Melolonthidae Leach, 1819

Costa-Silva, Vinícius da, Ferreira, André da Silva, Bordin, Bruna R., Basílio, Daniel S., Rodrigues, Diego F., Gama, Emanuel R. R., Fuhrmann, Juares, Mariano, Júlia, Bevilaqua, Marcus, Cherman, Mariana A., Duarte, Paulo R. M., Grossi, Paschoal C. & Vaz-de-Mello, Fernando Z., 2024, Brazilian Scarabaeoidea (Insecta: Coleoptera) in the Taxonomic Catalogue of the Brazilian Fauna, with a key for families and subfamilies, Zoologia (e 23075) 41, pp. 1-37 : 12-14

Melolonthidae Leach, 1819

Figs 5A–F, 6H, 6J–M

Diagnosis. Melolonthids are difficult to be distinguished from other scarabaeoids because the taxon is highly diversified, usually they have the following features combined: mandibles strongly sclerotized; labrum and mandibles partially exposed or hidden by the clypeus dorsally; antennal club formed by three to seven lamellar articles, club in general as long as the funicle, lamellae with fanlike movement; abdomen with six ventrites, propygidium strongly sclerotized, junction (sometimes fused) with the corresponding sternite next to the last pair of spiracles; pygidium completely exposed or partially covered by the elytra; male genitalia bilobed or fused; body size from 3 to 170 mm ( Endrödi 1966, Cherman and Morón 2014).

Remarks. Melolonthidae are probably (if not) the most specious family of Scarabaeoidea , comprising approximately 18,684 described species worldwide ( Schoolmeesters 2023). Of these species, 1,591 are known from Brazil ( Table 2), corresponding to about 8.5 % of the global diversity of the family and representing approximately 62.8% of the Brazilian fauna of Scarabaeoidea . Brazilian melolonthids are distributed in six subfamilies, where Melolonthinae , Rutelinae and Dynastinae have the most representatives, with 621, 476 and 396 species, respectively; the other three are Sericinae, Orphninae and Aclopinae , which encompass 75, 18 and 5 species, respectively ( Vaz-de-Mello and Grossi 2023).

Dynastinae comprise the group of beetles popularly called rhinoceros beetle ( Ratcliffe et al. 2020). In some Brazilian regions they are known as “cascudinho” or “besouro-de-chifre” ( Lenko and Papavero 1996). The subfamily is currently subdivided in eight accepted tribes (whose definitions are unstable), six of which are known from Neotropical region, all represented in Brazil: Agaocephalini , Cyclocephalini , Dynastini , Oryctini , Pentodontini and Phileurini ( Endrödi 1985) . The taxonomic knowledge on the Brazilian dynastines is largely fragmented in literature and the synopsis published by Endrödi (1985) remains the main work covering the taxonomy of most tribes, genera and species. An up to date on the taxonomy for most taxa of the Dynastinae from Brazil is needed, mainly for greatly specious genera such as Cyclocephala Dejean, 1821 and Heterogomphus Burmeister, 1847 . However, it’s worth highlighting the importance of recent taxonomic studies that produced new information regarding the Brazilian dynastines [see Sobral et al. (2018) for Aegopsis Burmeister, 1847 ; López-GarcÍa and Deloya (2019, 2022) for Tomarus Erichson, 1847 ; Sobral et al. (2019) for Colacus Ohaus, 1910 ; Duarte and Grossi (2020a), and Duarte et al. (2022) for Bothynus Hope, 1837 ; Duarte and Grossi (2020b) for Podischnus Burmeister, 1847 ; Prandi et al. (2020) for Megasoma Kirby, 1825 ; Costa et al. (2022) for Gibboryctes Endrödi, 1974 ]. Adults of Dynastinae from Neotropical region are recognized by the body usually without metallic aspect (except some members of Agaocephalini ); labrum not apparent, hidden below clypeus; outer margin of mandibles mostly exposed laterally to clypeus; antennae usually with10 antenomeres and club with three lamellae; meso- and metatarsi with both claws simple, equal, not movable, devoid of cleft, tooth or serrations; propygidium with or without stridulatory striae; sexual dimorphism usually pronounced: males of some taxa ornamented with remarkable horns that are absent or reduced in females. They are predominantly nocturnal or crepuscular when adults, being attracted to light at night ( Ratcliffe et al. 2020). Some representatives of Cyclocephala are the main floral visitor of Annonaceae and Araceae in Brazil ( Maia et al. 2012). The larval stages of Dynastinae usually feed on decaying plant matter, mainly wood ( Ritcher 1958, Ratcliffe et al. 2020), while others feed on roots of living plants and, in some situations, they can be considered of economic importance by damaging roots of cultivated plants ( Gassen 1989, Lourenção et al. 1999, Oliveira and Frizzas 2021, Oliveira et al. 2008, Cherman and Grossi 2020).

