Scarabaeidae Latreille, 1802

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 : 16-17

Scarabaeidae Latreille, 1802

Figs 5H–I, 6F–G

Diagnosis. Antennae with 8 or 9 antenomeres, with lamellae mobile and compactable club formed by the last three antennomeres. Clypeus and gena dorsoventrally flattened and usually forming a broad anterior surface, being separated from each other by a dorsal suture (sometimes indistinct). Mandibles in Brazilian species with incisive area membranous. Labrum and mandibles not visible, base of mandibles sometimes visible laterally. Abdomen with six ventrites.

Remarks. Scarabaeidae are a cosmopolitan family with 36,009 described species ( Schoolmeesters 2023). In Brazil, it is represented with 826 species and 104 genera distributed into two subfamilies ( Table 2): Scarabaeinae ( Fig. 5I) and Aphodiinae ( Fig. 5H). This family is, in its majority, composed of coprophagous beetles which feed and nest directly on the faecal matter of mammals, giving them the popular name of dung beetles ( Halffter and Edmonds 1982).

The subfamilies can be determined by the following combination of characters: Scarabaeinae mesocoxae are usually separated by a distance greater than or equal to their width and the metatibiae generally presents only one apical spur; on the other hand, Aphodiinae mesocoxae are usually separated by a distance smaller than their width and the metatibiae generally presents two apical spurs. Scarabaeinae usually have the propygidium and pygidium exposed, while in Aphodiinae the propygidium is completely covered by the elytra and the pygidium is partially covered. Other differences can be found in the reproductive system: females of Scarabaeinae have only one ovary with one ovariole, while females of Aphodiinae have two ovaries each with six ovarioles.

Aphodiinae comprises more than 3,500 species of generally small (1.5–8.0 mm) and saprophagous beetles ( Stebnicka 2001 a, Schoolmeesters 2023). Their biology is extremely diverse with some groups being found associated with mammal dung, under wood-bark, or fungi, while some species have been reported feeding on the dung of beetles such as Passalidae and few genera can even be found associated with social insects ( Chapin 1940, Stebnicka 2001a, 2007a, 2007b).

In Brazil, Aphodiinae is represented by 145 species, 40 genera, and five tribes: Aphodiini , Eupariini , Odontolochini , Psammodiini , and Rhyparini ( Vaz-de-Mello 2023b). A key for New World genera of Aphodiinae has been written by Skelley (2008), and an identification guide with an updated key for genera in Brazil is under development by one of the authors (E. Gama unpublished data)

The knowledge on the Aphodiinae has improved considerably in recent years with many groups being reviewed. The Italians, Marco and Giovanni Dellacasa, have reviewed many groups in Aphodiini , thus, it is recommended to consult these authors when studying this tribe (see Dellacasa et al. 2001, 2011, 2012). Many groups of Eupariini have also been reviewed (see Stebnicka 2009), including Ataenius Harold, 1867 , the most specious genus in the New World with at least 190 described species ( Stebnicka 2007b). In Brazil, 55 species of Ataenius are recognized, representing approximately 37% of the Aphodiinae known in Brazil ( Vaz-de-Mello 2023b). Ten of the 11 species groups of Ataenius are present in Brazil and keys for these groups or for species within each species group can be found in Stebnicka’s works (2001b, 2003, 2004, 2005, 2006, 2007c, Stebnicka and Lago 2005). Psammodiini in Brazil have no recent taxonomic revisions; the last study was conducted by Gordon and Pittino (1992). For the identification of genera and species of Neotropical Odontolochini, Skelley (2007b) is recommended. For the Rhyparini , only two genera are present in Brazil: Aschnarhyparus Makhan, 2006 and Termitodius Wasmann, 1894 ; both genera have been briefly reviewed by Skelley (2007a) and Skelley et al. 2022).

Whereas, the subfamily Scarabaeinae is a highly diverse group, comprising approximately 6,840 species distributed worldwide ( Schoolmeesters 2023). They are primarily coprophagous, with some exhibiting secondary necrophagy or saprophagy ( Halffter and Edmonds 1982). These beetles typically have an oval-shaped body, with species ranging from 1.9 mm (e.g., Degallieridium lilliputanum Vaz-de-Mello, 2008) to more than 50 mm in length – e.g., Coprophanaeus ensifer (Germar in Wiedemann and Germar, 1821). The genera and subgenera of Neotropical Scarabaeinae can be identified using the multilingual dichotomous key available in Vaz-de-Mello et al. (2011).

In Brazil, there are 784 described species of Scarabaeinae in 68 genera ( Vaz-de-Mello 2023b). However, this number is subject to change as ongoing taxonomic research on scarab beetles progresses. Despite numerous taxonomic studies conducted in recent years on various groups, such as Sylvicanthon Halffter & MartÍnez, 1977 ( Cupello and Vaz-de-Mello 2018), Scybalocanthon MartÍnez, 1948 ( Silva and Valois 2019), Canthon (Pseudepilissus) MartÍnez, 1954 ( Vieira et al. 2020), Canthon (Peltecanthon) Pereira, 1953 ( Nunes et al. 2020a); Canthon (Goniocanthon) Pereira & MartÍnez, 1956 ( Nunes et al. 2019); Dichotomius (Homocanthonides) Luederwaldt, 1929 ( Maldaner et al. 2018), Deltochilum (Deltohyboma) Lane, 1946 ( González-Alvarado and Vaz-de-Mello 2021), Agamopus Bates, 1887 ( Costa-Silva et al. 2022), and Dichotomius (Cephagonus) Luederwaldt, 1929 ( Nunes and Vaz-de-Mello 2020b) – see Cupello et al. 2023 for a comprehensive list. Many highly specious and problematics groups such as Uroxys Westwood, 1842 , Canthidium Erichson, 1847 and Ateuchus Weber, 1801 are still considered taxonomical gaps and are in need of revisions ( Cupello et al. 2023). As a result of this growing effort in understanding the New World diversity of Scarabaeinae , the number of revisions and the discovery of new species has grown steadily over the last three decades ( Cupello et al 2023).

One of the key factors promoting these taxonomic advances is the interest in using the group as bioindicators by ecologists focused on conservation biology (see Cupello et al 2023 for more information). This new interest not only pushed taxonomists to provide reliable identifications and identification tools for researchers from other fields (e.g., ecologists) but also the growing number of specimens collected by these professionals provide taxonomists with the means for resolving some major taxonomic gaps ( Cupello et al 2023).

Typically, Scarabaeinae are collected using pitfall traps baited with mammalian dung (i.e., cattle, human and pig), mushroom, decaying fruits as well as decaying carrion ( Halffter and Matthews 1966, Costa-Silva et al. 2018, Raine and Slade 2019). Recent studies have shown that flight interception is an efficient method for dung beetles, given their strong flying abilities, and some species are only sampled through pitfall or flight interception traps, with these two collection methods being complementary ( Puker et al. 2020, Ong et al. 2021, Bach et al. 2023).