Ecological Risk Screening Summary - Marbled Aplexa (Stenophysa marmorata) - Uncertain Risk

Stenophysa marmorata, Marbled Aplexa, is an aquatic snail that is native to parts of South and Central America and the Caribbean. S. marmorata is a hermaphroditic species generally found in lentic habitats with macrophytes. This species has been introduced to multiple countries in Africa and a botanical garden in Europe, possibly through the aquatic plant trade. Populations have become established in the wild in multiple African countries. However, there is currently no information on the impact of these introductions. While S. marmorata has been reported from Texas, there is no specific distribution information available, and its current status is unknown. S. marmorata is a host of a parasitic trematode which has been known to cause cercarial dermatitis in humans. The History of Invasiveness for Stenophysa marmorata is classified as Data Deficient due to the lack of information regarding the impact of introduced populations. The climate matching analysis for the contiguous United States indicates establishment concern for this species, with the highest climate matches occurring along the Atlantic and Gulf coasts from New York to Texas. The Certainty of Assessment for this ERSS is classified as Low due to the lack of information on the invasive potential of S. marmorata and possible misidentifications that could affect understanding of the species range. The Overall Risk Assessment Category for Stenophysa marmorata in the contiguous United States is Uncertain.

Species that are considered uncertain risk need a more in-depth assessment beyond the Risk Summary to better define the species’ risk to U.S. environments.