do Sul , Brazil with seven new records

The regional knowledge of species diversity and distribution is important to support conservation strategies for species and their habitats. The main goal of this work is to present a checklist of Odonata species in the state of Rio Grande do Sul, as well as their known locations in the municipalities. The preparation of the list was based in data gathered from collections of Museu de Ciências da Universidade do Vale do Taquari (UNIVATES), Laboratório de Ecologia e Evolução da Universidade do Vale do Taquari (UNIVATES), Museu de Ciências Naturais da Fundação Zoootânica, Museu de Zoologia da Universidade do Vale do Rio dos Sinos (UNISINOS) plus data extracted from 65 publications and the sites SpeciesLink, All Odonata and Puget Sound University. A total of 182 Odonata species were recorded, spanning nine families and 57 genera. The most representative family was Libellulidae (80 species) followed by Coenagrionidae (41 species) and seven species are new records for Rio Grande do Sul. The list of species presented here is a significant advance compared to previous counts for Rio Grande do Sul, however, our list is by no means a final one. Some regions of the state remain poorly explored, such as the border to Uruguay also in the northernmost part of the state. Several families remain poorly sampled, especially those that inhabit small forested streams and probably there are many specimens which are not cataloged and identified yet in scientific collections, both in the state and in the country.


Introduction
Damselflies and dragonflies are a small group of aquatic insects classified as Odonata, which includes about 6280 species (Schorr & Paulson 2018).This order is spread in temperate, tropical and subtropical zones, with more than 600 genera and 39 families belonging to three suborders: Anisoptera, Anisozygoptera and Zygoptera (Schorr & Paulson 2018).Neotropical region is one of the most diverse, presenting 1727 species (Von Ellenrieder 2009), of which 854 species, 146 genera and 15 families were recorded in Brazil (data available in Pinto 2018).
The regional knowledge of species diversity and distribution is important to provide numerical data, related closely to the actual species richness and abundance numbers (Costa et al. 2000), and support conservation strategies for species and their habitats.A quick survey on Brazilian studies concerning Odonata fauna reveals punctual works restricted to Southeastern and Mid-West regions, suggesting an unequal distribution of research regarding this group in Brazil (De Marco & Viana 2005).This lack of information is the main dead-lock in the elaboration of faunal status list, as the IUCN Red list, which represents a serious problem for conservation programs in Brazil (Rodrigues & Roque 2017).The states of Goiás, Mato Grosso do Sul, Minas Gerais, São Paulo and Rio de Janeiro already have a list of species.
The state of Rio Grande do Sul, located in southern Brazil, stands out due to its extensive agricultural areas and large industrial parks near to the metropolitan region, which causes the state to face serious environmental problems, resulting in a long list of endangered species.Two biomes are recognized in Rio Grande do Sul: Pampa Biome which cover about 66% of the state's area, and Atlantic Forest covering 29% of the total state area.The Atlantic Forest is among the five main nature hotspots on Earth, given its high biodiversity levels and endemisms.However, it has been subject to big rates of deforestation, what makes it even more vulnerable ecologically.The Pampa Biome which is restricted to Rio Grande do Sul, has the greatest endemism rates among the brazilian biomes (39%).It is also heavily threatened by the expansion of monocultures and the introduction of exotic species, which in turn, led to the complete change of its natural landscapes (Oliveira et al. 2017).
Until now, works have been dedicated to improve the knowledge about Odonata fauna in the state (Consatti et al. 2014, Hanauer et al. 2014, Kittel & Engel 2014, 2016, Renner et al. 2013, 2015, 2016, 2017), however, such studies are restricted and do not provide information on total number of species.A recent attempt to estimate the diversity of the state (Kittel & Engel 2014, 2016) recorded 108 species of Odonata, representing about 12% of the known species for Brazil (Pinto 2018), though the authors suggest that this number is much higher.Thus, the main goal of this work is to present the species diversity of Odonata (Insecta) in the state of Rio Grande do Sul, as well as their known locations in the municipalities.

