Abstract:

Here we present the first Odonata (Insecta) species list for the state of Acre, Northern Brazil, adding ecological aspects and notes on its taxonomy and conservation status. Regarding Odonata samplings, Acre is one of the least explored states in the northern region of Brazil and an area of geographic importance, as it is a transition between the Andean and Amazon regions. Collections were carried out in 35 streams, distributed in nine municipalities. We also supplemented our database from the review of secondary literature and data from biological collections. We recorded 140 species, distributed in 55 genera, of which 16 species are new records for the state, making Acre state the second in the number of recorded species in northern Brazil. Of the recorded species, 113 are classified within some threat category of the IUCN red list and 110 in the ICMBio national list. Analyzing the taxonomic information on each recorded species, knowledge of females and larvae is still very limited and, most of the time, only available to adult males. For the first time, the occurrence of Drepanoneura loutoni von Ellenrieder & Garrison (2008)ELLENRIEDER, N.V. & GARRISON, R.W. 2008. Drepanoneura gen. nov. for Epipleoneura letitia and Protoneura peruviensis, with descriptions of eight new Protoneuridae from South America (Odonata: Protoneuridae), Zootaxa,1842, 1-34. is reported for Brazil, and we also present photos of its main morphological characters, with comments on its biology. Our study shows the importance of conducting biodiversity research in poorly studied areas; such as the state of Acre, and serves as a basis for future expeditions in the region.

Keywords:
List of distribution; Aquatic insects; Inventory; Anisoptera and Zygoptera

Resumo:

Apresentamos a primeira lista de espécies de Odonata (Insecta) para o estado do Acre no Brasil, adicionando aspectos ecológicos e notas sobre o seu estado de conservação. O Acre é um dos estados com o menor esforço de coleta da região Norte do Brasil e uma área de importância geográfica, pois é uma transição entre os Andes e a Amazônia. Foram realizadas coletas em 35 riachos, distribuídos em nove municípios e também complementados com informações de dados secundários de revisão na literatura e bases de dados de coleções biológicas. Registramos 140 espécies, distribuídas em 55 gêneros, das quais 16 espécies são novos registros para o estado, tornando-o o segundo em número de espécies na região Norte do Brasil. Das espécies registradas, 113 estão classificadas dentro de alguma categoria de ameaça da lista vermelha da IUCN e 110 na lista nacional do ICMBio. Analisando as informações do conhecimento das espécies, o conhecimento das fêmeas e larvas ainda muito limitado e na maioria das vezes disponíveis apenas para os machos adultos. Pela primeira vez é registrada a ocorrência da Drepanoneura loutoni von Ellenrieder & Garrison (2008)ELLENRIEDER, N.V. & GARRISON, R.W. 2008. Drepanoneura gen. nov. for Epipleoneura letitia and Protoneura peruviensis, with descriptions of eight new Protoneuridae from South America (Odonata: Protoneuridae), Zootaxa,1842, 1-34. no Brasil, também apresentamos fotos das principais estruturas, com comentários sobre sua biologia. Nosso trabalho mostra a importância da realização de estudos de biodiversidade em áreas ainda pouco estudadas como a do estado do Acre e serve como base para futuras expedições na região.

Palavras-chave:
Lista de distribuição; Insetos aquáticos; Inventário; Anisoptera e Zygoptera

Introduction

Dragonflies and damselflies (order Odonata) constitute a group of charismatic insects, with vibrant colors and great flight capacity (Souza et al. 2007SOUZA, L.O.I., COSTA, J. M. & OLDRINI, B. B. 2007. Odonata. In: Guia on-line: Identificação de larvas de Insetos Aquáticos do Estado de São Paulo. Froehlich, C.G. (org.). http://sites.ffclrp.usp.br/aguadoce/Guia_onlin (last access in 10/03/2021)
http://sites.ffclrp.usp.br/aguadoce/Guia... ). Worldwide, there are more than 6,300 Odonata valid species, however, considering the great diversity that has yet to be described, estimates indicate that the real number could exceed 7,000 (Suhling et al. 2015SUHLING, F. 2015. Thorp and Covich’s Freshwater Invertebrates || Order Odonata, cap. 35, 893-932., Bybee et al. 2021BYBEE, S.M., KALKMAN, V.J., ERICKSON, R.J., FRANDSEN, P.B., BREINHOLT, J.W., SUVOROV, A., DIJKSTRA, K.D.B., CORDERO-RIVERA, A., SKEVINGTON, J.H., ABBOTT, J.C., HERRERA, M.S., LEMMON, A.R., LEMMON, E.M. & WARE, J.L. 2021. Phylogeny and classification of Odonata using targeted genomics. Mol. Phylogenet. Evol. 160, 107-115.), due to the preservation of environmental conservation areas focused on these organisms (Bede 2015BEDE, L.C., MACHADO, A.B.M, PIPER, W., & SOUZA, M.M. 2015. Odonata of the Serra de São José - Brazil’s first Wildlife Reserve aimed at the conservation of dragonflies. Notulae odonatologicae 8(5) 117-155.). The Neotropical region alone contributes approximately 1,700 of the described species (Olaya 2019OLAYA, M. 2019. Odonatos en Latinoamérica: la riqueza de nuestra región. Hetaerina. 1(2):4-5.). In this region, South America stands out for its high species richness, althought much of its territorial extension has not yet been satisfactorily sampled (Kalkman 2008KALKMAN, V.J., CLAUSNITZER, V., DIJKSTRA, K.D.B., ORR, A.G., PAULSON, D.R. & VAN TOL, J. 2008. Global diversity of dragonflies (Odonata) in freshwater. Hydrobiologia, 595 (1), 351-363., Araújo et al. 2020ARAÚJO, M.F.A., DE MARCO JR., P., JUEN, L. & TÔRRES, L.M. 2020. Vulnerability of Phyllocycla species (Odonata: Gomphidae) to current and Planned Anthropic Activities by the Brazilian Government. Neotrop. Entomol., 49, 24-32.). This is an even more evident problem in countries with a large territorial extension such as Peru, Colombia or Brazil (Tognelli et al. 2016TOGNELLI, M.F., LASSO, C.A., BOTA-SIERRA, C.A., JIMÉNEZ-SEGURA, L.F. & COX, N.A. 2016. Estado de Conservación y Distribución de la Biodiversidad de Agua Dulce en los Andes Tropicales. Gland, Suiza, Cambridge, UK y Arlington. 199.).

