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Texas Invasive Species Institute

Texas Invasive Species Institute

New Guinea Flatworm

Platydemus manokwari

Class: Trepaxonemata
Order: Neoophora
Family: Geoplanidae

Platydemus manokwari

Source: https://doi.org/10.7717/peerj.297/fig-1


The New Guinea flatworm is a dark-brown predatory worm that was first discovered on the island New Guinea. As its name suggests, it is a flat, worm-looking invertebrate. Platydemus manokwari ranges from 1.6-2.6 inches. Both ends of the animal look similar, but the end with the head is narrower and has two eyespots. The underside of this animal is a pale tan and the upper-side has a faint stripe down it.  

Ecological Threat

This species is a predator of snails. It uses a white pharynx like a feeding tube and is able to drain snails completely. Despite seeming like harmless, slimy creatures, snails are an important link in the food chain and ecosystem. They have been imported in other nations to control the Giant African snail! A snail that can grow up to 7 inches in length! In several Pacific Islands, researchers have noticed a significant decrease, even extinction events, of many land snails. They have been documented to climb up trees following the snail trails of their prey.

This small flatworm also poses a threat to vertebrate animals like humans and other mammals by carrying parasites. Platydemus manokwari is known to be a paratenic host of the Rat Lungworm, Angiostrongylus cantonensis (please refer to our Species Page). Since the flatworms feed on snails that are often intermediate hosts of the Rat Lungworm, the flatworms are able to help spread the nematode parasite around. If they are infected with the parasite, they can increase an animals or humans ability to encounter the Angiostrongylus parasite.


**If you ever see these specimens, please do not pick them up with your bare hands. Use gloves or disposable forceps**


Platydemus manokwari is a nocturnal worm. It has been observed to not only eat snails but also earthworms and isopods. They are also known to participate in gregarious attacks (ie: many attack the same prey).  


In 2015, the presence of the New Guinea flatworm was confirmed in Miami, Florida. Since it has a preference for sub-tropical areas and a tolerance for temperate zones, it could easily be throughout the Southeastern United States.

Native Origin

New Guinea

Current Location

U.S. Present: Florida and Puerto Rico

    TISI has collected specimens at Lamar State College campus and are currently collecting molecular data to confirm the species of flatworm.

    We hope to collect any potential specimens, but this is not always possible. Please feel free to email TISI with photos of any potential sightings.

U.S. Habitat: Since snails are widespread in various habitats, especially in subtropical and Tropical regions of the United States, the Southeastern United States are the most susceptible. Platydemus manokwari is already established in Florida and Puerto Rico.


Unfortunately, there are no known predators of this flatworm, so no bio control can be implemented for its management. This soft-bodied worm could be susceptible to salt, or slug repellent. However, slug repellent is very toxic to dogs and cats, so please apply with caution.


de Beauchamp, P (1962). Platydemus manokwari n. sp., planaire terrestre de la Nouvelle-Guinée Hollandaise. Bulletin de la Société Zoologique de France. 87: 609–615.

Justine, J. L., Winsor, L., Barrière, P., Fanai, C., Gey, D., Han, A. W. K., ... & Philippart, D. (2015). The invasive land planarian Platydemus manokwari (Platyhelminthes, Geoplanidae): records from six new localities, including the first in the USA. PeerJ, 3, e1037.

Muniappan, R., Duhamel, G., Santiago, R. M., & Acay, D. R. (1986). Giant African snail control in Bugsuk island, Philippines, by Platydemus manokwari. Oleagineux, 41(4), 183-188.

Sugiura, S., & Yamaura, Y. (2009). Potential impacts of the invasive flatworm Platydemus manokwari on arboreal snails. Biological invasions, 11(3), 737-742.

Internet References




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