Abstract
Several populations of Eunotia serra Ehrenberg were examined from the eastern and central USA, revealing significant morphological differences from the different sites investigated. Populations from some sites have two rimoportulae per valve, as opposed to other sites where populations have one rimoportula per valve. This last observation raises the question about whether the number of rimoportulae is an important characteristic to use for distinguishing species of Eunotia Ehrenberg. It also raises interesting questions about the phylogenetic relationships between species of Eunotia and other taxa in the Eunotiophycidae D.G. Mann, especially with respect to the significance of rimoportulae in the evolution of the raphe.
Acknowledgements
We wish to thank Marina Potapova, Academy of Natural Sciences of Philadelphia for her assistance in this study, Steve Main at Wartburg College for his help with earlier SEM photographs, and the following persons for their assistance in the field: Alan B. and Ree Smith, Betsy and Amy Brant, Al and Dianne Bowser, and Rex Lowe. We acknowledge Bowling Green State University for use of their scanning electron microscope. Partial support for P.C. Furey was received from NSF funding awarded to Jill Welter [NSF-DEB 0950016] of St. Catherine University. Support to L.A. Brant was received by the Department of Earth Science and the Graduate College of the University of Northern Iowa through summer fellowships and professional development assignments.