Melolonthinae are the richest subfamily in Brazil, where they are represented by 625 species in 30 genera and five tribes ( Cherman and Vaz-de-Mello 2024), but also among the Scarabaeoid subfamilies, with 6,009 species worldwide ( Schoolmeesters 2023). This number was even greater ( Evans 2002) before the splitting of the sericines and the sericoidines mainly ( Ahrens et al. 2011, 2014, ŠÍpek et al. 2016) into new subfamilies ( Dietz et al. 2023, Schoolmeesters 2023). Among the five Brazilian tribes: Macrodactylini , Diplotaxini , Melolonthini, Hopliini , and Tanyproctini, the first three are the most representative (530, 51, and 37 species, respectively) and are also called the “true melolonthines”, giving their close relationship with Melolonthini ( Coca-Abia 2007, Ahrens et al. 2014, Cherman et al. 2016, Costa et al. 2021). Adults of Brazilian melolonthines are characterised ( Evans 2002, Cherman and Pereira 2020) by having 5–25 mm in length, dorsal surface often conspicuously setose or scaled; color mostly reddish brown or black; mandibles and labrum well developed and completely hidden from above; antennal club oval to elongate, in general thin; head and pronotum always unarmed; metatibial spurs adjacent (when present), meso- and metatarsal claws in general toothed, cleft, or serrate; abdomen with five or six ventrites fused laterally, suture sometimes visible; and pygidium exposed. Sexual dimorphism weakly developed, most males with abdomen less convex, longer antennal club and tarsi than females. Often called May beetles, June beetles, and chafers, melolonthines are generally phytophagous, with some genera of considerable economic importance (i.e., Phyllophaga Harris, 1827 , Liogenys Guérin-Méneville, 1831 , and Plectris Le Peletier & Audinet-Serville, 1828 ) ( Cherman et al. 2011, 2014, Valmorbida et al. 2018, Cherman and Pereira 2020, Coutinho et al. 2022), giving the nocturnal defoliation activity of adults and rhizophagous habits of larvae ( Ritcher 1966, Morón 1997, Morón et al. 1997, Evans 2002). Identification keys to Brazilian species of Melolonthinae are sparse and fragmented, available for certain tribes ( Macrodactylini : Fuhrmann and Vaz-de-Mello 2017; Diplotaxini : Cherman et al. 2019) or genera, such as Plectris ( Frey 1967) , Liogenys ( Cherman et al. 2019) , and Phyllophaga ( Frey 1975) . Additional works including keys to species of Melolonthinae occurring in agricultural environments are Cherman et al. (2013) (species from southern Brazil), Cherman and Pereira (2020) (Brazilian species), and Brumley et al. (2020) (exotic species of Australia).