In Brazil, 901 species of dragonflies are recorded (Pinto 2021PINTO, A.P. 2021. Odonata in Catálogo Taxonômico da Fauna do Brasil. http://fauna.jbrj.gov.br/fauna/listaBrasil (last access in 12/04/2021).
http://fauna.jbrj.gov.br/fauna/listaBras... ), a number that reflects the growing number of studies with this target group in the last decade (Miguel et al. 2017MIGUEL, T.B., OLIVEIRA-JUNIOR, J.M.B., LIGEIRO, R. & JUEN, L. 2017. Odonata (Insecta) as a tool for the biomonitoring of environmental quality. Ecol. Indic. 81, 555-566.). Despite this increase, only 29% of the Brazilian territory was surveyed so far, being a large part of these collections carried out in regions with more human and financial resources, such as the Southern, Southeastern and Midwestern regions (De Marco & Vianna 2005DE MARCO, P.J.R. & VIANNA, D.M. 2005 Distribuição do esforço de coleta de Odonata no Brasil - subsídios para escolha de áreas prioritárias para levantamentos faunísticos. Int. J. of Biodiver., 6(sup.), 13-26. Distribution of Odonata sampling effort in Brasil - basis for choosing prioritary áreas for faunistic inventories. Int. J. Biodivers. Sci. Gerenciar. 6, 13-26., Calvão et al. 2016CALVÃO, LB, NOGUEIRA DS, DE ASSIS MONTAG L.F., LOPES M.A. & JUEN, L. 2016. Are Odonata communities impacted by conventional or reduced impact logging? For. Ecol. Manage. 382: 143-150., Rodrigues & Roque 2017RODRIGUES, M.E. & ROQUE, F.O. 2017. Checklist de Odonata do Estado de Mato Grosso do Sul, Brasil. Iheringia, Série Zoologia, 107(supl.): e2017117.). In this sense, these studies, in addition to being insufficient, have a heterogeneous spatial distribution with a recent and slow increase in poorly sampled areas and which access is difficult, such as the Northern, (Koroiva et al. 2020aKOROIVA, R., BRASIL, P.G., NEISS, U.G., VILELA, D.S. & HAMADA, N. 2020a. Dragonflies and damselflies (Insecta: Odonata) housed in the Invertebrate Collection of the Instituto Nacional de Pesquisas da Amazônia, Brazil. Hetaerina. Vol. 2 (2): 14-23., Garcia Junior et al. 2021GARCIA JUNIOR, M.D.N., DAMASCENO, M.T.S., MARTINS, M.J.L., COSTA, T.S., FERREIRA, R.M.A. & SOUTO, R.N.P. 2021. New records of dragonflies and damselflies (Insecta: Odonata) from Amapá state, Brazil. Biota Neotrop, 21(1). https://doi.org/10.1590/1676-0611-BN-2020-1074
https://doi.org/10.1590/1676-0611-BN-202... ) and Northeastern regions (Santos et al. 2021SANTOS, E.L., ABREU, V.S., MIRANDA, E.N., LOPES, I.L., GAMA, L.E.S., SANTOS, N.P., BRUM, D.L., BERG, E.V.D., FARIAS, J.F. & RODRIGUES, E.S. 2021. Silvicultura e Manejo Florestal Técnicas de Utilização e Conservação da Natureza. Editora cientifica digital. 1 (25), 330-343., Koroiva et al. 2021KOROIVA, R., PEREIRA-COLAVITE, A., BATISTA, F.R.C. & VILELA, D.S. 2021. Checklist and contribution to the knowledge of the odonatofauna of Paraíba state, Brazil. Biota Neotrop. 21(3): e20211196. https://doi.org/10.1590/1676-0611-BN-2021-1196 (last access in 16/12/2021)
https://doi.org/10.1590/1676-0611-BN-202... ).

Acre is one of the nine states that compose the Brazilian Legal Amazon (Padrão et al. 2016PADRÃO, G.A., Lirio, V.F. & LIMA, J.E. 2016. Determinantes do desmatamento na Amazônia Legal: um estudo de caso do estado do Acre. Revista de Administração e Negócios da Amazônia, 8 (1), 85-108.), a region with large knowledge gaps, especially those related to which species exist and where they are distributed (Linnean and Wallacean gaps) (Hortal et al. 2015HORTAL, J., BELLO, F., DINIZ-FILHO, J.A.F., LEWINSOHN, T.M., LOBO, J.M. & LADLE, R.J. 2015. Seven Shortfalls that Beset Large-Scale Knowledge of Biodiversity. The Annual Rev.iew of EntomolEcology, Evolution, and Systematics is online at ecolsys. 46:523-49). So far, there are only studies by Raimundo et al. (2003)RAIMUNDO, R.L.G., FREITAS, A.V.L., COSTA, R.N.S., DE OLIVEIRA, J.B.F., LIMA, A.F., MELO, A.B. & BROWN JR, K.S. 2003. Manual de monitoramento ambiental usando borboletas e libélulas - Reserva Extrativista do Alto Juruá. UNICAMP, (1), 36., Oliveira (2017)OLIVEIRA, S.A.V. 2017. Composição e similaridade de espécies de Odonata em dois ambientes lóticos no complexo vegetacional sobre areia branca, Acre. In Complexo vegetacional sobre areia branca: campinaranas do sudoeste da Amazônia. Universidade Federal do Acre - Rio Branco: Edufac. and Garcia Junior et al. (2022)GARCIA JUNIOR, M.D.N., DAMASCENO, M.T.S., VILELA, D.S. & SOUTO, R.N.P. 2022. The Brazilian Legal Amazon Odonatofauna: a perspective of diversity and knowledge gaps. Ento. Brasilis. 15: e977. dealing with Odonata species for the state, none of which are specifically directed to the state of Acre in order to list records. However, research carried out in the vicinities of Acre (e.g., state of Amazonas) provides an idea of the diversity potential existing in the region. For example, Paulson (1985)PAULSON, D.R. 1985. Odonata of the Tambopata Reserved Zone, Madre de Dios, Peru. Rev.ista Peru.ana de Entomologia. 27: 9-14 cites the Manu National Park (Perú) as one of the most biodiverse regions for dragonflies on the planet, with 838 species recorded, corresponding to approximately 13% of the global Odonatofauna (reinforced by Venable 1996VENABLE, G.L., & ERWIN, T.L. 1996. Mapping of the biodiversity site at Pakitza. Pp. 29-42, in Manu: The biodiversity of Southeastern Peru (D.E. Wilson and A. Sandoval, eds.). Smithsonian Institution Press. 679.). Additionally, in Northern Brazil, 334 species have recorded the state of Amazonas alone, which neighbors the state of Acre (Koroiva et al. 2020bKOROIVA, R., NEISS, U.G., FLECK, G. & HAMADA, N. 2020b. Checklist of dragonflies and damselflies (Insecta: Odonata) of the Amazonas state, Brazil. Biota Neotrop, 20 (1). https://doi.org/10.1590/1676-0611-BN-2019-0877 (last access in 16/12/2021)
https://doi.org/10.1590/1676-0611-BN-201... ). Furthermore, carrying out studies in border regions such as Acre-Pando-Madre de Dios (Brazil, Bolivia and Peru) are of great importance for taking conservation actions for the forest fragments and transboundary water resources (Souza et al. 2013SOUZA, M.M., SOUZA, B., PEREIRA, M.C.S.A & MACHADO, A.B.M. 2013. List of Odonates from Mata do Baú, Barroso, Minas Gerais, Brazil. Journal of species lists and distribution Check List, 9(6), 1367-1370., Acre 2010ACRE, Governo do Estado. 2010. Zoneamento Ecológico-Econômico do Estado do Acre, Fase II (Escala 1:250.000): Documento Síntese. Rio Branco: SEMA, 2, 356.).

