Host-parasite relationship of Ortholinea lauquen sp. nov. (Cnidaria: Myxozoa) and the fish Galaxias maculatus in northwestern Patagonia, Argentina

WAICHEIM, MA; ALAMA-BERMEJO, G; FLORES, VR; ALAMA-BERMEJO, G; FLORES, VR; VIOZZI, GP; ATKINSON, SD; VIOZZI, GP; ATKINSON, SD; WAICHEIM, MA

DISEASES OF AQUATIC ORGANISMS

INTER-RESEARCH

Lugar: Oldendorf/Luhe; Año: 2019 vol. 136 p. 163 - 174

0177-5103

ABSTRACT: Galaxias maculatus (Jenyns, 1842) is a widespread freshwater fish and an importantcomponent of the economically important whitebait fisheries across the Southern Hemisphere. Wereport a new myxosporean parasite (Cnidaria: Myxozoa) infecting the kidney of G. maculatusfrom northwestern Patagonia (Argentina). Ortholinea lauquen sp. nov. was characterized usingmyxospore morphology, morphometrics and small subunit rDNA (ssrDNA) sequence data. OurssrDNA phylogenetic analyses showed that O. lauquen sp. nov. is a member of theoligochaete−freshwater urinary tract clade and basal to a clade containing 4 different spore morphotypes(Chloromyxum, Myxidium, Zschokkella, Hoferellus). We explored host−parasite relationshipsat the macro- and microscale by analyzing the distribution, tissue tropism and pathologyof O. lauquen sp. nov. Prevalence was relatively low (7%) by microscopy, but PCR detectionrevealed hidden levels of infection (49%), with the highest detection in lakes Morenito andMoreno (63−90%, Río Negro Province). The only locality negative by both microscopy and PCRwas the Caleufu River (Neuquén Province), suggesting differences in fish life history traits (landlockedvs. potamodromous) or preference of the putative obligate invertebrate host for lentic habitats.O. lauquen sp. nov. sporulates in the renal tubules and occasionally in the glomerular space.The plasmodia frequently occluded the tubule lumina, and cellular necrosis and disintegration ofthe epithelium were observed. O. lauquen sp. nov. could represent a potential threat to G. maculatusculture under intensive farming conditions.