Rutelinae MacLeay, 1819 are the second largest subfamily of Melolonthidae , with about 4,200 described species in the World ( Jameson 1998, Hardy 1991, Jameson 2002c, Jameson and Hawkins 2005, Krajcik 2007, Jameson and Ratcliffe 2011, Morón and RamÍrez-Ponce 2012, Moore et al. 2017), and the highest species richness recorded for tropical regions ( Jameson 1998). Seven tribes are currently allocated to the Rutelinae : Adoretini , Alvarengini, Anatistini , Anomalini , Anoplognathini , Geniatini and Rutelini ( Bouchard et al. 2011) . Anomalini and Rutelini are recorded for the Nearctic, Neotropical, Palearctic and Afrotropical regions, while the Adoretini are recorded for the Palearctic and Afrotropical regions ( Ohaus 1918). As for the Alvarengiini , records in Brazil are restricted to Bahia and Paraná states ( Bento 2019). Anatistini is recorded in the Neotropical region; Anoplognathini is recorded for Australia and the Neotropical region; and Geniatini has records only in the Neotropical region ( Ohaus 1918). In the Neotropical region, about 1,352 species of Rutelinae are recorded ( Morón et al. 1997, Moron 2004, Villatoro and Jameson 2001, Villatoro 2002, Jameson and Hawkins 2005, Jameson 2008, Soula 2011, Filippini et al. 2016, Ferreira et al. 2017, Hawks 2017, Moore et al. 2017, Seidel et al. 2017, Sierra 2017, Ferreira et al. 2019, Ferreira and Grossi 2022, Ferreira et al. 2022), of which 476 species and 103 subspecies allocated in 58 genera are recorded for Brazil ( Ferreira and Grossi 2023). Adults of Brazilian rutelines are for the most part very shiny, metallic blue, green, brown or reddish gold, and can vary from intense and shiny black to metallic gold, with a series of contrasting and iridescent combinations ( Morón et al. 1997). Rutelinae are characterized by elongated and robust oval body, convex back, 3–30 mm in length; labrum weakly produced beyond apex of clypeus, except in Anomalacra Casey, 1915 ( Anomalini ); antennae with 8–10 antennomeres; scutellum exposed; transverse procoxa; mesotibia with two spurs at apex, adjacent; tarsal claws independently movable, unequal in length and often weakly divided at apex; and exposed pygidium ( Ohaus 1934, Machatschke 1965, Morón et al. 1997, Jameson 2002c). Adults are strictly phytophagous and some play an important ecological role in the pollination of some plant species; the larvae are saprophytic and contribute directly to the decomposition process of dead organic matter deposited inside the forests, as well as to nutrient cycling ( Hardy 1991, Morón et al. 1997, Paucar-Cabrera 2003). Some species feed on the roots of plants of economic importance (i.e., Leucothyreus MacLeay, 1819 and Paranomala Casey, 1915 ) ( Ritcher 1958, Jameson et al. 2003, Jameson and Howkins 2005). Despite the biological, ecological and diversity importance of rutelines, there are still gaps in the taxonomic knowledge of the group ( Morón et al. 1997). In some of the tribes, most of the genera do not have identification keys for the species (i.e., Geniatini ). However, important studies have been conducted on the group in recent years, especially in Brazil, including: (i) Systematic reviews in Alvarengiini ( Bento 2019) , in Geniatini to Eunanus Ohaus, 1909 ( Ferreira et al. 2024), Evanos Castelnau, 1840 ( Grossi and Vaz-de-Mello 2018), Lobogeniates Ohaus, 1917 (Ferreira unpublished data) and Rhizogeniates Ohaus, 1909 (Ferreira et al. unpublished data), and in Rutelini to Byrsopolis Burmeister, 1844 ( Medeiros et al. 2022) and Oplognathus MacLeay, 1819 ( Carvalho et al. 2021); (ii) Species descriptions with identification keys in Rutelini to Chlorota Burmeister, 1844 ( Medeiros and Grossi 2020), Homonyx Guérin-Méneville, 1839 (Ferreira et al. unpublished data), Macraspis MacLeay, 1819 ( Medeiros et al. 2019, Bento and Grossi 2021), Moronius Grossi & Vaz-de-Mello, 2015 ( Carvalho and Grossi 2018), Pelidnota MacLeay, 1819 ( Ferreira et al. 2017, 2018, 2021, 2022, Ferreira and Grossi 2022) and in Geniatini to Trizogeniates Ohaus, 1917 ( Ferreira et al. 2019); and (iii) proposition of phylogenetic hypotheses in Geniatini , Lobogeniates (Ferreira unpublished data), Rhizogeniates (Ferreira et al. unpublished data) and Geniates Kirby, 1818 (Bento et al. unpublished data).