Regarding this scenario, the objectives of our study were: i) to provide the first Odonata species list for the state of Acre; and ii) to provide information on the type of environment in which the species were collected and their level of degradation. Additionally, we recorded for the first time to Brazil the specie Dreopanoneura loutoni von Ellenrieder & Garrison, 2008ELLENRIEDER, N.V. & GARRISON, R.W. 2008. Drepanoneura gen. nov. for Epipleoneura letitia and Protoneura peruviensis, with descriptions of eight new Protoneuridae from South America (Odonata: Protoneuridae), Zootaxa,1842, 1-34., providing some taxonomic notes and images for the terminalia of both male and female, as well habitat characteristics. We believe that these results can mitigate some of the Linnean gap still present in this region, and consequently provide basic biological information that can be used in further studies for the Amazon forest.

Material and Methods

1. Study Area

The Acre state is located in the extreme west of the Northern region of Brazil, in the Western Amazon (Brasil 1968BRASIL. DECRETO -LEI DECRETO-LEI Nº 356, DE 15 DE AGOSTO DE 1968. LEX. Presidência da República. Áreas da Amazonia Ocidental e outfras Províncias. Brasília, DF, 1968.). The territorial extension of the state comprises an area of 164,173,431 km², representing 4% of the Brazilian Amazon and 1.9% of the total territory of Brazil (Figure 1) (Acre 2010ACRE, Governo do Estado. 2010. Zoneamento Ecológico-Econômico do Estado do Acre, Fase II (Escala 1:250.000): Documento Síntese. Rio Branco: SEMA, 2, 356., IBGE 2021IBGE - Instituto Brasileiro de Geografia e Estatística: cidades e estados. Brasil: IBGE. Disponível em: https://www.ibge.gov.br/cidades-e-estados/ac/. (last access in 22/09/2021).
https://www.ibge.gov.br/cidades-e-estado... ). The state of Acre has international borders with Peru and Bolivia, and national borders with the states of Amazonas and Rondônia (Acre 2010ACRE, Governo do Estado. 2010. Zoneamento Ecológico-Econômico do Estado do Acre, Fase II (Escala 1:250.000): Documento Síntese. Rio Branco: SEMA, 2, 356.).

The prevailing climate is the “Am” tropical type (according to Köppen’s classification), described as hot and humid, with high temperatures, high levels of rainfall, and high relative humidity (Peel et al. 2007PEEL, M.C., FINLAYSON, B.L. & MCMAHON, T.A. 2007. Updated world map of the Koppen-Geiger climate classification. Hydrol. Earth Syst. Sci. 11(5), 1633-1644.). The Acre soils, of sedimentary origin, have a predominantly dense rainforest cover (SEMA 2021SEMA - Secretaria Estadual do Meio Ambiente do Estado do Acre. http://www.ac.gov.br/wps/portal/acre/Acre/governo-estado/secretarias/ (last access in 26/04/2021).
http://www.ac.gov.br/wps/portal/acre/Acr... ), characterized by floristic heterogeneity, which constitutes great economic value for the state (Acre 2010ACRE, Governo do Estado. 2010. Zoneamento Ecológico-Econômico do Estado do Acre, Fase II (Escala 1:250.000): Documento Síntese. Rio Branco: SEMA, 2, 356.). Regarding the relief, the state of Acre has a stable platform that descends smoothly at 300 m on international borders to just over 110 m on the limits with the state of Amazonas. At the western end is the highest point in the state, where the relief changes with the Serra do Divisor, a branch of the Serra Peruana de Contamana, with maximum altitude of 734 m. The hydrography is quite complex, being formed by the hydrographic basins of the rivers Juruá and Purus, tributaries on the right bank of the Solimões river (Acre 2010ACRE, Governo do Estado. 2010. Zoneamento Ecológico-Econômico do Estado do Acre, Fase II (Escala 1:250.000): Documento Síntese. Rio Branco: SEMA, 2, 356.).

