Morphology of the third instar larva of Colobopterus quadratus (Coleoptera: Scarabaeidae: Aphodiinae) using scanning electron microscopy

Abstract

Aphodiinae are a large cosmopolitan subfamily of Scarab beetles (Scarabaeoidea: Scarabaeidae), playing an important role during dung decomposition. Many aspects, especially immature stages, of these dung beetles have not yet been recorded due to their comparative small body sizes and lacking of striking rolling behavior. In this study, the third instar larva of Colobopterus quadratus is morphologically described using scanning electron microscopy. The larva is atypical for the combination of following morphological features: (a) the larval antennae are five‐segmented; (b) the clypeus bears 4 minute protuberances on dorsal surface; (c) the epitorma on epipharynx is ventrally protuberant; (d) the scissorial area of left mandible is broad and blade‐like; (e) the raster is furnished with six glabrous protuberances and two rows of pali arranged in V‐shape. Some significant ultra‐morphological features were discovered in larval Aphodiinae for the first time. The presence of blade‐like incisor on the left mandible implies the potential root cutting ability.

Morphological description of the third instar larva ofLasiotrichius succinctus hananoi(Sawada) (Coleoptera: Scarabaeidae: Cetoniinae: Trichiini), using scanning electron microscopy

“…Epipharynx are quite diverse and playing a key role in larval taxonomy in Scarabaeidae (Böving, 1936;Hayes, 1929;Ritcher, 1966;Zhang, 1984). In Cetoniinae, the larval epipharynx are usually trilobed and devoid of helus, similar to the dung feeding species in Geotrupidae and Aphodiinae (Li, Lu, Fang, & Jiang, 2019;Verdú, Galante, Lumaret, & Cabrero-Sañudo, 2004). In Trichiini, the larval haptomeral process is absent in Clastocnemis and Gnorimus subopacus (Jerath & Unny, 1965;Shabalin & Bezborodov, 2009), and present in Trichius, Stripsipher, Paratrichius, and G. nobilis (Sawada, 1991;Šípek, Ricchiardi, & Perissinotto, 2012).…”

“…Besides the haptomeral process, the arrangement of stout setae is also different on specific or generic level, although they were not well illustrated under light microscopy (Shabalin & Bezborodov, 2009). SEM contributes significantly for the larval taxonomy in Scarabaeoidea (Fang, Li, & Jiang, 2018;Li et al, 2019;Qu, Jia, & Jiang, 2019;Šípek, Ricchiardi, & Perissinotto, 2012;Sousa et al, 2018).…”

“…SEM contributes significantly for the larval taxonomy in Scarabaeoidea (Fang, Li, & Jiang, 2018; Li et al, 2019; Qu, Jia, & Jiang, 2019; Šípek, Ricchiardi, & Perissinotto, 2012; Sousa et al, 2018). In this study, we use SEM to better illustrate the surface decorations of larval mouthparts, especially on epipharynx and mandibles, which are not clearly described under light microscopy (Sawada, 1991; Shabalin & Bezborodov, 2009).…”

“…Most of the scarab larvae that inhabiting underground or in the decaying wood are usually devoid of visual organ (Ritcher, 1966;Zhang, 1984), which is a similarity shared by Lucanidae, Aphodiinae, Melolonthinae, Rutelinae, Dynastinae, and some Cetoniinae (Fuhrmann, 2013;Li et al, 2019;Micó & Galante, 2003a;Qu et al, 2019;Rodrigues, Fuhrmann, Gomes, & Amaro, 2017). However, stemmata are abnormally present in L. succinctus hananoi, similar to the species in some other cetoniine genera, including Coelocorynus, Inca, Clastocnemis, Gnorimus, Marmylida, Diplognahta, Dicronocephalus, Hypselogenia, Neoscelis, Amithao, Gymnetis, Anochilia (Jerath & Unny, 1965;Morón & Arce, 2002;Nogueira, Morón, Fierros-López, & Navarrete-Heredia, 2004;Oberholzer, 1959;Randriamanantsoa, Aberlenc, Ralisoa, Ratnadass, & Vercambre, 2010;Shabalin & Bezborodov, 2009;Šípek et al, 2008;Šípek et al, 2009;Sousa et al, 2018).…”

Habitat divergence shapes the morphological diversity of larval insects: insights from scorpionflies

“…Because they never expose to the light on the soil, it is unnecessary for the larvae of Panorpa and Neopanorpa to adopt camouflage strategies. As a result, these larvae are grossly pale, similar to soil-inhabiting white grubs of Scarabaeoidea 69–71 and stem-boring weevils of Curculionidae in Coleoptera 72 .…”