Sericinae are being considered a subfamily since phylogenetics hypotheses show a series of tribes (i.e., Sericini, Sericoidini , and Athliini ( Ahrens 2006, Smith et al. 2006, Smith and Evans 2018)) clustered together, which were traditionally recovered within Melolonthinae ( Ahrens et al. 2011, 2014, Gunter et al. 2016, Dietz et al. 2023). This subfamily comprises 5,322 species ( Schoolmeesters 2023): the “true sericines”, 4,000 species worldwide ( Eberle et al. 2017), and the other 1,322 called the“Southern World” Melolonthinae , giving their distribution over the Southern Hemisphere ( Ahrens et al. 2014, Eberle et al. 2014). Some authors also consider the latter group as another subfamily, Sericoidinae ( Dietz et al. 2023, Schoolmeesters 2023). American Sericini have recently been assessed thoroughly ( Pacheco et al. 2020, 2021, 2022a, 2022b, 2022c, 2023, Pacheco and Ahrens 2023), as well as the sericoidines ( Costa et al. 2020, 2021). In Brazil, Sericinae are represented by 75 species in three tribes: Sericini, with 50 species; Sericoidini , with 23 species; and Athliini with two species. The species richness of this subfamily in the Neotropical region and especially in Brazil is still quite underestimated, and numerous species await description (FC Costa and TL Pacheco, personal communication). Available keys to American Sericinae are still scattered and out-of-date in most cases. For Brazilian Sericini, there are up-to-date identification keys to Symmela Erichson, 1835 ( Pacheco et al. 2022c) and to Raysymmela Saylor, 1947 species ( Pacheco et al. 2022b); Frey (1973) to Astaena Erichson, 1847 species. For the Brazilian Sericoidini, Frey (1973) is used for some Blepharotoma Blanchard, 1850 species, and there is a key to Ovomanonychus Costa, Cherman & Iannuzzi, 2020; while a key to Manonychus Moser, 1919 is being currently elaborated (FC Costa, personal communication). A key to Athliini is available in Smith and Evans (2018).

Aclopinae are a poorly known group of scarab beetles distributed in Australia and South America ( Neita-Moreno et al. 2019). Aclopus Erichson, 1835 is the only genus of the subfamily recorded in Brazil, where five species are known, all distributed in central and southern regions ( Ocampo and Mondaca 2012, Neita-Moreno et al. 2019). Apparently, there are no keys to identify species of Aclopus . Allsopp (1981, 1983), Ocampo and Mondaca (2012) and more recently Neita-Moreno et al. (2019) provided identification keys to genera and species of South American and Australian Aclopinae , but Aclopus was not included. Immature stages and natural history of the Aclopinae members are also unknown.

Orphninae are widely distributed throughout tropical and subtropical regions of the southern continents ( Frolov 2012). Four genera are known from Brazil: Aegidiellus Paulian, 1984 ; Aegidinus Arrow, 1904 ; Aegidium Westwood, 1845 ; and Paraegidium Vulcano, Pereira & MartÍnez, 1966 . All Brazilian Orphninae genera were studied in recent taxonomic revisions and contributions: see Colby (2009) and Frolov et al. (2019) for Aegidinus ; Frolov et al. (2017a) for Aegidium ; Frolov et al. (2017b) for Paraegidium , and Frolov et al. (2017c) for Aegidiellus . Regarding the immature stages of the Brazilian orphnines, only those of Paraegidium costalimai Volcano, Pereira and Martinez, 1966 are known ( Sousa and Fuhrmann 2020).