The Acre state falls under the Amazon deforestation arc, where approximately 11% of its territory was already deforested due to the advance of agricultural frontiers (Aguiar et al. 2016AGUIAR, S., SANTOS, I.S., ARÊDES, N. & SILVA, S. 2016. Redes-Bioma: Informação e comunicação para ação sociopolítica em eco regiões. Ambient. soc., 19(3), 233-252.). Furthermore, that region is characterized by extractive activities such as rubber and Brazil nut extraction (Ângelo et al. 2013ANGELO, H., POMPERMAYER, R.S., ALMEIDA, A.N. & MOREIRA, J.M.A.P. 2013. O custo social do desmatamento da Amazônia brasileira: o caso da castanha-do-brasil (Bertholletia excelsa). Cienc. Florestal. 23 (1), 183-191., Martins 2020MARTINS, W.B.R. 2020. Restauração de ecossistemas degradados pela mineração na Amazônia Oriental. Tese de Doutorado. Universidade Federal Rural da Amazônia, Belém,). However, activities such as the reforestation of Teak (Tectona grandis L. F.), fire control programs in the region (large contributors to the ecological imbalance of forests), and monitoring activities (Raimundo et al. 2003RAIMUNDO, R.L.G., FREITAS, A.V.L., COSTA, R.N.S., DE OLIVEIRA, J.B.F., LIMA, A.F., MELO, A.B. & BROWN JR, K.S. 2003. Manual de monitoramento ambiental usando borboletas e libélulas - Reserva Extrativista do Alto Juruá. UNICAMP, (1), 36., Terra 2017TERRA, G. 2017.Efetividade da Fiscalização do Desmatamento Ilegal nas Unidades de Conservação Federais no Estado do Acre. INPA. MPGAP.) are preserving native species in the state.

1.1 Places Sampled on Excursions

The sampling was made in the municipalities of Assis Brasil, Brasiléia, Porto Acre, Rio Branco, Sena Madureira, and Senador Guiomard (TABLE 1). The sampled municipalities correspond to approximately 22% of the total area of the state (IBGE 2021IBGE - Instituto Brasileiro de Geografia e Estatística: cidades e estados. Brasil: IBGE. Disponível em: https://www.ibge.gov.br/cidades-e-estados/ac/. (last access in 22/09/2021).
https://www.ibge.gov.br/cidades-e-estado... ). We selected streams that represent a wide gradient of forest cover at the landscape level, and different land uses, from areas altered by agriculture and pasture, to preserved areas located within conservation units. There are two extractive reserves among the sampled areas: RESEX Chico Mendes and RESEX Cazumbá-Iracema, both conservation units meant for sustainable use of natural resources. Data from the RESEX Alto Juruá, taken from the secondary database (Raimundo et al. 2003RAIMUNDO, R.L.G., FREITAS, A.V.L., COSTA, R.N.S., DE OLIVEIRA, J.B.F., LIMA, A.F., MELO, A.B. & BROWN JR, K.S. 2003. Manual de monitoramento ambiental usando borboletas e libélulas - Reserva Extrativista do Alto Juruá. UNICAMP, (1), 36.), were also used. The territorial extension of RESEX Chico Mendes is 970,570 acres, while in Cazumbá-Iracema the territory is 750,795 acres (Acre 2010ACRE, Governo do Estado. 2010. Zoneamento Ecológico-Econômico do Estado do Acre, Fase II (Escala 1:250.000): Documento Síntese. Rio Branco: SEMA, 2, 356.). Even located within conservation units, these areas are under strong anthropogenic pressure, especially from activities with high environmental impact, such as the conversion of forest into pasture for cattle raising (Fantini & Crisóstomo 2009FANTINI, A.C. & CRISÓSTOMO, C.F. 2009. Conflitos de interesse em torno da exploração madereira na Reserva Extrativista Chico Mendes, Acre, Brasil. Bol. do Mus. Para. E. Goeldi. Ciências Humanas, 4(2), 231-246., Mascarenhas et al. 2018MASCARENHAS, F.S., BROWN, I.F., & SILVA, S.A. 2018. Desmatamento e incêndios florestais transformando a realidade da Reserva Extrativista Chico Mendes. Desenvol. e Meio Ambiente. 48, 236-262.). All collections were made with permission from the Biodiversity Authorization and Information System - SISBio (License number: 11841-4).

The Habitat Integrity Index (HII) (Nessimian et al. 2008NESSIMIAN, L.J., VENTICINQUE, E.M., ZUANON, J., MARCO JR, P., GORDO, M., FIDELIS, L., BATISTA, J.D. & JUEN, L. 2008. Land use, habitat integrity, and aquatic insect assemblages in Central Amazonian streams. Hydrobiologia, v 614, n 117.614: 117-131.) was used to relate the integrity of sampled sites to the presence of species. This index has been shown to be an effective metric to explain the distribution of aquatic insect communities, mainly Odonata (Brasil et al. 2021BRASIL, LS., ANDRADE, AFA, RIBEIRO, BR, SPIGOLONI, ZA, JUEN, L. & DE MARCO, P. 2021. A niche-based gap analysis for the conservation of odonate species in the Brazilian Amazon. Aquat. Conserv. Mar. Freshwater Ecosyst. 31(5), 1150-1157.). The index consists of 12 items, which assess characteristics of the banks and the water body. The result varies between 0 (degraded) and 1 (preserved). To categorize the streams, we adopted the criterion proposed by Oliveira-Junior (2015)OLIVEIRA- JUNIOR, J.M.B. 2015. Estruturação da comunidade de odonata (insecta) na Amazônia Oriental: efeitos espaciais, ambientais e morfológicos em igarapés íntegros. 148 f. Tese (Doutorado) - Universidade Federal do Pará, Museu Paraense Emílio Goeldi, Instituto de Ciências Biológicas, Belém. Programa de Pós-Graduação em Zoologia. Disponível em: <http://repositorio.ufpa.br/jspui/handle/2011/9408>. Acesso em: 16/12/2021
http://repositorio.ufpa.br/jspui/handle/... , where environments are considered degraded when values are between 0.15 < HII < 0.49; intermediate if 0.5 < HII < 0.74; and preserved if HII > 0.75. This classification criterion has been used successfully in other research (Monteiro-Junior et al. 2015MONTEIRO JÚNIOR, C.S., JUEN, L. & HAMADA, N. 2015. Analysis of urban impacts on aquatic habitats in the central Amazon basin: Adult odonates as bioindicators of environmental quality. Ecol. Indic. 48, 303-311., Oliveira-Junior 2015OLIVEIRA- JUNIOR, J.M.B. 2015. Estruturação da comunidade de odonata (insecta) na Amazônia Oriental: efeitos espaciais, ambientais e morfológicos em igarapés íntegros. 148 f. Tese (Doutorado) - Universidade Federal do Pará, Museu Paraense Emílio Goeldi, Instituto de Ciências Biológicas, Belém. Programa de Pós-Graduação em Zoologia. Disponível em: <http://repositorio.ufpa.br/jspui/handle/2011/9408>. Acesso em: 16/12/2021
http://repositorio.ufpa.br/jspui/handle/... , Oliveira-Junior & Juen 2019OLIVEIRA-JUNIOR, J.M.B. & JUEN, L. 2019. The Zygoptera/Anisoptera ratio (Insecta:Odonata): A new tool for habitat alterations assessment in Amazonian streams. Neotrop. entomol. 48 (4), 552-560.) (Table 1).

