Widespread infection of the Eastern red-spotted newt (Notophthalmus viridescens) by a new species of Amphibiocystidium, a genus of fungus-like mesomycetozoan parasites not previously reported in North America

Abstract

Given the worldwide decline of amphibian populations due to emerging infectious diseases, it is imperative that we identify and address the causative agents. Many of the pathogens recently implicated in amphibian mortality and morbidity have been fungal or members of a poorly understood group of fungus-like protists, the mesomycetozoans. One mesomycetozoan, Amphibiocystidium ranae, is known to infect several European amphibian species and was associated with a recent decline of frogs in Italy. Here we present the first report of an Amphibiocystidium sp. in a North American amphibian, the Eastern red-spotted newt (Notophthalmus viridescens), and characterize it as the new species A. viridescens in the order Dermocystida based on morphological, geographical and phylogenetic evidence. We also describe the widespread and seasonal distribution of this parasite in red-spotted newt populations and provide evidence of mortality due to infection.

What Drives Chytrid Infections in Newt Populations? Associations with Substrate, Temperature, and Shade

“…None of the newts sampled from these ponds showed overt signs of chytridiomycosis, such as unusual skin sloughing or lethargy (Voyles et al, 2009). Indeed, most of the newts appeared visibly healthy aside from occasional infection by other more visible parasites (Raffel, 2006;Raffel et al, 2006aRaffel et al, , 2008. There were two significant univariate predictors of Bd load in the within-population analysis (Table 1): SVlength 2 (coefficient [coef.]…”

Pathological and phylogenetic characterization ofAmphibiothecumsp. infection in an isolated amphibian (Lissotriton helveticus) population on the island of Rum (Scotland)

“…In addition to direct skin exposure, the possibility of oral transmission cannot 455 be ruled out due to the microscopic observation of parasite cysts within the digestive system. This 456 might also explain the presence of liver cysts, which could pass through the bile duct following 457 ingestion as hypothesised previously (Raffel et al, 2008). However, due to the anatomical location 458 of the liver, it is possible that parasite spores migrate through the sub-adjacent dermal-muscle layers 459 and into the liver.…”

Rhinosporidiosis in African reed frogs Hyperolius spp. caused by a new species of Rhinosporidium

“…Similar details have been published for Amphibiocystidium spp. (Dermocystida), a known pathogen of frogs , Raffel et al 2008. However, the comparison of morphological details, especially the size of sporangia and microspores, eventually resulted in affiliation to the genus Rhinosporidium (Kennedy et al 1995).…”

“…In general, infections cause small multifocal nodules or pustules, but species assignment of pathogens based on external symptoms and spore morphology seems ambiguous without additional evidence from rDNA sequence analyses (Fredricks et al 2000, Feldman et al 2005, Densmore & Green 2007. Dermocystid infections are usually not fatal, but may reduce survival rate in captive newts (Raffel et al 2008) or indirectly cause increased mortality by facilitating co-infection with Bd in Rana lessonae (Pascolini et al 2003, Di Rosa et al 2007). Presence of presumptive Amphibiocystidium cysts in the frog Hysiboas pulchellus in Uruguay did not affect behavior and condition of the hosts and dead or moribund frogs were never observed (Borteiro et al 2014 …”

“…Amphibiocystidium ranae infects some European frog and newt species producing nodular-type, externally visible skin lesions (Broz & Privora 1952, Pascolini et al 2003, González-Hernández et al 2010, Courtois et al 2013. Recently, another Amphibiocystidium species (A. viridescens) has been found infecting North American newts (Raffel et al 2008). Dermocystid infections are thought not to be fatal, but self-limiting (Densmore & Green 2007).…”