Ortholinea auratae n. sp. (Myxozoa, Ortholineidae) infecting the urinary bladder of the gilthead seabream Spams aurata (Teleostei, Sparidae), in a Portuguese fish farm

摘要

A new myxosporean species, Ortholinea auratae n. sp., is described from the gilthead seabream, Spams aurata Linnaeus, 1758 (Teleostei, Sparidae) from a fish farm in Algarve, Portugal. Plasmodia and spores were found in the urinary bladder and, less frequently, in the posterior kidney. Plasmodia were polymorphic, presenting an irregular cellular membrane due to the presence of several peripheral projections, which in turn were covered by a glycocalyx-like sheet. Mature spores were subspherical in valvular view and ellipsoidal in sutural view, measuring 9.0±0.3 (8.2-10.1) urn in length, 8.3±0.4 (7.5-9.1) mum in width, and 7.2±0.5 (6.3-8.4) urn in thickness. The two valves comprising the spores displayed an intricate pattern of surface ridges and were also enveloped by a glycocalyx-like sheet. Two subspherical polar capsules, 3.2±0.1 (2.9-3.6) urn long and 2.7±0.1 (2.4-2.9) urn wide, were located at the anterior pole and displayed divergent orientation. The polar filament coiled in three to four turns. The comprehensive analysis of the parasite's ultra-structural observations and molecular data for the small sub-unit (SSU) ribosomal DNA (rDNA) gene identify O. auratae n. sp. as a new species, clustering together with other myxosporeans infecting the excretory system to form a subclade of the main freshwater clade.