2. Preparation of Species List

The preparation of the species list was made using information from primary data (expeditions and field data collection in 35 streams) and secondary data (from literature and databases). To prepare the list, this information was gathered together with information from the Odonata collection of the Laboratory of Ecology and Conservation (LABECO) of the Federal University of Pará (UFPA), Belém (for more details on the database, access Brasil et al. 2021BRASIL, LS., ANDRADE, AFA, RIBEIRO, BR, SPIGOLONI, ZA, JUEN, L. & DE MARCO, P. 2021. A niche-based gap analysis for the conservation of odonate species in the Brazilian Amazon. Aquat. Conserv. Mar. Freshwater Ecosyst. 31(5), 1150-1157.).

2.1 Collection of Specimens

Adult odonates were collected from 35 small streams (1st to 3rd order according to the Strahler’s classification (1957)STRAHLER, A.N. 1957. Quantitative analysis of watershed geomorphology. Trans., Am. Geophy. Union. 38(6), 913-920.). A transect of 150 meters was established in each stream, and then subdivided into ten longitudinal sections of 15 m each, named “A” to “K” in the upstream direction. In addition, specimens were collected more specifically on the banks of the stream, with the aid of an entomological net and with a sampling effort of one hour along each transect, with an average of six minutes on each longitudinal section (Cezário et al. 2021CEZÁRIO, R.R., FIRME, P.P., PESTANA, G.C., VILELA, D.S., JUEN, L., CORDERO-RIVERA, A. & GUILLERMO, R. 2021. Sampling Methods for Dragonflies and Damselflies. In: Santos J.C., Fernandes G.W. (eds) Measuring Arthropod Biodiversity. Springer, Cham. 978-3-030-53225-3.). Sampling was always carried out on sunny days between 11:00 and 14:00, which is the ideal weather conditions for the activity of most Odonata species (Monteiro-Júnior et al. 2015MONTEIRO JÚNIOR, C.S., JUEN, L. & HAMADA, N. 2015. Analysis of urban impacts on aquatic habitats in the central Amazon basin: Adult odonates as bioindicators of environmental quality. Ecol. Indic. 48, 303-311., Oliveira-Junior & Juen 2019OLIVEIRA-JUNIOR, J.M.B. & JUEN, L. 2019. The Zygoptera/Anisoptera ratio (Insecta:Odonata): A new tool for habitat alterations assessment in Amazonian streams. Neotrop. entomol. 48 (4), 552-560.). The collected specimens were packaged and preserved according to the protocol by Lencioni (2006)LENCIONI, F.A.A 2006. Damselflies of Brazil, an illustrated indentification guide: II - Coenagrionidae families. São Paulo: All Print. 419 pp.. For the taxonomic identification of the collected specimens, specific keys such as those by Lencioni (2005LENCIONI, F.A.A 2005. Damselflies of Brazil, an illustrated indentification guide: I - The non-Coenagrionidae families. São Paulo: All Print. 324 pp., 2006LENCIONI, F.A.A 2006. Damselflies of Brazil, an illustrated indentification guide: II - Coenagrionidae families. São Paulo: All Print. 419 pp., 2013)LENCIONI, F.A.A 2013. Diagnoses and discussion of the group 1 and 2 Brazilian species of Heteragrion, with descriptions of four new species (Odonata: Megapodagrionidae). Zootaxa 3685(1): 001-080., and Garrison et al. (2006)GARRISON, R.W., ELLENRIEDER, N.V. & LOUTON, J.A. 2006. Dragonfly genera of the New World An illustrated and annotated key to the Anisoptera. Baltimore: The Jonhs Hopkins University Press. 368 pp. were used. In addition, comparisons were made with specimens already identified and deposited in the collection of LABECO - UFPA, and, when necessary, specialists were consulted, such as Frederico Lencioni e Diogo Vilela.

2.2 Search in Literature and Databases

Additional secondary data were obtained from the following databases: SpeciesLink (http://splink.Cria.org.br/), and Brazilian Taxonomic Catalog of FaunaBRAZILIAN TAXONOMIC CATALOG OF FAUNA. http://fauna.jbrj.gov.br/fauna/listaBrasil/ConsultaPublicaUC/ConsultaPublicaUC.do (last access in 24/02/2022).
http://fauna.jbrj.gov.br/fauna/listaBras... (http://fauna.jbrj.gov.br;Brazilian FaunaTaxonomic Catalog), making a filter for information on species in the state of Acre. Data was also gathered from specimen description studies, mainly seeking information from biology or natural history and where they occur in Brazil (Garrison et al. 2006GARRISON, R.W., ELLENRIEDER, N.V. & LOUTON, J.A. 2006. Dragonfly genera of the New World An illustrated and annotated key to the Anisoptera. Baltimore: The Jonhs Hopkins University Press. 368 pp., Lencioni 2005LENCIONI, F.A.A 2005. Damselflies of Brazil, an illustrated indentification guide: I - The non-Coenagrionidae families. São Paulo: All Print. 324 pp., 2006LENCIONI, F.A.A 2006. Damselflies of Brazil, an illustrated indentification guide: II - Coenagrionidae families. São Paulo: All Print. 419 pp.). With the incorporation of secondary data, we added 12 more collection points in six municipalities, taken from the literature describing the corresponding species, three exclusively for literature data and another three already added from LABECO collection tours, data from two recently published articles were also incorporated, Oliveira (2017)OLIVEIRA, S.A.V. 2017. Composição e similaridade de espécies de Odonata em dois ambientes lóticos no complexo vegetacional sobre areia branca, Acre. In Complexo vegetacional sobre areia branca: campinaranas do sudoeste da Amazônia. Universidade Federal do Acre - Rio Branco: Edufac. as point L14 and Garcia Junior et al. (2022)GARCIA JUNIOR, M.D.N., DAMASCENO, M.T.S., VILELA, D.S. & SOUTO, R.N.P. 2022. The Brazilian Legal Amazon Odonatofauna: a perspective of diversity and knowledge gaps. Ento. Brasilis. 15: e977. as point L13 (TABLE 2). The literature search was based on the Web of Science and Scielo databases, using data from previously published studies that record odonates in the region of the Acre state. The published data are also search results on Google Scholar (http://scholar.google.com), we use the terms: “Odonata and Acre and Brasil” for more general literature, and we add specific terms to confirm information missing (e.g. “larva and female” or “taxonomy and description”). There have been species description works since the end of the 18th century and the beginning of the 19th century, with specimens of odonatas collected in the region of the state. Searches were carried out in May 2021. Additional searches were completed in February 2022. Collection information was considered: species name, occurrence, collection date, collector name and location (city and state), in addition to additional information about the altitude level of each point, habitat (municipality and additional information such as vegetation type or name of stream or lake, when available), number of individuals collected and number of males, females and larvae described.

