Cuticular microstructure of Australian ant mandibles confirms common appendage construction

Abstract

Exoskeletons characterise Arthropoda and have allowed the morphological and taxonomic diversity of the phylum. Exoskeletal sclerotisation occurs in genetically designated regions, and mandibles represent one such area of high sclerotisation. Mandible morphology reflects dietary preferences and niche partitioning and has therefore been well documented. However, mandibular cuticular microstructure has been under‐documented. Here we use scanning electron microscopy to explore mandible microstructure in four disparate Australian Formicidae taxa (ants) with different life modes and diets: Camponotus nigriceps, Iridomyrmex purpureus, Odontomachus simillimus and Rhytidoponera aciculata. We test the hypothesis that mandible construction is highly conserved across these species, as would be expected for arthropod cuticle. We show broadly similar mandible microstructure but report that pore canals and cuticular indentations are not ubiquitous among all studied taxa. Our preliminary results demonstrate that ant taxa have morphologically plastic mandibles with a highly conserved construction, potentially reflecting an interesting record of evolutionary stasis.