The Odonata of Argentina: state of knowledge and updated checklist

An updated checklist of the 282 species of Odonata known to occur in Argentina is presented along with distributional information by province and ecoregion. Ten new records for the country and 87 new provincial records are provided. At present, 17 species of Odonata are considered endemic to Argentina, and distribution maps for each of them are provided. Information on larvae and conservation status according to the IUCN Red List of Threatened species is also provided; there are still 98 larvae unknown and 169 species unassessed.

Argentina is a vast country (mainland area of 2,780,400 km 2 ) located in southern South America. It is subdivided into 23 provinces and one autonomous city, Buenos Aires, which is the federal capital of the nation ( Figure 1A). Climatic conditions range from subtropical with hot weather in the north to subantarctic in the far south. Consequently, there is a wide variety of ecoregions within the country; according to Brown and Pacheco (2006), there are 18 ecoregions including the marine platform ( Figure 1B). Its latitudinal extent, topography and complex geological history provide a wide variety of ecological conditions that determine a complex biota. There are two main faunistic components, a neotropical one in the north and center of the country between 34°and 36°S, where the southernmost limit of many widespread American genera is found (e.g. Acanthagrion, Argia, Hetaerina, Erythemis, Miathyria, Micrathyria, Perithemis, Tauriphila, and Tramea), and a subantarctic one in the south that includes many remarkable Patagonian endemics (e.g. family Neopetaliidae) (Muzón, Pessacq, & Lozano, 2014).
In this contribution we provide a revision of the state of knowledge of the order Odonata in Argentina and include an updated checklist of the species recorded up to December 2018.   (Navás, 1933): [NA]; BUE, CHA (Ris, 1913;von Ellenrieder, 2010;von Ellenrieder & Garrison, 2003), COR, JUJ, MIS (CYM; DIP; PAM; SEL) -L {According to Garrison, von Ellenrieder, and Louton (2006) the larva was described by Carvalho (1988) as T. ditzleri}. The record from Jujuy belongs to Fraser (1947); the single specimen was determined as Gynacantha trifida and no locality was mentioned.  Garrison et al. (2006) the larva was described by Belle (1964)  Archaeogomphus infans (Ris, 1913): [NA]; MIS (Ris, 1913) (CYM) -L {Not described}. This species was originally described by Ris (1913) based on specimens from MIS (without exact locality) and Espirito Santo (Brazil). This species was never reported again from Argentina, and it was not included in the last checklist (von Ellenrieder & Garrison, 2008a). In this contribution this species was recorded for MIS (3). Phyllocycla foliata Belle, 1988: [NA]; MIS (Belle, 1988) (SEL) -L {Not described}. This species was described by Belle from specimens collected by Jurzitza in Misiones (Parque Nacional Iguazú). However, it was not listed by von Ellenrieder and . Phyllocycla propinqua Belle, 1972: [NA]; ENT (Belle, 1988), MIS (CYM; PAM; SEL) -L {Needham, 1940}. This species was recorded by Belle (1988) from Entre Ríos. However, it was recorded only for Misiones by von Ellenrieder and . Phyllocycla vesta Belle, 1972: [NA]; BUE (PAM) -L {Not described}. Phyllocycla viridipleuris (Calvert, 1909) Navás (1927b) mentions this species for CBA (Sierra de Cordoba) based on one female. This is likely to be a misidentification of D. mincki. Diastatops intensa Montgomery, 1940: [NA]; CHA (2), CBA, COR, ENT, FOR (Montgomery, 1940;Ris, 1928;von Ellenrieder, 2010) 1991}. Navás (1922) mentioned this species for BUE; since this is likely to be a misidentification the record from BUE has been removed. von Ellenrieder and  removed this species from the checklist of Argentina based on the supposition of an allopatric distribution with A. aepiolum. However, Lozano (2013) found that some specimens from COR province were actually this species. Therefore, previous records of A. ascendens from MIS (Jurzitza, 1981) which were removed from the checklist by von Ellenrieder and  were included with doubts here since its presence in COR makes its presence in MIS likely. Acanthagrion cuyabae Calvert, 1909 Navás, 1920: [DD]; BUE -L {Not described}. According to Pessacq (2008) the identity of this species is doubtful, because its type material is lost and its original description is poor. This species could be a synonym of one of the other species of Peristicta. In the original description there is no reference to the exact locality, Muzón et al. (2015) believe that this species was collected in DIP or near DIP because most localities from Buenos Aires province, cited in Navás papers, correspond to DIP or towns close to the Paraná Delta front.

