Honors Program


Date of this Version

Spring 3-10-2022

Document Type



Chesley, E.K. 2022. Helminths from rodents in the Galapagos. Honors Undergraduate Thesis. University of Nebraska-Lincoln.


The new species of Raillietina cestode will be officially described in another publication.

Copyright Emma Chesley 2022.


In this first report of endoparasites from endemic mammals of the Galápagos islands, we identify a new species of cestode of the genus Raillietina (Cyclophyllidea: Davaineidae) from species of Nesoryzomys and summarize the extent of helminth parasitism in both Oryzomyine endemics and introduced species of Rattus. The Raillietina cestode was discovered in 1999 by Dowler and colleagues during a survey of the Galápagos. Surprisingly, no helminth parasites have been reported living in rodents of the Galápagos, and little work has yet been done describing Galápagos parasite diversity. There are also very few works in the literature describing the life history of both invasive and autochthonous rodents of the island group. Understanding the life history of the Galápagos biota and the origin of the Galápagos islands is important in understanding the evolution of the Galápagos fauna today. Through an extensive literature review, a summary of the parasite history of the seven endemic and three invasive rodent species was completed. There have been three distinct genera of native rodents on the islands, with species of Nesoryzomys and Aegialomys extant and Megaoryzomys now extinct. Human colonization brought three species of highly invasive and competitive rodents including Rattus rattus, R. norvegicus, and Mus musculus.