3. Statistical Analysis

To assess the efficiency of the sampling effort, we generated collector curves with rarefaction (interpolation) using the first-order Jackknife estimator, which allows us to evaluate collection efficiency and produce the collector curve. Using this method, we estimated the number of species per sampled transect. As a result, the observed richness with the average of Mao Tau Sobs was obtained and Jackknife (Burnham & Chazdon 1978; Burnham & Overton 1979BURNHAM, K.P. & OVERTON, W.S. 1979. Robust estimation os population size when capture probabilities vary among animals. Ecology. 60:927-936.), the most accurate and least biased estimator compared to other extrapolation methods (Palmer, 1990PALMER, M.W. 1990. The estimator of species richness by extrapolation. Ecology. 71: 1195-1198.). All analyzes were performed in the R software (R Core Team 2019R Core Team. 2019. R: A language and environment for statistical computing. R Foundation for Statistical Computing, https://www.R-project.org/. (last access in 21/04/2021)
https://www.R-project.org/.... ) using the “vegan” (Oksanen et al. 2005OKSANEN, J., BLANCHET, F.G., FRIENDLY, M., KINDT, R., LEGENDRE, P., MCGLINN, D. & WAGNER, H. 200518. Community ecology package. R package version, 2-5. http://sortie-admin.readyhosting.com/lme/R%20Packages/vegan.pdf (last access in 21/04/2022)
http://sortie-admin.readyhosting.com/lme... ), and “BiodiversityR” (Kindt & Coe 2005KINDT, R. & COE, R. 2005. Tree diversity analysis: a manual and software for common statistical methods for ecological and biodiversity studies. World Agroforestry Centre. 8, 137.) packages (^{Supplementary Material} Supplementary Material The following online material is available for this article: Table S1 - Richness estimate performed for each of the sampled points , Table S1).

4. Taxonomic Notes

Drepanoneura loutonivon Ellenrieder & Garrison, 2008ELLENRIEDER, N.V. & GARRISON, R.W. 2008. Drepanoneura gen. nov. for Epipleoneura letitia and Protoneura peruviensis, with descriptions of eight new Protoneuridae from South America (Odonata: Protoneuridae), Zootaxa,1842, 1-34. was recorded for the first time in Brazil. D. loutoni were collected in the two extractive reserves (RESEX). The specimens were photographed using a Leica M205 a stereomicroscope equipped with a Leica DFC 450 camera. Subsequently, we processed the image in the in a free image editor. Morphological terminology for D. loutoni follows von Ellenrieder & Garrison (2008)ELLENRIEDER, N.V. & GARRISON, R.W. 2008. Drepanoneura gen. nov. for Epipleoneura letitia and Protoneura peruviensis, with descriptions of eight new Protoneuridae from South America (Odonata: Protoneuridae), Zootaxa,1842, 1-34.. All the measurements are in millimeters (mm). Abbreviations: Ce, cercu; Pa, paraproct; Ep, epiprocto; Tru, truncated.

Results

Altogether, 140 species were recorded (Table 3; Figure 2, 3 and 4), being 57 from primary data and 108 from secondary records, with 19 of these records already in our collection data. The number of estimated species was 38 ± 0.652 (mean ± SD). When we analyzed the efficiency of the collection effort (average observed richness/average estimated richness), we obtained a value of 73%. These results show that the efficiency collection for the study was enough to sample the existing biodiversity in the region. A similar result was observed in the collector curve, where there was a tendency to stabilization in its final part (Figure 5; ^{Supplementary material} Supplementary Material The following online material is available for this article: Table S1 - Richness estimate performed for each of the sampled points , Table S1).

The total number of Odonata genera thus far recorded for the state is 55, distributed in nine families. The suborder Zygoptera was the most representative, with six families, namely: Calopterygidae (two genera, six species), Coenagrionidae (17 genera, 54 species), Heteragrionidae (one genus, three species), Polythoridae (two genera, four species), Dicteriadidae (one genus, one species), Perilestidae (two genera, two species). In its turn, the suborder Anisoptera comprises three families: Libellulidae (23 genera, 62 species), Gomphidae (two genera, two species), and Aeshnidae (five genera, five species).

Of the 140 recorded species, 98 have described females. When considering the larval stages, only 56 species have their larvae described. In our study, the material identified to genus level was not considered, as it could represent an underestimation of the diversity presented here. However, we would like to record the existence of specimens of the following genera: Dythemis Hagen, 1861, Elasmothemis Westfall, 1988, Oligoclada Karsch, 1890, and Heteragrion Selys, 1862 that present different structures. More detailed analyzes are being carried out to determine if these taxa represent species new to science or new records for Brazil.

Knowledge concerning the conservation status of dragonflies in Acre state is still incipient. However, based on the Red List of Endangered Species of the Livro Vermelho da Fauna Brasileira Ameaçada de Extinção (ICMBio 2018LIVRO VERMELHO DA FAUNA BRASILEIRA AMEAÇADA DE EXTINÇÃO.: Volume I / -- 1. ed. -- Brasília, DF: ICMBio/MMA, 2018. https://www.icmbio.gov.br/portal/images/stories/comunicacao/publicacoes/publicacoes-diversas/livro_vermelho_2018_vol1.pdf (last access in 21/04/2022)
https://www.icmbio.gov.br/portal/images/... ) and the International Union for Conservation of Nature (IUCN, https://www.iucnredlist.org), of the 140 listed species, 113 were evaluated, but we emphasize that none is threatened with extinction (EX), in critical danger (CR) or any threat category (TABLE 3). In the IUCN list, most species (103) are in the Least Concern (LC) category, 10 species have insufficient data (DD), while 27 species have not yet been evaluated (NE); on the ICMBio list, 105 species are listed as least concerning (LC), five have insufficient data (DD) and 30 have not yet been evaluated.

