Advisor: Harald Krenn

Master's Defensio

Thursday, March 30th 2023, 14:00 CET
SR 1.5, UBB
Djerassiplatz 1, 1030 Vienna

Abstract

Centipedes are known for their fearsome appearance due to their peculiar forcipules that are used in grabbing, restraining, and piercing their prey. These forcipules are evolutionary trans-formed locomotory legs that bear venom glands used to inject venom. In many arthropods, the cuticle of piercing and biting structures is incorporated with heavy element biomaterials to increase hardness and elasticity, and to minimize wear and tear. There is, however, no information about the presence of heavy element biomaterials in the cuticle of the piercing forcipule of centipedes. Specimen from all five centipede subtaxa (Scutigeromorpha, Lithobiomorpha, Craterostigmomorpha, Scolopendromorpha, and Geophilomorpha) were investigated with respect to cuticular components and reinforcements of their forcipules. Elemental cuticular components were investigated with energy-dispersive X-ray analyses. Using micro-CT analyses, the forcipules were investigated in terms of cuticular thickness and radiodensity. Furthermore, cuticular sclerotization gradients were analysed using confocal laser-scanning microscopy based on autofluorescence properties. Forcipular morphology is compared with that of serially homologous locomotory legs, to test whether reinforcements only occur in the weaponized forcipules or are a general feature of appendages. Experiments revealed an increasing sclerotization gradient towards the distal tarsungulum and an increased sclerotization of joints in all investigated taxa. Increased incorporation of zinc is present only in the tarsungulum of Craterostigmomorpha, Scolopendromorpha and Geophilomorpha. Addition-ally, sodium and chlorine gradients were found in the tarsungulum in epimorphic centipedes. These results support the hypothesis that in centipedes the forcipular tarsungulum corresponds to the tarsus and the pretarsal claw, and that taxon-specific modifications of the forcipule might correlate with environmental interactions.