A newly identified wasp species, Chrysonotomyia susbelli, has been discovered in Houston, Texas, marking the 18th new species identified by Rice University’s Scott Egan and his research team since 2014. The discovery, the fourth wasp species found on the university grounds in seven years, reveals the hidden world of parasitoid wasps and the intricate ecosystems that thrive outside our doors.
The Chrysonotomyia susbelli is a parasitoid wasp, about 1 millimeter long, that emerges from galls, or tumorlike growths created by the gall wasp Neuroterus bussae found on southern live oak leaves. The galls serve as microhabitats within which larvae feed, develop and pupate. The research team’s study was published in the journal ZooKeys on Sept. 18.
“Chrysonotomyia susbelli represents the sixth species of its genus described from North America and the first globally known to parasitize cynipid gall wasps,” said Egan, an associate professor of ecology and evolutionary biology.
The wasp was discovered and named by Brendan O’Loughlin, a Rice senior and the study's first author. “The wasp’s goldenrod color is almost identical to the official colors of Wiess College, my residential college,” O’Loughlin said.
To confirm the uniqueness of the species, the research team conducted a genetic analysis and a detailed study of the wasp’s physical features under a microscope. Its investigation also included a review of the historical literature to ensure that the species had not been previously described.
This research was complemented by DNA barcode data and observations of the wasp’s natural history, including host associations and a unique leaf-scanning behavior exhibited by female wasps. The researchers also modified the identification key of New World members, groups of species found exclusively in the Americas, to incorporate this new species.
Egan emphasized the importance of studying local biodiversity. “You don’t have to travel to a distant rainforest to find new and beautiful things — you just have to step outside and look,” he said.
The discovery hints at a previously unexplored ecological niche involving Chrysonotomyia parasitoids, cynipid gall wasps, and oaks, suggesting that there may be many more undiscovered species within this system.
“Generations of Chrysonotomyia susbelli have likely lived unnoticed on the oaks of Rice University since its founding,” Egan said.
Co-authors of the study include Pedro FP Brandão-Dias, Ph.D. graduate of ecology and evolutionary biology at Rice and current postdoctoral scholar at the University of Washington, and Michael Gates, parasitoid wasp specialist of the U.S. Department of Agriculture’s Systematic Entomology Laboratory at the Smithsonian National Museum of Natural History.