A team of entomologists from the University of Toronto Mississauga, Canada, and the University of Lincoln’s Joseph Banks Laboratories, UK, has discovered a new species of leaf-mimic bushcricket living in the Andes, from Western Ecuador to the middle Central Cordillera in Colombia. The team has also studied the wing mechanics and resonances of the new species, named Typophyllum spurioculis. The results are published in the Zoologischer Anzeiger, a Journal of Comparative Zoology.
Typophyllum spurioculis mimics dead leaves to the point of near invisibility and has vivid orange eye spots on its legs and wings. The species sings so loud humans can hear it, according to the study.
To uncover the biophysical properties, behavior and ecology of the insect, University of Lincoln student Andrew Baker and colleagues produced the anatomical description of Typophyllum spurioculis using illustrations to infer the arrangement of veins in its wing, and examined the sound producing structures of the wings in the males using advanced bioacoustics research techniques.
“We found that when the males sing the entire wing resonates at the frequency of the call — something which does not happen in other species of bushcrickets,” the researchers said.
“Usually the resonating call of a bushcricket is localized to the region where the sound originates, and is created by a plectrum on the right wing being plucked by a tooth-covered file on the left wing to produce sound vibrations.”
“The plectrum is connected to a drum-like structure that works as a speaker to radiate and amplify the signal.”
“Significantly, we found that in Typophyllum spurioculis, it is actually the whole wing, which resonates and amplifies the generated sound signals.”
“The unusual whole-wing-resonance might partly explain why the male’s song is particularly loud and also in the range audible to the human ear, while its closest relatives are all singing at higher frequencies which we cannot detect with our ears,” added Dr. Fernando Montealegre-Z, also from the University of Lincoln.
Dr. Montealegre-Z, Baker and co-authors also found that the females are larger than the males and also remain silent, with only the males employing their unusual acoustic abilities.
In another twist on the conventional rules of nature, the scientists found that Typophyllum spurioculis’ bright orange spots are not to deter predators, but instead are likely to be involved in visual communication between the sexes.
Andrew Baker et al. 2017. Wing resonances in a new dead-leaf-mimic katydid (Tettigoniidae: Pterochrozinae) from the Andean cloud forests. Zoologischer Anzeiger, a Journal of Comparative Zoology 270: 60-70; doi: 10.1016/j.jcz.2017.10.001