Seasonal Variation in Relative Infection Intensity of Larvae of the Salamander Desmognathus amphileucus (Caudata: Plethodontidae) by the Trematode Metagonimoides oregonensis (Digenea: Heterophyidae)

The trematode currently recognized as Metagonimoides oregonesis primarily utilizes the Southern Black-bellied Salamander, Desmognathus amphileucus, as a second intermediate host in southern Appalachian streams. We investigated seasonal variation in relative intensity within larvae of this salamander species in the Broad River system of northeastern Georgia by counting metacercariae visible through the ventral body wall in February, May, August, and November of 2023. Summer hatching and metamorphosis by salamander larvae coupled with likely summer shedding time of trematode cercariae from the snail host explain much of the variation, which showed a peak relative intensity in November. However, this peak remained even after the effect of salamander size (and presumably age) had been removed. The seasonal pattern we observed may be subject to interannual variation.