Morphological variation and systematics of Canthon Hoffmansegg 1817, and related genera of new world Canthonini dung beetles (Coleoptera, Scarabaeinae)

Abstract

Morphological variation was examined in 65 species of Canthon Hoffmansegg and 31 species in 11 additional genera of the tribe Canthonini (Anisocanthon Martínez & Pereira, Canthonella Chapin, Cryptocanthon Balthasar, Deltochilum Eschscholtz, Hansreia Halffter & Martínez, Holocanthon Martínez & Pereira, Malagoniella Martínez, Megathopa Eschscholtz, Melanocanthon Halffter, Scybalocanthon Martínez, and Sylvicanthon Halffter & Martínez). Morphological characters were examined on a total of 306 specimens. Variation in head structures such as clypeus, eyes, labium. gula, and epipharynx is described. Thoracic structures examined include pronotum, proepimeron, prosternum, and posterior and medial tibiae. Additional structures examined were the elytra, pygidium, and male genitalia, including the sclerites and brushes of the internal sac. Cladistic analysis of 39 taxa and 82 characters resulted in eight most parsimonious cladograms. The consensus tree confirms that Canthon is polyphyletic. Characters mainly from the epipharynx support the clade where most of the genera of Canthonini included in the analysis, with the exception of Cryptocanthon and Canthonella, are grouped. The species of the subgenus Francmonrosia form a clade supported mainly by synapomorphies from the internal male genitalia. Species of the genus Scybalocanthon share four synapomorphies with Canthon sordidus. Although there are some supported groups, there is extensive homoplasy in the cladogram mainly for characters of external morphology. A majority of the synapomorphies correspond to characters from the internal structures such the epipharynx and the internal male genitalia. Therefore we consider the internal morphology to be more informative in defining natural groups within Canthonini.

Morphology and terminology of dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) male genitalia

“…8). This is seen in Coptorhina excavata Frolov, Akhmetova &Scholtz, 2008 andDicranocara Frolov &Scholtz, 2003. In the genital segment, which has a more quadrangular shape, the lateral plates are longitudinally located (Figs. 9, 10); in some species the extreme basal of the lateral plate can be curved as in Canthon quinquemaculatus Laporte, 1840 (Fig.11) and Anachalcos procerus Gerstaecker, 1874 (Fig.12).…”

“…85, 86), the rectangular shape is also observed in Anisocanthon villosus (Harold, 1868), Anomiopus sp., Sylvicanthon bridarollii (Martínez, 1949), and in different species of Canthon (Figs. 87-89) the parameres are more enlarged and with a notch in the ventral side of each paramere (Medina et al 2003).…”

“…This structure is present in the species of large New World deltochilines as The variation in the shape of the parameres can be quite large in genera with a large number of species, such as Canthon and Deltochilum. In Canthon, four different types of aedeagus by the shape of the parameres are recognized (Medina et al 2003). The triangular shape is the most common among the species studied, although with variations especially on the ventral face, which has some sinuosities, i.e., in the tribe Scarabaeini and in Sisyphus schaefferi (Linnaeus, 1758) (Fig.…”

Remarks about biology of Canthon rutilans Laporte, 1840 (Coleoptera: Scarabaeidae) with the first report of perching in a Brazilian Tropical Dry Forest

“…Mean body weights were 47 ± 13 mg in Milagres and 36 ± 14 mg in Senhor do Bomfim less than 59 mg found in the Atlantic Forest (Condé, 2008). Possible differences between Atlantic Forest and Caatinga specimens could be either geographical differences as Canthon species has morphological variations (Medina et al, 2003) or a consequence of less mammal faeces available (Hernández, 2007) that could limit development in the larval stages.…”

Phylogeny of the African ball-rolling dung beetle genus Epirinus Reiche (Coleoptera:Scarabaeidae:Scarabaeinae)

“…Although the global Scarabaeinae dung beetle fauna is divided into 12 tribes (Hanski and Cambefort 1991), some of these divisions lack phylogenetic support (Medina et al 2003;Philips et al 2004;Monaghan et al 2007;Davis et al 2008;Sole and Scholtz 2010). The current classification is considered to be based on two large 'monophyletic' groups (Cambefort 1991): 1), one containing six tribes of "tunnellers" with Dichotomiini being basal; and 2), the other consisting of six tribes of "rollers"…”