Study area
The state of Rio Grande do Sul, which is located in southernmost portion of Brazil, borders the state of Santa Catarina to the North, the Atlantic ocean to the East, Uruguay to the South and Argentina to the West.With a total area of 281,730 km², it covers the two subtropical biomes of Brazil: Atlantic Forest and Pampa.It presents, mostly, low relief, with 70% of its territory presenting less than 300m of altitude.The highest portion, of more than 600m altitude, is located in the Northeast, comprising 11% of the total surface.Two climatic types characterize Rio Grande do Sul: the humid subtropical climate (Cfa), with well distributed rainfall and hot summers, presenting average annual temperature between 18º and 20ºC, and the oceanic climate (Cfb), also with well distributed rains, but with mild summers, presenting an annual average temperature between 13º and 17ºC (Kuinchtner & Buriol, 2001).
The subtropical Atlantic Forest is located in the North and East half of the state, with an area of 103,505 km², which corresponds to 37% of the total area of the state, and 1.54% of the total area of Brazil.The dominance of the Atlantic Forest in Rio Grande do Sul consists of dense ombrophylous forest, mixed ombrophylous forest (Araucaria forest), semideciduous seasonal forest, altitude and 'restinga' fields (Marcuzzo et al. 1998).These subdivisions result from the great variation of altitude and climatic characteristics.In Rio Grande do Sul, there is an extremely rugged relief, between 0m and 1200m altitude.The climate presents well defined seasons of the year, and its vegetation is characterized by tall trees of broad crown in the upper stratum and by broad-leaved shrubs in the lower stratum.
The Pampa biome, located in the South and West half of the state (57° to 63° W and 34° to 30° S), presents 178,243 km² of total area, corresponding to 63% of the state territory and 2.07% of the Brazilian territory (Crawshaw et al. 2007).The relief in the southern fields is gently undulating, between 500m and 800m of altitude.Plains predominate, but some hills, in the region known as "coxilhas", may be found.Besides the coxilhas, there are also some plateaus.The climate presents the four seasons of the year well defined, and its vegetation is characterized by the presence of grasses, ground plants, shrubs and small trees.

Elaboration of the list
For the preparation of the list, we gathered data from collections of the Museu de Ciências da Universidade do Vale do Taquari (UNIVATES), Laboratório de Ecologia e Evolução da Universidade do Vale do Taquari (UNIVATES) concerning 39 municipalities.All these specimens were preserved in 96% ethanol, and later determined to species level according to Garrison et al. (2006Garrison et al. ( , 2010)), Heckman (2006Heckman ( , 2010) ) and Lencioni (2006).In addition, data were collected from 65 publications, from 1909 to 2018, of the material cataloged in the Museu de Ciências Naturais da Fundação Zoootânica, Museu de Zoologia da Universidade do Vale do Rio dos Sinos (UNISINOS) and the sites SpeciesLink, All Odonata and Puget Sound University.In total, data were collected from 85 localities (Figure 1, Table 1) and 74 data sources.For systematic classification, we followed Dijkstra et al. (2013Dijkstra et al. ( , 2014)).

Results
The total number of Odonata species recorded for Rio Grande do Sul is 182 (Table 2).Additionally, there are five species cited by Kittel and Engels (2014)  Heteragrion ictericum Williamson, 1919 (Heteragrionidae) known only from Amazonian Biome and Teinopodagrion meridionale De Marmels, 2001 (Megapodagrionidae) also cite by Marins et al. (2005), however this species is not recorded from Brazil, just from to mountainous and cloud forest of Andes (IUCN Red List 2018).Both studies didn't cite the source of the information, so we decide to not add these species to final checklist to avoid mistakes.
The total number of genera recorded for the state is 57, distributed in nine families.Libellulidae is the family with the highest number of records, with 22 genera and 80 species, followed by Coenagrionidae with 13 genera and 41 species.Aeshnidae with nine genera and 20 species, and Gomphidae with seven genera and 18 species.Other families recorded are: Corduliidae (one genera, three species), Calopterygidae (two genera, seven species), Heteragrionidae (one genera, three species), Lestidae (one genera, nine species), Megapodagrionidae (one genera, one species).

