Answer to the Parasite Case of the Week 676: Cestode, most likely Diphyllobothrium/Dibothriocephalus/Adenocephalus species. The CDC DPDx webpage on diphyllobothriasis explains how some of the names have changed for this group of tapeworms.
Unfortunately the specimen was not submitted to the laboratory and we therefore can’t fully examine it. However, central uterine structure seen in the photo below is consistent with an adult tapeworm of the family Diphyllobothriidae:
Thanks again to Dr. Showler for contributing this case!