The registration data for Brazil come from the taxonomic keys of Lencioni (2005LENCIONI, F.A.A 2005. Damselflies of Brazil, an illustrated indentification guide: I - The non-Coenagrionidae families. São Paulo: All Print. 324 pp., 2006)LENCIONI, F.A.A 2006. Damselflies of Brazil, an illustrated indentification guide: II - Coenagrionidae families. São Paulo: All Print. 419 pp. and Garrison (2006)GARRISON, R.W., ELLENRIEDER, N.V. & LOUTON, J.A. 2006. Dragonfly genera of the New World An illustrated and annotated key to the Anisoptera. Baltimore: The Jonhs Hopkins University Press. 368 pp., as well as for described females and larvae, being complemented, when necessary, with data from the “Brazilian Taxonomic Catalog of Fauna” and articles describing the species, that contains their collection points as well as geographic coordinates data.

The habitat integrity of the sampled streams ranged from 0.194 to 0.970, suggesting a high environmental heterogeneity along with the sampled points. From the scores generated by the HII, ten points were classified as preserved, 15 had intermediate integrity and another ten were categorized as degraded (TABLE 1). The municipality of Sena Madureira was the one with the highest preservation index and the greatest collection effort due to its vast territorial extension (23,759,518 ha), which corresponds to 14% of the state of Acre. On the other hand, Brasiléia, with only 2% of the territory of Acre (3,928,174 ha), presents high degradation rates. In this location, five points were sampled, two of them being classified as intermediate and three as degraded (Table 1).

1. Taxonomic Notes

The specimens examined correspond to the morphological characteristics mentioned by the authors, which are: truncated paraprocts, cercus in lateral and laterodorsal views are truncated, with a wider base that tapers towards its distal apex, ending in a blunt tip (Figure 6). In addition, the characteristic yellow band can be seen below the ventral margin of the antehumeral band (Figure 7). According to von Ellenrieder & Garisson (2008)ELLENRIEDER, N.V. & GARRISON, R.W. 2008. Drepanoneura gen. nov. for Epipleoneura letitia and Protoneura peruviensis, with descriptions of eight new Protoneuridae from South America (Odonata: Protoneuridae), Zootaxa,1842, 1-34., specimens of D. loutoni are associated with lotic environments, being generally found perched in riparian vegetation or performing active flights close to the water surface, making the individuals difficult to be captured. In our collections, these characteristics were evidenced. Our sampling localities for D. loutoni correspond to first-order streams with a well-established band of riparian vegetation, light entering at various points along the bed, with HII score of 0.497. When there was no direct sunlight, individuals were observed perched on the tips of branches and leaves at a maximum height of 1.5 m. Under strong light conditions, specimens were observed flying close to the water surface on the stream bank.

Discussion

In total, 140 species were recorded for the Acre state, becoming the fifth second the greatest diversity of Odonata in the Northern region, only behind Amazonas (n = 364), Pará (n = 310), Mato Grosso (n = 285) and Rondonia (n = 206) (García-Júnior et al. 2022GARCIA JUNIOR, M.D.N., DAMASCENO, M.T.S., VILELA, D.S. & SOUTO, R.N.P. 2022. The Brazilian Legal Amazon Odonatofauna: a perspective of diversity and knowledge gaps. Ento. Brasilis. 15: e977.). Following, we have the states of Amapá with 119 (Garcia Junior et al. 2022GARCIA JUNIOR, M.D.N., DAMASCENO, M.T.S., VILELA, D.S. & SOUTO, R.N.P. 2022. The Brazilian Legal Amazon Odonatofauna: a perspective of diversity and knowledge gaps. Ento. Brasilis. 15: e977.) and Roraima with 82 species (Garcia-Junior et al. 2022GARCIA JUNIOR, M.D.N., DAMASCENO, M.T.S., VILELA, D.S. & SOUTO, R.N.P. 2022. The Brazilian Legal Amazon Odonatofauna: a perspective of diversity and knowledge gaps. Ento. Brasilis. 15: e977.). However, considering that the information gathered in our study represents only a portion of the Acre state, we cannot rule out the possibility that this number could be even higher. Therefore, the need to carry out complementary samplings in other places in Acre is evident, as well as in more marginal points on the border with Amazonas and Perú. This is more evident in the center and northern portions of the state, where there are only a few records from the literature for the municipalities of Marechal Thaumaturgo (code number 39), Taraucá (code number 40) and Mâncio Lima (code number 42).

Our sampling effort was efficient but still shows a large gap for the Odonata knowledge in Acre. All information and occurrence records presented in this study come from nine municipalities in Acre, which correspond to approximately 22% of the total extension of the state, where the environmental protection units are the most representative in the study. As reported by Koroiva et al. (2020b)KOROIVA, R., NEISS, U.G., FLECK, G. & HAMADA, N. 2020b. Checklist of dragonflies and damselflies (Insecta: Odonata) of the Amazonas state, Brazil. Biota Neotrop, 20 (1). https://doi.org/10.1590/1676-0611-BN-2019-0877 (last access in 16/12/2021)
https://doi.org/10.1590/1676-0611-BN-201... , little information is found in the literature and in the databases, being Acre one of the most poorly explored states of Brazil. In this context, this study is the first compendium on the Odonatofauna for the state. Thus, this checklist represented a great effort and the first step towards trying to synthesize the state of knowledge of dragonflies for this region.

