A preliminary overview of the Brazilian Apioninae (Coleoptera: Brentidae) with an illustrated key for genera, and a checklist with distribution information

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More than 2,200 species of Apioninae have been described (Alonso-Zarazaga & Wanat, 2014), where they are found from high altitudes to sea level throughout the region (Alonso-Zarazaga 2004;Anderson & Kissinger 2002;Oberprieler et al. 2007;Alonso-Zarazaga & Wanat 2014) and where the species comprise about 205 genera and subgenera (Alonso-Zarazaga & Wanat 2014), seven supertribes and nine tribes (Bouchard et al. 2011;Alonso-Zarazaga 1990).Kissinger (1968) pioneered the study of the genera and subgenera of Apion while focusing on the fauna of North and Central America, where he described an extraordinary diversity of forms and demonstrated that the tegmen of male genitalia provides important characters to determine their taxonomy.In South America, the Apioninae comprise 190 species (Wibmer & O'Brien 1986) in 19 genera, 10 of which were thought to be endemic (Kissinger 1968(Kissinger , 2002(Kissinger , 2003(Kissinger , 2005a, b), b).Among other South American countries, Brazil also has no recent studies of the Apioninae and the little taxonomic information available can be found in 17 published studies that include 86 species (summarized and listed under the genus Apion Herbst, 1797 in the catalog of Wibmer and O'Brien 1986).
Currently, the only classification for suprageneric and generic Apioninae taxa is based on Palearctic fauna (Alonso-Zarazaga 1990, Ptaszynska et al. 2012, Winter et al. 2017).The Alonso-Zarazaga classification scheme does not include many North and Central American and most South American taxa, nor do the molecular studies of Ptaszynska et al. (2012) and Winter et al. (2017) include North, Central and South American taxa.Consequently, the basis for identification of the Apioninae of South America continues to be Kissinger (1968), even though obsolete.The genus Apion is now considered to be a monophyletic genus of 16 species that is restricted to the Palearctic (Alonso-Zarazaga 1990) and so many species listed by Kissinger (1968) remain in incorrect genera.
Today, hundreds of specimens have accumulated in collections in South American institutions under the genus Apion.This material is very important for taxonomic and systematic understanding of the Apioninae.Thus, we present a first step in understanding the Apioninae of Brazil by providing a checklist of genera and species, with their geographic distributions, host plants, citations of the relevant literature, and a key for the genera including photographs and illustrations.
We examined the type material of the following 13 species: Apion cydoniae Bondar, 1950 andA. zikani Heller, 1922 (Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil -MNRJ); Apion argentinum Béguin-Billecocq 1909, A. contrarium Photographic images were taken using a Leica MZ16 stereomicroscope, Leica DFC 500 camera, Leica 3D viewer module and version montage 4.7 (software).Drawings and images were edited in Photoshop CS6.Schematics of the male genitalia were drawn using a stereomicroscope or a microscope with a light camera coupled system or image capture system.

Results
From ca 230 specimens in collections in Brazil, we identified 10 genera and two subgenera of Apioninae in a total of 43 species.We identify 25 Brazilian species, 15 of which are placed in "Apion" in the broadest sense.Thirty new records are included, one for Brazil: Chrysapion Kissinger, 1968.Another 24 records are new for Brazil: the geographic distribution of Neapion Alonso-Zarazaga, 1990, subgenus Neotropion Alonso-Zarazaga, 1990 is extended to include Amazon (Acre and Pará) and Atlantic (São Paulo and Paraná) forests; Coelocephalapion Wagner, 1914 is extended to the Pantanal (Mato Grosso and Mato Grosso do Sul); Apionion Kissinger, 1998 now includes the Pantanal (Mato Grosso) and Atlantic Forest (Rio de Janeiro); Bothryopteron Wagner, 1912 is extended to the Amazon (Maranhão), Pantanal (Mato Grosso), Cerrado (Tocantins and Goiás) and Atlantic Forest (Santa Catarina); Coelopterapion Wagner, 1912 to the Pantanal (Mato Grosso), Cerrado and Atlantic Forest (Minas Gerais, São Paulo and Paraná); Mythapion Kissinger, 2005 now includes the Amazon (Amazonas); Stenapion Wagner, 1912 is also extended to include Amazon Forest (Pará), the Pantanal (Mato Grosso and Mato Grosso do Sul), Cerrado and Atlantic Forest (Minas Gerais and Santa Catarina).Apionion samson is reported for the first time from Brazil (Minas Gerais), two species of Coelopterapion, C. cionoides (Wagner 1912a) and C. testaceum (Wagner 1912a)

