DAO prepress abstract  -  doi: 10.3354/dao01912

ABSTRACT: During a necropsy investigation of a mortality event occurring at a turtle farm in Assumption Parish, Louisiana, spores of a myxozoan were identified in the renal tubules in 3 of 6, the gall bladder lumen of 2 of 6 and the bile ductule of 1 of 6 red eared slider turtles, Trachemys scripta elegans. In total myxozoa were identified in 4 of 6 turtles. In one turtle renal tubules contained numerous mature spores, had epithelial hyperplasia, granulomatous transformation, compression of adjacent tubules and interstitial lymphocytic nephritis. The genus of myxozoan was Myxidium based on spore morphology in cytological preparations, in histologic section, and by electron microscopy. In cytological preparation the spores had mean dimensions of 18.8 x 5.1 μm and a mean polar capsule dimension of 6.6 x 3.5 μm. Electron microscopy showed renal tubules contained plasmodia with disporoblasts with spores in various stages of maturation. Ultrastructure of mature spores demonstrated a capsule containing two asymmetrical overlapping valves and polar capsules containing a polar filament coiled 6 to 8 times and surrounded by a membrane composed of a double layer wall. The small subunit rDNA gene sequence was distinct from all other Myxidium species for which sequences are available. Additionally this is the first Myxidium species recovered from a North American chelonian to receive genetic analysis. Although T. s. elegans is listed as a host for Myxidium chelonarum, this newly described species of Myxidium possessed larger spores with tapered ends, and thus we described it as a new species, Myxidium scripta n. sp. This report documents a clinically significant nephropathy and genetic sequence from a Myxidium parasite affecting a fresh water turtle species in North America.