Changes made since the checklist of von Ellenrieder and Muzón (2008)
Since von Ellenrieder and , one family (Synthemistidae) and 27 species have been added: two Aeshnidae, two Austropetaliidae, eight Coenagrionidae, three Gomphidae, one Lestidae, and 11 Libellulidae. From these, 10 are new records provided in this contribution (see comments below on each of these species), 15 species were recorded after the checklist of 2008, and two species were recorded before 2008 but omitted in that checklist (Table 1). In addition, eight species have changed their taxonomic status since the last checklist ( Table 2). The family Synthemistidae is recorded for the first time in Argentina, due to the placement of Gomphomacromia within it in recent molecular studies (Carle et al., 2015). Among the newly recorded species, Acerathobasis nathaliae was previously known from the Atlantic Forest of Brazil (von Ellenrieder & Garrison, 2008b). This species is not common; in fact, A. nathaliae was previously known only from its type locality: São Pablo, Jacarei, Fazenda  Garrison (2009) Santana do Rio Abaixo (Lencioni, 2004). Argia tamoyo is not a common species either, but it had a wider distribution range; it was previously known from Brazil and Bolivia (Lencioni, 2017). Progomphus costalis has a wide distribution, where it has been recorded from Rio de Janeiro, Brazil, south to Uruguay (von Ellenrieder, 2009;von Ellenrieder, Molineri, & Emmerich, 2009).
The libellulids Dasythemis esmeralda, Erythrodiplax amazonica, E. unimaculata, and Micrathyria iheringi are widely distributed in South America. The records herein provided expand the southernmost limit of their distribution range. Micrathyria stawiarskii has a more restricted range, previously known from Goias to Rio Grande do Sul states in Brazil.
Phyllocycla foliata was described by Belle (1988) from specimens collected by Jurzitza in Misiones (Parque Nacional Iguazú). However, this species was not listed by von Ellenrieder & . Belle considered it to be very similar to P. argentina, which is sympatric with P. foliata. Therefore, it is important to revise the taxonomic status of this species.
Two species were removed from the checklist by von Ellenrieder and : Aeolagrion inca and Micrathyria debilis. The former one was recorded for FOR based on a specimen collected in Estancia Guaycolec. This specimen belongs to A. phillipi. However, the identification was done prior to the description of A. phillipi (Tennessen, 2009). Micrathyria debilis is a common species in Central America. von Ellenrieder and  mentioned this species for Entre Rios and Santa Fe based on records provided by Fraser (1947). However, it has not been found again in these provinces and is likely to be a misidentification.