Recently, Garcia-Junior et al. (2022)GARCIA JUNIOR, M.D.N., DAMASCENO, M.T.S., VILELA, D.S. & SOUTO, R.N.P. 2022. The Brazilian Legal Amazon Odonatofauna: a perspective of diversity and knowledge gaps. Ento. Brasilis. 15: e977. reported the total number of species (n=82) for the state of Acre. However, they recorded from bibliographic research and did not inform the coordinates of the locations where the species were recorded, which significantly limits the use of this information. In our study, we increase the total number of Odonata species for the Acre state, based on information from field and literature, increasing the number to 140 species. In addition, we provide additional information on the localities where each species was collected and information related to the category of threat and knowledge about females and larvae. This type of information is essential as it allows more accurate assessments of the threats that species face, ensuring better strategies for their conservation (IUCN 2022). Our sampling effort was efficient but still shows a large gap for the Odonata knowledge in Acre.

As a result, the species Drepanoneura loutoni is reported for the first time in Brazil, being collected in the municipalities of Sena Madureira and Assis Brasil in eight streams. The occurrence of this species was expected because it is a species that has a distribution in the department of Madre de Dios, in Peru, which borders Brazil (Ellenrieder & Garrison 2008ELLENRIEDER, N.V. & GARRISON, R.W. 2008. Drepanoneura gen. nov. for Epipleoneura letitia and Protoneura peruviensis, with descriptions of eight new Protoneuridae from South America (Odonata: Protoneuridae), Zootaxa,1842, 1-34.). This species has a strong connection with first and second order streams, in environments with dense vegetation cover. The genus Drepanoneura is known to occur along rivers and streams within forests, occupying large allopatric distributions from southern Panama through the foothills of the Andes Mountain range in Colombia, Ecuador, and Peru (Ellenrieder & Garrison 2008ELLENRIEDER, N.V. & GARRISON, R.W. 2008. Drepanoneura gen. nov. for Epipleoneura letitia and Protoneura peruviensis, with descriptions of eight new Protoneuridae from South America (Odonata: Protoneuridae), Zootaxa,1842, 1-34.), and we found D. loutoni in a similar environment in Acre state. However, except for this basic occurrence information, D. loutoni has still large gap in its knowledge, as the larval stages are still undescribed, and little is known about its autoecological aspects.

Our results also show that many species still do not have descriptions of larvae and/or females, which hampers the advance of the taxonomic knowledge of the group. Therefore, in addition to taxonomic improvement, information regarding basic biology is of great importance. For instance, the distribution or status of populations is essential for us to advance and further integrate studies with Odonata, and effectively contribute to the assessment of endangered species such as the List of Threatened Species of ICMBio (2018), and IUCN (https://www.iucnredlist.org).

Our results show a high environmental heterogeneity (HII 0.194 - 0.970) within the sampled points, most of which are located within conservation units. However, Acre is within the deforestation arc, where a wide range of anthropogenic activities that generate changes in land use exists (Aguiar et al. 2016AGUIAR, S., SANTOS, I.S., ARÊDES, N. & SILVA, S. 2016. Redes-Bioma: Informação e comunicação para ação sociopolítica em eco regiões. Ambient. soc., 19(3), 233-252.). Furthermore, in the Amazonian context, there are considerable evidence showing how odonates are affected by the loss of environmental integrity caused by land use modifications (Calvão et al., 2016CALVÃO, LB, NOGUEIRA DS, DE ASSIS MONTAG L.F., LOPES M.A. & JUEN, L. 2016. Are Odonata communities impacted by conventional or reduced impact logging? For. Ecol. Manage. 382: 143-150., Oliveira-Junior & Juen 2019OLIVEIRA-JUNIOR, J.M.B. & JUEN, L. 2019. The Zygoptera/Anisoptera ratio (Insecta:Odonata): A new tool for habitat alterations assessment in Amazonian streams. Neotrop. entomol. 48 (4), 552-560., Brasil et al. 2020). Thus, these results can indicate that Odonata communities are suffering strong pressures in the region. Therefore, we consider it necessary to expand the sampling efforts within a gradient of ecological conditions (from heavily impacted to pristine environments) likewise, the implementation of biomonitoring programs.

The information derived from our samplings will be of great importance in assessing the status of Odonata diversity in the Acre state, helping to identify threats and conservation strategies to be developed in the future. This study was carried out almost predominantly in the eastern zone of Acre, where the heaviest anthropogenic pressure in that state is located. The western region of the state still contain large areas of vegetation cover with many different phytophysiognomies such as campinaranas, indigenous lands (geographically more rugged), and with three types of water (clear, white and black). This entire arrangement of geophysical characteristics has a high potential for endemism and establishment of species with greater environmental demand.

Finally, this study highlights the importance of sampling efforts in poorly explored regions such as Acre state, making a significant contribution to the knowledge of the Neotropical odonatofauna and to one of the most biodiverse regions such as the Amazon biome.

Acknowledgments

We are grateful to the Federal University of Acre (UFAC) and Ichthyology Lab (Ictiolab) for logistical support in the surveys; to Federal University of Pará (UFPA) Ecology and Conservation Lab (LABECO) for collaboration in identifying the specimens and data analyses. This work was supported by the National Council for Scientific and Technological Development (CNPq) (process: 428961/2018-5) through the project “Diminishing Linnean and Wallacean gaps in aquatic biota in the Amazon”; by National Program for Academic Cooperation in the Amazon - PROCAD Amazon (process: 88887.200518/2018-00), through the project “Effect of land use and land cover on biodiversity and ecosystem functions in the South-Western Amazon”; and by Coordination for the Improvement of Higher Education Personnel (CAPES; 88881.145918/2017-01) through project “Climate Adaptation and Conservation of Brazilian Biodiversity Based on Regional Climate Models”. We thank Laura Santacruz for her help in the preparation of the map. Finally, we are grateful to the Federal Institute of Acre (IFAC) for their support in field activities and the scholarship to the main author, through CAPES. L.J. are grateful to CNPq for his productivity grant to (304710/2019-9). C.M.P. are grateful to the CNPq for granting a doctoral scholarship (process: 141113/2020-0). This manuscript is the result of the scientific initiation of the first author, J. C. M. F., who received a grant from CNPq (process: 136770/2021-5). L.B.C. thanks CNPq for granting her a scholarship (process 154761/2018-4), and CAPES: PROCAD-AM (88887.512256/2020-00 and 88887.600197/2021-00). TB thanks to the Mato Grosso Federal Institute of Scientific and Technological Education (IFMT) for granting a license to conduct this research.

Supplementary Material

The following online material is available for this article:

Table S1 - Richness estimate performed for each of the sampled points

References

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