Last month, Michael Caterino and Alexey Tishechkin, both researchers at the Santa Barbara Museum of Natural History, officially identified 138 new beetle species living throughout Central and South America, taking the total number of species to nearly 200. Originally discovered more than 150 years ago by French entomologist Sylvain Auguste de Marseul, this group of histerid or “clown” beetles — possibly nicknamed for their flat legs, similar to clown shoes — previously included just 25 separate species, so their findings are significant both for showing the abundance of these beetles as well as revealing the potential biodiversity issues in tropical areas where they are found.
The work was funded by the National Science Foundation as part of “large-scale” study of beetle diversity involving more than 4,000 specimens from natural history museums all over the world. The clown beetles, which tend to prefer tropical climates, can occasionally be found in North America, though such instances are “scant,” according to the research, which was published in the journal ZooKeys.
Caterino and Tishechkin gathered beetles in Mexico, Belize, Costa Rica, Panama, Brazil, Ecuador, Peru, and Argentina, where they mostly used “passive flight interception traps.” Said Tisheckhin, “Being in the field in these amazing places is one of the most exciting parts of a study like this.” Caterino noted that “While most of my work at the Santa Barbara Museum of Natural History has focused on California beetles, I have also always had this more particular interest in clown beetles, and in fact I’m one of only about six researchers in the world actively working on this group.”
Since the beetles are nearly identical externally, researchers had to rely on the analysis of the male genitalia of the beetles to accurately identify many of the new species. “Superficially, they don’t look all that exciting,” explained Caterino. “But once we started looking at them closely, we began to see subtle differences in body sculpturing, as well as in the male genitalia. Entomologists are somewhat notorious for their interest in genitalia,” he admitted. “It’s incredible how different the genitalia of species that are externally indistinguishable can be.”
Clown beetles are best known for their use in forensic investigations, as they show up to eat on the maggots and other bugs that feed on dead bodies and can be used to determine time of death. But in nature, they also feed on small arthropods that live in areas with decaying vegetation and leaf litter, forest floor habitats that are often overlooked by science, so this discovery of new species helps shed more light on those ecosystems. “Clown beetles are not one of the most beloved families of beetles,” said Caterino, “in part because most are very small and difficult to study, also in part because many of them occur in pretty nasty habitats, like decaying animals and dung.”
“We all know that forests in the tropics are disappearing,” said Caterino. “But we only have the faintest idea of how much biodiversity is disappearing with them. Studies like this are critical to seeing where the greatest diversity is and how to best protect it.”