Endemic species of Argentina
There are 17 species endemic to Argentina (Table 3; Figure 3). Even though Patagonia has remarkable endemics at the regional level (e.g. Neopetalidae), there are no Patagonian endemics exclusive of Argentina, all having been also recorded in Chile (Muzón, Pessacq et al., 2014).
Allopodagrion erinys, Peristicta lizeria, Phyllocycla foliata and Progomphus australis are only known from their original description; little is known on their biology and habitat preferences.
Castoraeschna decurvata inhabits lotic environments with small waterfalls and sand bottoms. Adults are fast flyers and were seen patrolling at 1.5 m above the river. Final-stage larvae were collected in vegetated areas near the shores (Rodrigues Capitulo & Jurzitza, 1989). There are two disjunct areas where it has been recorded: one in Córdoba province and the other one in Entre Rios province; both are within the ESP ecoregion. Further research is needed in order to Rhionaeschna haarupi occurs in marshy areas of Andean streams and rivers of the Precordillera (mountain ranges lying before the Andes) where it has been found at elevations between 900 and 2015m. This species is very rarely seen in the field.
Rhionaeschna pallipes has a unique distribution among the species traditionally included within the former subgenus Marmaraeschna, as it is not restricted to the Andes ; it has also been recorded in hilly areas of Córdoba and Buenos Aires. There are two old records in Santa Fe province in the Paraná river basin, but as there are no mountains there,  believe these records are questionable. This species inhabits rapidly moving waters. Larvae were found under stones and clinging to submerged roots of marginal vegetation in creeks (von Ellenrieder & Muzón, 2003a).
Members of the genus Staurophlebia are among the largest species of Argentine dragonflies (total length 80-95 mm). Staurophlebia bosqi is a rare species that has been recorded in a small area of the lower delta of the Paraná river. It inhabits streams within thick marginal forests of flood plains. It is very similar to Staurophlebia reticulata, the other congener recorded in Argentina; a taxonomic revision of these two is necessary in order to test their specific status.
The genus Andinagrion is almost exclusively distributed in Argentina; except for A. saliceti which has been also recorded in Uruguay, the other two known species of the genus, A. garrisoni and A. peterseni, are endemic to the country. Andinagrion garrisoni is known to occur in the Yungas (von Ellenrieder, 2009), whereas A. peterseni is more widely distributed within Argentina, found from Yungas south to Patagonia and east to Buenos Aires. These species inhabit lentic environments at stream edges in hilly areas with abundant aquatic vegetation.
Argia jujuya is also endemic to the Argentine Yungas; among the four species of Argia reported in the region (NW Argentina), A. jujuya occupies the smallest range and is not as frequent and abundant as other species . It inhabits lotic environments strongly vegetated with rooted aquatic and semiaquatic plants .
There are two endemic gomphids recorded from Buenos Aires: Phyllocycla vesta and Phyllogomphoides joaquini. Both species are rarely seen in the field or in collections. Adults are very good flyers that inhabit lotic environments. Only the larva of Phyllogomphoides joaquini has been described, and as other gomphids it was found burrowed in sandy bottoms. Progomphus auropictus occurs in the Paranaense Forest in Misiones (von Ellenrieder & Muzón, 2008). Adults were seen flying in gallery forest streams with rocky substrate. Little is known on the biology of this species; the larva is unknown.
Gomphomacromia nodisticta is a rare species endemic to the ecotone between the Monte de Sierras y Bolsones and Yungas ecoregions of the Brown and Pacheco (2006) scheme. It has been recorded at elevations between 2400 and 2700 m. This species inhabits mountain streams; the larva is still unknown.
Oligoclada haywardi was described by Fraser (1947) from Misiones. It was not found again until 2009, when it was discovered in Corrientes; in 2011 and 2012 it was rediscovered in Misiones. Adults were collected while flying in gallery forest streams and in lentic environments near these streams. The larva is unknown. It is likely that this species is also present in Brazil.
Finally, Oligoclada rubribasalis can be found at shallow marshes surrounding ponds and rivers, perching on leaves exposed to the sun in northeastern Argentina. Reproductive behavior was not observed, and the larva is still unknown (von Ellenrieder & Garrison, 2008a).

Provincial records
Since the publication of the checklist in 2008, a total of 237 provincial records have been added ( Figure 4); of these, 150 were either published after the publication of the checklist of von Ellenrieder and  or were published before and omitted in it (Table 4), and 87 are new provincial records added in this contribution.
Formosa, Salta, Tucumán and La Pampa are the provinces with more new records published since 2008; most of the records can be found in papers dealing with regional diversity (del Palacio et al., 2017;Rodríguez et al., 2018;von Ellenrieder, 2010;von Ellenrieder & Garrison, 2007). Most of the new records added here are for Misiones and Corrientes (17 and 16 respectively); these are highly diverse provinces and have been intensively surveyed during the last decade. Santa Fe and San Luis follow with 10 new records each; in this case these provinces had been poorly studied and with few field samples in the area many novelties were found.  There are 80 provincial records belonging to 62 species that could not be georeferenced ( Figure 5). The reason for this is that either the localities mentioned in the publication were not found or only provincial records were provided.
Seven species cited for Argentina are known only by provincial records: Telebasis carminita for Santa Fe, Archaeogomphus densus, Erythrodiplax anomala, Erythrodiplax famula, Erythrodiplax lativittata, and Allopodagrion erinys for Misiones and Macrothemis tessellata for Buenos Aires and Misiones. Further research is needed in order to confirm the presence of these species within the provinces in which they were recorded.

