To be or not to be: postcubital vein in insects revealed by microtomography

International audienceTo better understand insect evolution, fossils – mainly known by their wings – must be used as terminals in phylogenetic analyses. Such analyses are, however, rarely performed because of a lack of consensus on the homology of venation in insects. Authors do not agree with current concept on the exact number and the identity of the main veins. Here, we confirm the presence, questioned since the early twentieth century, of an independent main postcubital vein (PCu) between the cubital and anal veins (29 fossil and extant examined orders, >85% of observed insects). The vein PCu corresponds to the so-called vein 1A or first anal vein. It is easily identified by the unique shape of its bulla. It may have several branches, and be partially fused with the cubital and anal veins. Once the PCu vein identified, we reconsidered as an example the particular case of the Phasmatodea, showing that extant stick insects have a unique venation among insects, with a reduced median vein, and a simple cubital vein, adjacent or fused to the PCu. This study is a new approach towards resolving wing vein homology issues, crucial for future large-scale phylogenetic analyses in insects combining extant and extinct taxa

Synthesis and characterization of an n=6 Aurivillius phase incorporating magnetically active manganese

Epitaxial films of Bi7Mn3.75Ti2.25O21 were prepared to yield a previously unsynthesized material. The superlattice phase is produced by incorporating the magnetoelectric BiMnO3 into the perovskite substructure of the ferroelectric Bi4Ti3O12, a strategy which is hoped to yield previously undiscovered multiferroic materials. X-ray diffraction and transmission electron microscopy (TEM) confirm synthesis of an epitaxial n=6 Aurivillius phase. Magnetization measurements show ferromagnetic behavior with a Curie point of 55 K, but electronic polarization measurements show no remanent polarization. Rutherford backscattering spectrometry indicates a channeling minimum chi(min) of 22%, consistent with the high density of out-of-phase domain boundaries observed by TEM. (C) 2007 American Institute of Physics