title: One proboscis, two tasks: adaptations to blood-feeding and nectar-extracting in long-proboscid horse flies (Tabanidae, Philoliche).
abstract: Female Pangoniinae in the tabanid fly genus Philoliche can display remarkably elongated proboscis lengths, which are adapted for both blood- and nectar-feeding. Apart from their role as blood-sucking pests, they represent important pollinators of the South African flora. This study examines the morphology of the feeding apparatus of two species of long-proboscid Tabanidae: Philoliche rostrata and Philoliche gulosa - both species display adaptations for feeding from a diverse guild of long-tubed flowers, and on vertebrate blood. The heavily sclerotised proboscis can be divided into two functional units. The short, proximal piercing part is composed of the labrum-epipharynx unit, the hypopharynx and paired mandible and maxilla. The foldable distal part is composed of the prementum of the labium which solely forms the food canal and is responsible for nectar uptake via the apical labella. The proboscis works as a drinking straw, relying on a pressure gradient provided by a two-part suction pump in the head. Both proboscis and body lengths and suction pump dimensions show a significantly correlated allometric relationship with each other. This study provides detailed insights into the adaptations for a dual diet using an elongated sucking proboscis, and considers these adaptations in the context of the evolution of nectar feeding in Brachycera.
authors: Department of Integrative Zoology, University of Vienna, Faculty of Life Science, Althanstrasse 14, 1090 Vienna, Austria. Electronic address: florian.karolyi@univie.ac.at.
authors: Florian
authors: F
authors: Karolyi
authors: South African National Biodiversity Institute, Kirstenbosch Research Centre, Private Bag X7, Claremont, Cape Town, South Africa. Electronic address: jonathan.colville@gmail.com.
authors: Jonathan F
authors: JF
authors: Colville
authors: VetCore Facility for Research, University of Veterinary Medicine, Vienna, Austria. Electronic address: stephan.handschuh@vetmeduni.ac.at.
authors: Stephan
authors: S
authors: Handschuh
authors: Department of Theoretical Biology, University of Vienna, Faculty of Life Science, Althanstrasse 14, 1090 Vienna, Austria. Electronic address: brian.metscher@univie.ac.at.
authors: Brian D
authors: BD
authors: Metscher
authors: Department of Integrative Zoology, University of Vienna, Faculty of Life Science, Althanstrasse 14, 1090 Vienna, Austria. Electronic address: harald.krenn@univie.ac.at.
authors: Harald W
authors: HW
authors: Krenn
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001769:Blood; D004175:Diptera / Q000033:anatomy & histology* / Q000502:physiology / Q000648:ultrastructure; D005247:Feeding Behavior; D005260:Female; D008855:Microscopy, Electron, Scanning; D057048:Plant Nectar; D013019:South Africa; D055114:X-Ray Microtomography
chemical_list: D057048:Plant Nectar
keywords: Blood sucking; Diptera; Functional morphology; Mouthparts; Nectar-feeding; Philoliche