Provincial records removed
Aphylla dentata: Removed from BUE, ENT and SFE.
von Ellenrieder and  list this species for Buenos Aires, Entre Ríos, and Santa Fe. The records from Buenos Aires and Santa Fe belong to Ris (1904) and Navás (1927aNavás ( , 1928Navás ( , 1930; the record from Entre Ríos could not be found, but there is a mention of Aphylla dentata from Delta del Paraná (Rodrigues Capitulo, Mola, & Agopian, 1991). Belle (1992) stated that all specimens cited by Navás as A. dentata probably belong to Aphylla distinguenda. Therefore, taking into account that A. dentata has not been found again in these provinces we remove it from Buenos Aires, Entre Ríos and Santa Fe and transfer these records to A. distinguenda.
Erythrodiplax anomala: Removed from BUE. This species is distributed in eastern Brazil south to northeastern Argentina (Misiones). Navás (1922) mentioned this species for BUE. Santos (1953) says that its general appearance is similar to E. media and E. paraguayensis. Therefore, this species is likely to be a misidentification. Erythrodiplax juliana: Removed from ENT This species has been removed from ENT since the specimens belong to E. chromoptera.

Knowledge of larvae
The knowledge of the larvae of the Odonata recorded in Argentina is still far from complete. Of the 282 species recorded, the larva of only 184 (65%) have been described ( Figure 6). The situation at the generic level is much better, as of the 85 genera recorded, 70 (82%) have at least one Argentinean species with its larva described, and of the 15 remaining genera the larva of seven of them is known based on species not recorded in Argentina.

Ecoregional knowledge
At the ecoregional level, the Selva Paranaense and Yungas are the richest (Figures 7, 8A). This is not surprising, taking into account that many of the neotropical species have their southernmost distribution limits within these ecoregions. When plotting the richness of the ecoregions ( Figure 8A, B), it becomes evident that the knowledge of CHH is still far from complete; fewer species are recorded than in neighboring ecoregions ( Figure 8B). Little is known about the odonates of the Puna, where only three species have been recorded, and it is likely that this number is higher. These regions need to be better surveyed in order to improve their state of knowledge.

Conservation status
The Odonata is the first insect order to be assessed on a representative global scale for the IUCN Red List of Threatened Species (Clausnitzer et al., 2009). From the 282 species recorded in Argentina, only 113 species (40.07%) have been assessed globally using the IUCN categories and criteria (Figure 9). However, most of these assessments (73.45%) were done before 2010 and need to be updated ( Figure 10).
Efforts are being made to complete the global assessment of all neotropical species and publish them in the Red List. Therefore, it is estimated that all the Latin American species are going to Chalcopteryx rutilans Santos and Costa (1987) be assessed by 2021. At present, progress is being made in completing the National Red List of Odonata, the first national red list of an insect order within Argentina.  Muzón & Lozano (in press): This species has been described based on specimens collected in COR (CYM) and Brazil. Specimens from Argentina were collected in a marshy area around a pine plantation was crossed by a small creek.

Species yet to be described or in manuscript
Angelagrion sp.: Specimens from this genus were collected in ENT (DIP) and are under study.

Argentina in a South American context
The knowledge of the Odonata from South America has grown steadily in recent years, with many South American entomologists working on ecology, diversity, taxonomy, and conservation of dragonflies and damselflies. However, there are still gaps that need to be addressed: there are   many countries that do not have updated checklists (Table 6), and the specific richness is probably underestimated (for example in Bolivia and Paraguay); this can be evidenced in the fact that many new species are being described every year. Besides, little is known on the ecology, habitat preferences, and larvae of many species. When comparing the specific richness between South American countries, Argentina, with 282 known species, is behind Brazil, Venezuela, Peru, Ecuador, and Colombia (Table 6). This is not surprising taking into account that most of these countries are known for their high specific richness. However, when weighting the species richness with the country area, the situation is very different, with Argentina being one of the countries with the lowest values of species richness ( Table 6). The number of endemic species varies greatly among the South American countries. Brazil, with more than 300 species, is the country with the greatest number of endemic species. It is followed by Venezuela, Peru, Ecuador, and Colombia, as with the number of known species. However, when the percentage of endemic species is considered, Chile with 28.6% of endemic species is second to Brazil (Table 6).