Discussion
We recognize 10 genera of Brazilian Apioninae, one of which is a first record for Brazil (Chrysapion) and which appears to be restricted to northeastern Brazil.Three genera are widely distributed in the New World: Alocentron, Coelocephalapion and Trichapion.The latter two genera are found throughout Brazil.Five genera (Apionion, Bothryopteron, Coelopterapion, Neapion and Stenapion) have more restricted distributions in South America (Alonso-Zarazaga and Lyal 1999) but also are found throughout Brazil.Coelopterapion is the only genus with most species subendemic to Brazil (Kissinger 1968) and whose distributions are restricted to the Cerrrado and Atlantic Forest.The recently described Mythapion is monospecific and found in Argentina, Brazil and Uruguay (Wibmer and O'Brien 1986;Kissinger 2005a), from the Amazon to the Pampas of South America.
Only 86 species of Apioninae from Brazil were described from 1833 to 1959, mostly by Hans Wagner, with the recent addition of two new species (De Sousa and Ribeiro-Costa 2018).Yet, Alonso-Zarazaga (pers. comm. 2017) reported that Don Whitehead estimated that the number of Brazilian Apioninae species is closer to 1,500, most of which are endemic.Alonso-Zarazaga and Wanat (2014) suggested 800 species for the Neotropical region, which is likely to be a large underestimation.More than 50 years have passed since the last Brazilian species were described.Thus, our descriptions and keys provide a new landmark for the taxonomy of the Apioninae in South America.Brazil is among the most biodiverse countries with many hotspots (Aleixo et al. 2010;Marques and Lamas 2006;Myers et al. 2000) and so the Apioninae is a very promising group and much more promising comparing parazitoid hymenopterans wasp or dipterans in South America.
We identified ca 230 especimens to genus or species.Taxonomic impediments, such as brief, incomplete, original descriptions, often without illustrations that would facilitate species recognition, prevent identification at the species level for most.Additionally, many small specimens apparently comprise a large number of morphotypes, but each morphotype included only a few specimens without marked sexual dimorphism.Thus, many specimens remain to be identified.
Upon examination of the Apioninae in Brazilian collections we found a large quantity of unidentified material, many specimens of which are only labelled Apion sp., while others were mixed Apioninae.We found no specimen that was identified with any generic name other than Apion, and there were no subgenera.Hence the challenge of this study, in which we provide a list for the Brazilian taxa and place them in genera and subgenera.All identification was through comparison with relevant diagnostic characters of the original descriptions, with the addition of currently available types or images of type material or with material previously identified by specialists.
External morphology and genitalia of males, both of which are fundamental for identification of taxa in the Apioninae, are described in Alonso-Zarazaga (1989, 1990, 2004) and Alonso-Zarazaga & Wanat (2014).Also, efficient use of the key requires the separation of morphotypes and identification of the sex of each morphotype.Species identification based only on females is essentially impossible and so males are required.For that end, an adequate collection with many specimens that can be dissected to identify sex is required (Alonso-Zarazaga 2004).If dissection is not possible, secondary sexual dimorphism must be identified and which can be observed in the rostrum (shorter in males, Fig. 18, wider and generally more coarsely sculptured and pubescent than in females, Fig. 19; Anderson & Kissinger 2002).Some males have mucro in at least one pair of tibiae, or the first tarsomere of one of the legs is modified as plantar spines (Fig. 26).The apical margin of ventrite 5 is truncated with a part of the pygidium being visible externally, or the pygidium is formed by the 8th tergite (7th in females, Fig. 24).In females, the legs have no special characters and ventrite 5 (Fig. 25) has a rounded margin (Alonso-Zarazaga 1990).Rarely, ventrite 5 of females (in some species) may have a median glabrous area or a median sulcus (Alonso-Zarazaga and Wanat 2014), such as in Trichapion sp. (Fig. 25).
Hundreds of specimens in South American collections are still waiting to be studied, many of them likely to be new taxa.Thus, these specimens may be among the 10 genera comprising the key, or they may be unknown genera or even be among the non-monophyletic hyperdiverse genera (Trichapion and Coelocephalapion).Thus, they demonstrate the potential of the group for future systematic research at all taxonomic levels.Additionally, studies must be carried out to recover monophyly of the genera and tribes and to clarify relationships of incertae sedis, all based on morphology, molecular, biogeography and host plant associations.