Passalidae Leach, 1815

Passalidae Leach, 1815 View in CoL

Fig. 4M

Diagnosis. One of the greatest peculiarities of the family is the undoubtedly remarkable morphological homogeneity. Most of species share the same basic morphological plan, which is further accentuated by a very rare visible sexual dimorphism ( Boucher 2006). Passalidae are represented by individuals with medium to large size (13–80 mm), morphologically similar to some Lucanidae . However, this group can be easily distinguished from other families of Scarabaeoidea by having the following set of characters: strongly sclerotized body, with shiny black color, dorsoventrally flattened, elytra completely covering the abdomen and distinctly striated with evident punctations; prothorax separated from the elytra by a long pedunculated mesonotum, where the visible scutellum is located anteriorly and below the frontal edge of the elytra. Prognathous head with robust and strongly sclerotized mandibles having a complex dentition system; labrum large and rigid, spatulate, prominent and retractable that slides almost entirely into the oral cavity; ligula exposed, fully sclerotized, relatively large and located in front of the mentum; hypostomal process always developed, taller and longer than in other Scarabaeoidea . Dorsal region of head provided with several integumentary structures more or less concave or convex, unique in Passalidae .

Remarks. Passalidae , with about 1,000 valid species, are a relatively small group when compared to the other families of Scarabaeoidea . These wood-degrading beetles occur essentially in the Pantropical area, with a few species present in the Nearctic ( Reyes-Castillo 1970, Boucher 2006).

Passalidae View in CoL are subdivided into two subfamilies: Aulacocyclinae View in CoL (Indo-Malo-Australian) and Passalinae (Pantropical) ( Boucher 2006) View in CoL . With regard to the American Passalinae View in CoL , the group is represented by two American endemic tribes: Proculini with 20 genera and Passalini View in CoL with 14 genera, together comprising about 50% of global passalid diversity ( Boucher 2006, Beza-Beza et al. 2020, Jiménez-Ferbans et al. 2022). In the Brazilian territory, Passalidae View in CoL are the third most diverse family with about 110 species ( Table 2) belonging to 12 genera, three from Proculini and nine from Passalini View in CoL ( Bevilaqua and Vaz-de-Mello 2023).

The most specious and contentious genus within the family is Passalus Fabricius, 1792 View in CoL , which is undeniably polyphyletic ( Boucher 2015, Bevilaqua and Fonseca 2020). The lack of clear delimitation further exacerbates the disparity in species numbers within this genus compared to other genera in the family. Although a more recent proposal for the classification of Passalini View in CoL and Passalus View in CoL , based on a phylogenetic analysis incorporating morphological and molecular characters has been put forth ( Jiménez-Ferbans et al. 2022), we adhere to the hypotheses proposed by Boucher (2015). These hypotheses validate some genera previously treated as synonyms or as a subgenus of Passalus View in CoL , which remains a polyphyletic genus awaiting further division. Veturius Kaup, 1871 View in CoL , the second most diverse genus in the family, is indeed the largest monophyletic group at the genus level ( Boucher 2006, Boucher and Salazar 2018).

In Brazil, the composition of the family is as follows: within Passalini , there are nine genera present in the country. Passalus , the most prominent genus, boasts 36 species and four subspecies. Pertinax Kaup, 1869 , follows with 17 species and one subspecies; while Paxillus MacLeay, 1819 , contributes nine species. Spasalus Kaup, 1869 , is represented by seven species, Rhagonocerus Kaup, 1871 , by five species, and Passipassalus Fonseca & Reyes-Castillo, 1993 , includes three species. Neleuops Kuwert, 1891 , Ptichopus Kaup, 1869 , and Toxeutotaenius Kuwert, 1896 , each encompass two species.

For Proculini, the largest genus is Veturius with 22 species, follow by Popilius Kaup, 1871 , with seven species, and Verres Kaup, 1871 with a single species.

Taxonomic knowledge about the Brazilian Passalidae fauna is dispersed in several works. However, it is possible to highlight as the main ones, the works of Luederwaldt (1931a, 1934a, 1934b, 1941) which is still considered the most complete work on Brazilian Passalids, the description of Passipassalus by Fonseca and Reyes-Castillo (1993), the review of the Brazilian species of Paxillus by Mattos and Mermudes (2013), and Boucher et al. (2016) for Veturius . For summaries of local fauna and/or descriptions of new taxa there are the works of Fonseca (1988), Bevilaqua and Fonseca (2019, 2020) for Amazonian fauna and Mattos and Mermudes (2014, 2015, 2016, 2018) for the fauna of the south and southeast regions of the Atlantic Forest. With advances in research, the number of species and the level of understanding of Brazilian species will increase in the coming years.