Concerning flatworm species discovered invading backyards in Southern U.S.

PARIS — A team of international researchers has uncovered a new species of land flatworm in the United States, adding to the growing list of invasive species in the country. The flatworm, named Amaga pseudobama, was found in plant nurseries across several southern states, raising concerns about its potential spread and impact on local ecosystems.

The discovery, detailed in a recent study published in the journal PeerJ, highlights the ongoing challenges posed by invasive species and the importance of vigilant monitoring and identification efforts. The new flatworm species bears a striking resemblance to other known invasive flatworms, making it a stealthy invader that could easily go unnoticed.

Lead researcher Jean-Lou Justine and his colleagues first encountered the mysterious flatworm in 2020 when specimens were found in a plant nursery in Kinston, North Carolina. Initially, the researchers thought they had stumbled upon Obama nungara, a well-known invasive flatworm species from South America that has already made its way to Europe. However, closer examination and DNA analysis revealed a surprising twist – this was an entirely new species.

The newly discovered Amaga pseudobama is a small, dark brown flatworm with a pale stripe running down its back. It measures about 19-28 millimeters in length, making it the smallest known species in its genus. Despite its diminutive size, the flatworm’s potential impact on local ecosystems could be significant.

Land flatworms are predators that feed on soil-dwelling invertebrates like earthworms, slugs, and snails. When introduced to new environments, they can disrupt the delicate balance of soil ecosystems, potentially affecting plant growth and soil health. The concern is amplified by the fact that Amaga pseudobama seems to be spreading rapidly across the southern United States.

The research team found evidence of the flatworm’s presence not only in North Carolina but also in Florida and Georgia. What’s more, citizen science observations suggest it may have already reached other states, including Texas and California. This wide distribution indicates that the invasion likely began more than a decade ago, giving the species ample time to establish itself across a broad geographic range.

One of the most intriguing aspects of this discovery is how easily Amaga pseudobama can be mistaken for other flatworm species. Its appearance is remarkably similar to two other invasive flatworms: Obama nungara and Geoplana arkalabamensis. This resemblance poses a significant challenge for identification, especially when relying on photographs from citizen scientists.

To definitively identify Amaga pseudobama, the researchers had to delve deep into its anatomy and genetics. They performed detailed analyses of the flatworm’s internal structures, including its reproductive organs, and sequenced its mitochondrial genome. These studies not only confirmed that it was a new species but also provided valuable insights into its relationship with other flatworm species.

The genetic analysis revealed that Amaga pseudobama is closely related to Amaga expatria, another invasive flatworm species found in the Caribbean. This finding suggests that the two species may have a common origin, possibly in South America, and have independently made their way to different parts of the world through human activities.

As global trade and travel continue to facilitate the spread of organisms across continents, the risk of invasive species introductions remains high. Land flatworms like Amaga pseudobama are particularly prone to human-mediated dispersal, often hitching rides in potted plants or soil.

The researchers emphasize the importance of early detection and proper identification in managing invasive species. They call for more comprehensive surveys and improved molecular tools to quickly and accurately identify new arrivals before they have a chance to establish and spread.

For gardeners and plant enthusiasts, the study serves as a reminder to be cautious when acquiring new plants, especially from areas where invasive flatworms have been reported. Carefully inspecting plants and soil before bringing them home can help prevent the inadvertent spread of these and other invasive species.

As research continues, scientists hope to gain a better understanding of Amaga pseudobama’s ecology, life cycle, and potential impacts on native ecosystems. This knowledge will be crucial in developing effective strategies to manage and potentially control its spread.