title: Structural plastron in relict Gondwanan moss bugs (Hemiptera: Coleorrhyncha: Peloridiidae) and its possible implications for systematics, biogeography and for the standard definition of plastron.
abstract: Peloridiidae are a family of small hemipterans who live and feed on bryophytes of temperate forests in some regions of the Southern Hemisphere. They are often submerged in water and would require adaptations for respiration to tolerate periods of inundation. Here we report water-repelling cuticular structures on the tergites of thorax and abdomen and on the ventral surface of tegmina in Peloridiidae. Our observations show that these body parts can hold an air bubble or layer which is in contact with spiracles. Thus, the described structures comply with the definition of a structural plastron. The micromorphology of these structures was studied with a SEM on adults and nymphs of several species and their hydrophobicity was tested in two species with a contact angle goniometer. Possible implications for the standard plastron definition are discussed, as well as its significance for systematics, origin and biogeography of the group.
authors.affiliation: Staatliches Museum für Naturkunde Karslruhe, Erbprinzenstrasse 13, D-76133 Karlsruhe, Germany; Museum für Naturkunde - Leibniz-Institute for Research on Evolution and Biodiversity, Invalidenstrasse 43, 10115 Berlin, Germany. Electronic address: viktor.hartung@mfn-berlin.de.
authors.forename: Viktor
authors.initials: V
authors.lastname: Hartung
authors.affiliation: Institute for Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany. Electronic address: ingo.medebach@kit.edu.
authors.forename: Ingo
authors.initials: I
authors.lastname: Medebach
authors.affiliation: Institute for Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany. Electronic address: stefan.walheim@kit.edu.
authors.forename: Stefan
authors.initials: S
authors.lastname: Walheim
mesh_terms: D000222:Adaptation, Physiological; D063147:Animal Distribution; D000818:Animals; D006430:Hemiptera / Q000502:physiology / Q000648:ultrastructure*; D057927:Hydrophobic and Hydrophilic Interactions; D008297:Male; D008855:Microscopy, Electron, Scanning; D009758:Nymph / Q000648:ultrastructure
keywords: Contact angle; Cuticular microsculpture; Non-wettable surface; Peloridiidae; Plastron; Scanning electron microscopy