It’s too fast to catch, spears smaller insects with spiny legs, and sings a song that mirrors the syllables of its name, “Ka-ty-did, Ka-ty-didn’t.” Its music is so catchy, it has even been used as the chorus of popular songs.
Listroscelidinae are a group of insectivorous katydid hunters from South America whose fast and aggressive behavior makes them difficult to capture, let alone identify. According to the authors of a recent PLOS ONE study, these Neotropical katydids have been understudied, partly because we haven’t been able to get our hands on them. However, the authors of this study managed to collect more than 100 specimens from one of the world’s most threatened ecosystems, the Brazilian Atlantic Forest.
They compared these new specimens to existing samples from museums by collecting DNA samples and creating simplified illustrations to document the differences between the physical characteristics in each species. In addition to measuring the phalluses and abdomens, they traced the placement of stridulatory files on their wings, shown in the image below, which katydids rub together to make noise. The different placement of these bands allowed the researchers to distinguish between related species.
After examining the physical characteristics and DNA samples, researchers were able to identify and name eight new species of Neotropical katydids, which have been very difficult to classify and have been re-categorized several times in the last century.
The most distinctive feature of these Neotropical katydids is their spiked legs, which they use to skewer and ensnare insect prey. A close relative of the Listroscelidinae, the Red-eyed Devil, has been documented performing the katydid hunt.
The authors caution that these species may be seriously endangered as they are found only in highly-preserved sections of this threatened forest. Identifying these species has helped reshape how researchers think about them, but there is still much research to be done on this group of Neotropical katydids, as long as researchers can catch up with them!
Citation: Fialho VS, Chamorro-Rengifo J, Lopes-Andrade C, Yotoko KSC (2014) Systematics of Spiny Predatory Katydids (Tettigoniidae: Listroscelidinae) from the Brazilian Atlantic Forest Based on Morphology and Molecular Data. PLoS ONE 9(8): e103758. doi:10.1371/journal.pone.0103758
Images: All images are from the article.