Abstract: Myxobolus yueyangensis sp. nov. parasitic in the intestine muscularis of common carp Cyprinus carpio with the form of round or ellipsoidal plasmodia, was found during a survey on fish myxozan diversity in Yueyang (29°37′N, 113°09′E). Mature spores were suborbicular in frontal view, and fusiform in back view, measuring 9.8±0.6 (9.6—10) μm long, 8.2±0.3 (8.0—8.5) μm wide, and 7.3±0.1 (7.0—7.5) μm thick. The surface of spores was smooth, and a round iodinophilous vacuole was found in its uniform protoplasm. Two Polar capsules were pyriform with an apophysis at its top and end closed to apex of spore, measuring 4.4±0.4 (3.8—5.1) μm in length, 2.7±0.2 (2.2—3.2) μm in width. Polar filaments coiled 4 to 5 turns.M. yueyangensis is morphologically distinct from all other Myxobolus species. The BLAST search indicated that the newly obtained small subunit ribosomal RNA (ssrRNA) gene sequence did not match any available sequences in GenBank, and showed the high similarity with Myxobolus yueyangensis of 96%. In the phylogenetical tree, M. yueyangensis was closely clustered with Myxobolus yueyangensis. Based on the comparison and analysis of spore morphology, host specificity, tissue or organ parasitized specificity, and 18S rDNA sequence, the myxosporean from the intestine of C. carpio described in the study should be a new species of genus Myxobolus.