Wednesday, July 5, 2017

Source of the biologically invasive snail, Physa acuta

see note below*

  Physa acuta (also known as Physella acuta) is a well-known biologically invasive species that is now distributed over much of the world.  It was originally described by Draparnaud in 1805 from the Garonne River in France and initially thought to be indigenous to Europe.  Beginning in 2002, reports were made that perhaps the species was not native to Europe, but was native to North America making it an invasive species to Europe and Asia.  Recently, Lydeard et al. (2016) ( in the journal Malacologia, synthesized available reproductive, anatomical, fossil, and phylogenetic data and provided a compelling case that the species is indeed indigenous to North America and was introduced and described in France.

Recently, Maxim Vinarski, added considerable knowledge on the biologically invasive history of P. acuta in a paper published in Biological Invasions (  Vinarski surveyed a range of literary sources and examined molluscan collections to determine the first record of P. acuta in the countries of Europe, Transcaucasia, and Central Asia and trace their route of invasion.  Interestingly, he determined that the earliest records of P. acuta in the New World can be traced back to 1742 suggesting that the species may have gained a stronghold sometime possibly in the 17th century.  He hypothesized that its introduction was due either to accidental transport by humans or long-distance dispersal.  The continued spread throughout the Palearctic appears to be due to anthropogenic factors.

Vinarski’s research has really shed considerable light on the spread of a problematic, biologically invasive mollusk species.
Literature Cited

Lydeard, C., D. Campbell, and M. Golz.  2016.  Physa acuta Draparnaud, 1805 should be treated as a native of North America, not Europe.  Malacologia 59(2):347-350.

Vinarski, M. V.  2017.  The history of an invasion: phases of the explosive spread of the physid snail Physella acuta through Europe, Transcaucasia and Central Asia.  Biol. Invasions 19:1299-1344.

*The Figure is a 'portrait' of a giant specimen of P. acuta from thermal waters (Bad Villach) of Austria. In Central Europe (Poland, Austria) this species sometimes produces such thermal races characterized by enlarged shell size. It was once described as a species 'variety': Physa acuta var. thermalis. The shell is from the Natural History Museum of Vienna collection.