Cryptic diversity in Australian stick insects (Insecta; Phasmida) uncovered by the DNA barcoding approach.

The barcoding approach was applied to analyze 16 Australian morphospecies of the order Phasmida, with the aim to test if it could be suitable as a tool for phasmid species identification and if its discrimination power would allow uncovering of cryptic diversity. Both goals were reached. Eighty-two specimens representing twelve morphospecies (Sipyloidea sp. A, Candovia annulata, Candovia sp. A, Candovia sp. B, Candovia sp. C, Denhama austrocarinata, Xeroderus kirbii, Parapodacanthus hasenpuschorum, Tropidoderus childrenii, Cigarrophasma tessellatum, Acrophylla wuelfingi, Eurycantha calcarata) were correctly recovered as clades through the molecular approach, their sequences forming monophyletic and well-supported clusters. In four instances, Neighbor-Joining tree and barcoding gap analyses supported either a specific (Austrocarausius mercurius, Anchiale briareus) or a subspecific (Anchiale austrotessulata, Extatosoma tiaratum) level of divergence within the analyzed morphospecies. The lack of an appropriate database of homologous coxI sequences prevented more detailed identification of undescribed taxa.

Hardness in arthropod exoskeletons in the absence of transition metals.

The arthropod cuticle is a remarkable and versatile biological material commonly composed of chitin and proteins. Lessons can be learned from the way it is adapted to fit its functions. The larval jewel beetle, Pseudotaenia frenchi, demonstrates hardness in the cutting edge of the mandibles in excess of the mineralized carapace of stone crabs and compares favourably with some stainless steels. Yet this is a form of cuticle which is devoid of transition metals or mineralization. In seeming contradiction, the similarly dark coloured adult beetle mandibles contain the transition metal manganese, but are significantly softer. Energy dispersive X-ray analysis and infrared spectroscopy have been used to investigate the differences in composition of mandible cuticle of the adult and larval beetles.