title: Comparative morphology of the mouthparts of the megadiverse South African monkey beetles (Scarabaeidae: Hopliini): feeding adaptations and guild structure.
abstract: Although anthophilous Coleoptera are regarded to be unspecialised flower-visiting insects, monkey beetles (Scarabaeidae: Hopliini) represent one of the most important groups of pollinating insects in South Africa's floristic hotspot of the Greater Cape Region. South African monkey beetles are known to feed on floral tissue; however, some species seem to specialise on pollen and/or nectar. The present study examined the mouthpart morphology and gut content of various hopliine species to draw conclusions on their feeding preferences. According to the specialisations of their mouthparts, the investigated species were classified into different feeding groups. Adaptations to pollen-feeding included a well-developed, toothed molar and a lobe-like, setose lacinia mobilis on the mandible as well as curled hairs or sclerotized teeth on the galea of the maxillae. Furthermore, elongated mouthparts were interpreted as adaptations for nectar feeding. Floral- and folial-tissue feeding species showed sclerotized teeth on the maxilla, but the lacinia was mostly found to be reduced to a sclerotized ledge. While species could clearly be identified as floral or folial tissue feeding, several species showed intermediate traits suggesting both pollen and nectar feeding adaptations. Mismatches found between mouthpart morphology and previously reported flower visiting behaviours across different genera and species requires alternative explanations, not necessarily associated with feeding preferences. Although detailed examinations of the mouthparts allowed conclusions about the feeding preference and flower-visiting behaviour, additional morphological and behavioural investigations, combined with greater taxon sampling and phylogenetic data, are still necessary to fully understand hopliine host plant relationships, related to monkey beetle diversity.
authors.affiliation: Department of Integrative Zoology, University of Vienna , Vienna , Austria.
authors.forename: Florian
authors.initials: F
authors.lastname: Karolyi
authors.affiliation: Department of Integrative Zoology, University of Vienna , Vienna , Austria.
authors.forename: Teresa
authors.initials: T
authors.lastname: Hansal
authors.affiliation: Department of Integrative Zoology, University of Vienna , Vienna , Austria.
authors.forename: Harald W
authors.initials: HW
authors.lastname: Krenn
authors.affiliation: Kirstenbosh Research Center, South African National Biodiversity Institute, Cape Town, South Africa; Statistic in Ecology, Environment and Conservation, Department of Statistical Science, University of Cape Town, Rondebosh, Cape Town, South Africa.
authors.forename: Jonathan F
authors.initials: JF
authors.lastname: Colville
keywords: Flower visiting; Functional morphology; Guild structure; Hopliines; Monkey beetles; Mouthparts; Pollination
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