Some native (C. integra, A. limosa) and invasive (B. tentaculata, P. antipodarum) species that are hard to tell apart. Shells are not identical in scale.

Go back to key

Bithynia tentaculata

Cincinnatia integra

Amnicola limosa

Potamopyrgus antipodarum

http://fl.biology.usgs.gov/Nonindigenous_Species/New_Zealand_Mudsnail/P_antipodarum6a.gif

http://www.ispot.org.uk/sites/default/files/imagecache/preview/images/5129/aeb1719db8db044ba0960cf24ad77b21.jpg?nav=related

Potamopgyrus antipodarum Operculum

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Comparison of Fontigens nickliniana and Potamopyrgus antipodarum

Fontigens nickliniana Potamopyrgus antipodarum
drawing of Fontigens nickliniana

  • Whorls are more rounded, almost shouldered, sutures more deeply incised, resulting in a bigger “gap.

  • Spire is more rounded, less pointed

  • Aperture is oval

  • Aperture lip is reflected only slightly at base of lip.

  • Whorls are less rounded, sutures less incised, resulting in a smaller “gap.”

  • Spire is more pointed

  • Aperture is not perfectly oval, it is drawn up to a point forming an angle, resulting in almost a teardrop shape

  • Aperture is reflected around most of the lip except at the very top.

  • Usually a brown-reddish rim of periostracum around the whitish color of the apertural lip.
Image on the Left from the Encyclopedia of life. Image on the R from Burch 1980. Image on the L from report to US Army by Daniell Cosier, Daniel Molloy (NY State Museum) and David Richards (Montana State University). Report includes many excellent images including dissections.