Discussion
The 182 species listed from RS representing about 22% of the species known to occur in Brazil (Pinto 2018).This number increases the species records for the state by 73% (Kittel & Engels 2014, 2016).Odonata fauna of Rio Grande do Sul is similar to the known fauna, published in species lists, of other states.Rio de Janeiro and São Paulo are the states with the highest number of records, presenting 251 and 280 species respectively (Costa & Santos 2000, Costa et al. 2000).Minas Gerais recorded 218 species (Machado 1998), Mato Grosso do Sul recorded 199 species (Koroiva et al. 2017, Rodrigues & Roque 2017) and Goiás, 152 species (Nóbrega & De Marco 2011).
The list of species presented here represents a significant advance compared to previous counts for Rio Grande do Sul, however, our list is by no means a final one.Some regions of the state remain poorly explored, such as southernmost parts, in cities bordering Uruguay, such as Jaguarão or Santa Vitória do Palmar, or even in the northernmost part of the state (Figure 1).Several families remain poorly sampled, especially those that inhabit small forested streams, such as Corduliidae, Heteragrionidae or Megapodagrionidae, and probably there are many specimens which are still not cataloged and identified in scientific collections, both in the state and in the country.4; 10; 15; 16; 20; 31; 35; 43; 54; 59; 60; 63; 65; 66; 71; 72 We found seven species that had not yet been recorded for Rio Grande do Sul.Erythemis credula, Erythrodiplax avittata and Progomphus intricatus were recorded for native areas of coastal plain of RS.The coastal plain is the region which suffers the most due to the advance of urbanization, and protected areas are scarce in this region too.All species were recorded in places with high degree of preservation, as Erythrodiplax avittata sampled in Itapeva Conservation Unit.Lestes dichrostigma, Oxyagrion sulmatogrossense and Nephepeltia berlai were recorded on montane forest (600 m), in the center-east portion of state (Perau de Janeiro, Arvorezinha, Anta Gorda).Lastly, Oxyagrion chapadense was recorded for seven municipalities of the Pampa bioma (see Table 2).These new records emphasize the need of faunal studies for the state and remark the risk of species loss due to the reduction of natural areas and the lack of areas under protection.
In the list, we verified the presence of one species mentioned as endemic to the Pampa biome Cyanallagma bonariensis (Ris, 1918).Until recently, there was no record of this species for Brazil, only for localities in Argentina and Uruguay.However, Pires et al. (2018), in a recent work about future climate changes on species distribution in Pampa region, also made its first record, which confirms its endemism for the Pampa region.Cyanallagma corbeti described in 2009 by Costa, Santos & Souza occurred only in high altitude fields of São Francisco de Paula and Bom Jesus, being probably endemic from this region.We detected also that some species mentioned as endemic of Pampa biome, were found in Atlantic forest as well, such as Tibiagomphus noval (Rodrigues, 1985) and Castoraeschna decurvata Dunkle & Cook, 1984(Pires et al., 2018).
In conclusion, the order Odonata in Rio Grande do Sul State still needs special attention, mostly in non-explored parts of the Pampa Biome and Seasonal forest.These biomes are under intense pressure and species may quickly disappear.Additionally, for most species, the conservation status is not known (IUCN Red List 2018), which makes it difficult to adopt environmental policies.Thus, we highlight the need of information regarding diversity, distribution, biogeography and ecology of species since biodiversity inventories play a key role in the development of conservation strategies (Renner et al. 2017).

Table 1 .
Numbers and codes for municipalities and references.*Municipalities sampled by Laboratório de Ecologia e Evolução -UNIVATES.

Table 2 .
Species recorded for Rio Grande do Sul State, Brazil.For references and municipalities codes, please check Table1.