Historically, morphological techniques for species identification were the leading diagnostic methodology, however, the increased usage of genetic techniques has led to a decrease in reports of morphometrics. The decrease in morphological reports increases the chance of missing diagnostic morphometrics. The three studies described herein used morphological and genetic diagnostic methods to identify trematodes from five families in order to improve genetic and morphological information for trematode species identification.

The first study identified ten species of trematodes from intestines of waterbirds previously collected from Lake Winnibigoshish, Minnesota. Nine of the species were sequenced for 28S ribosomal DNA (rDNA). Two species were also examined using ITS rDNA sequences. One species was sequenced for a portion of CO1 mitochondrial DNA as well. Morphology for all nine species was reported along with one additional species identified through morphology alone.

The second study identified morphological and genetic variation of 28S rDNA of Neopsilotrema lisitsynae from North American waterfowl along with an analysis ofultrastructure using scanning electron microscopy. This was the first report of N. lisitsynae in North America, along with identification in four new hosts. Morphometrics of North American worms were found to vary highly in comparison to the original description from Ukraine-collected worms. Additionally, three features of Neopsilotrema were shown inaccurate in some cases: tegumental spines may be absent, egg number may be greater than 5, and the ovary may be located in a dextral, sinistral or medial position relative to the body. One variable nucleotide site was identified as well.

The final study identified a new species Neopsilotrema itascae from lesser scaup using identical methods as the N. lisitsynae study. Psilotrema mediopora was also reclassified based upon morphology into Neopsilotrema.All three studies reported expansions of currently described morphometrics and diagnostic genetic sequences which may be used for future work involving species diagnosis.


Robert Sorensen

Committee Member

Timothy Secott

Committee Member

David Sharlin

Date of Degree




Document Type



Master of Science (MS)


Biological Sciences


Science, Engineering and Technology



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