Endoparasites of (Serpentes: Viperidae), with a checklist in rattlesnakes.

The helminth and pentastomid fauna of 50 specimens of from the Yucatán Peninsula, Mexico is documented. The examination revealed the presence of three nematode species (, , and ), and one pentastomid (). The threee nematode species had the same prevalence (2%), while the pentastomid had a higher prevalence (8%). The pentastomid was the most abundant and intense parasite, although it was only found in four snake hosts. acts as definitive host for the adult helminths and pentastomids, with rodents as the probable intermediate hosts. This work represents the first systematic survey on the parasitic helminth and pentastomid fauna of , and includes four new geographical records. Additionally, a checklist of helminths and pentastomids reported for and is provided. To date, a total of 32 helminth and 7 pentastomid species have been recorded as parasites of rattlesnakes. Nematoda possessed the highest species richness. The genera with the highest number of host species were and , followed by . The rattlesnake species with the highest number of reported parasites was (18 nematodes and 2 pentastomids).