Initial Description of Dermocystid Infections in Silvery Salamanders (Ambystoma Platineum) from Vermilion County, Illinois

Emerging infectious diseases such as ranaviruses, chytridiomycosis, and Ribeiroia sp. can pose a significant risk to threatened and endangered amphibian species, but much is unknown about the ecology and epidemiology of other amphibian infectious diseases. Mesomycetozoan parasites in the order Dermocystida have been reported to encyst in the skin of European amphibians for over 100 years. Reports of these infections are sporadic, and while higher rates of infection have been documented in declining populations, the contribution of parasitism to the declines is unknown. Recently, Dermocystid parasites were described for the first time in Eastern red-spotted newts (Notophthalmus viridescens) from the Northeastern United States. Visibly-infected newts from a population observed in captivity experienced higher mortality rates than uninfected conspecifics. The current impacts of Dermocystid parasite infections on free-living amphibian populations are unknown, but their recent emergence in the US is concerning and information on natural infections is important to determine their potential impact on species of conservation concern. Silvery salamanders (Ambystoma platineum) are considered state-endangered in Illinois. Beginning in 2017, raised white skin nodules were observed in 19 adult salamanders during routine health surveillance at four ponds from two geographically separated study sites. These nodules were confirmed to be a Dermocystid organism via histopathology and 18S sequencing. This presentation will characterize the gross and histologic appearance of this organism, describe its distribution in Vermilion County, Illinois, and review its molecular classification and phylogeny. This is the first report of a Dermocystid infection west of Indiana, and is only the third North American species in which infection has been documented. Longitudinal assessment of the affected populations in the upcoming years will help determine the effects of Dermocystid parasitic infections in a state-endangered urodele.