POSSIBLE HYBRIDIZATION BETWEEN GRAPTEMYS PSEUDOGEOGRAPHICA AND       G. 
OUACHITENSIS ALONG THE CEDAR RIVER, IOWA AND THE MISSISSIPPI RIVER
      
Andrew Huck, James Lamer, Sean Jenkins, Michael Romano

Western Illinois University Department of Biological Sciences Macomb, IL 
61455
      
Graptemys ouachitensis (Ouachita Map Turtle) were once considered a 
subspecies of G. pseudogeographica (False Map Turtle) until Vogt elevated it 
to full species level in 1993.  It was mentioned that the two species would 
hybridize and that the resulting offspring would look intermediate in 
appearance between the two species. Another study in 1994 by Lamb et al. 
using mtDNA placed G. ouachitensis as a subspecies of G. pseudogeographica.  
      
In 2005, a study was done on the Cedar River, Iowa to assess turtle 
diversity.  Turtles were trapped at two sites; one on the upper Cedar River 
near Waverly, IA and the other lower Cedar River site was near Moscow, IA.  
All map turtles captured at the upper Cedar River site were identified as G. 
pseudogeographica based on appearance.  Map turtles captured at the lower 
Cedar River site had an appearance in between G. pseudogeographica and G. 
ouachitensis.  G. pseudogeographica are distinguished from other map turtles 
by a yellow backwards L or swoosh behind the eye.  There are no large 
blotches or spots on the head.  G. ouachitensis are distinguished from other 
map turtles by three blotches on the head.  There is a yellow backwards L or 
swoosh behind the eye (larger than G. pseudogeographica) a spot below the 
eye, and a spot below the mouth line.  The eyes are also yellow whereas the 
eyes of G. pseudogeographica are more green.
      
In 2006, a genetic study was conducted at the previous two sites and also on 
the Mississippi River in pool 13 (Sabula IA) and pool 19 (Keokuk, IA).  G. 
pseudogeographica was captured at the upper Cedar River site and at the 
Mississippi River pool 13 site, G. ouachitensis was captured at the 
Mississippi River pool 19 site, and an intermediate between G. 
pseudogeographica and G. ouachitensis was captured at the lower Cedar River 
site.  Morphological measurements were taken along with tail tissue for 
microsatellite analysis.  Conclusions about hybridization between G. 
pseudogeographica and G. ouachitensis will be presented based upon 
morphological and genetic data.  These data will be used to assess the 
taxonomic status of G. ouachitensis.  
      
Keywords:  Graptemys pseudogeographica, Graptemys ouachitensis, 
hybridization, microsatellite, Cedar River, IA