Morphometry and feeding behaviour in two sympatric orthopterans in the Kalahari (Namibia): The trait as you like it

High entomological trait variability is supposed to reflect a combination of intra- and inter-phenotype signals. These functional signals are mirroring different behaviours and feeding habits. Our main aim was to assess if the trait distribution of body measurements of two sympatric species is further more significantly influenced by gender (intraspecific variance) or by species (interspecific variance). To achieve this, we collected in Namibia (Africa) tettigoniids belonging to the sympatric species Acanthoplus discoidalis and Acanthoplus longipes. We measured in the field the total body length, the maximal pronotal width and length, and the third pair of legs (femur and tibia) of 106 adults. We derived the body mass and volume from empirical length and width values of the sampled specimens and compared them with literature data on African tettigoniids. The discriminant analysis shows that at species level the locomotory traits as captured by tibia and femur lengths and the size traits as captured by body and pronotal lengths account for 99% of the total variance and clearly separate the two species. However, the intraspecific trait distributions between males and females are small in contrast to the interspecific trait distributions. We explain this latter phenomenon as consequence of dietary differences due to nitrogen contents of the host plants between A. discoidalis and A. longipes.