A new species Myxobolus guanqiaoensis was found in the liver and abdominal cavity of Allogynogenetic silver prassian carp at Guanqiao, in Oct, 1996. The type specimens were preserved in the Laboratory of Fish Diseases, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan, China. Myxobolus guanqiaoensis sp. nov. Host and site: Allogynogenetic silver crucian carp (Carassius auratus gibelio female X Cyprinus carpio male), Liver and abdominal cavity. Locality: Guanqiao, Wuhan, China. Infection rate: above 60%. Cyst: Oval or elliptic in form, white in color; 2.1-4.0 cm in diameter, embraced by a transparent membrane. Spores: Spores elongated-oval in thecal view. Pointed at anterior end and bluntly round in posterior end; 1-3 V-shaped folds at posterior end; elongated elliptic in sutural view; sutural line S-shaped and distinct; shell valves smooth; intercapsular appendix distinct Two polar capsules eggplant, unequal in size, polar capsule located at 1/2 position of spore length; 7-8mum flat coiled filament. Dimensions of 20 fresh spores: Length 19.6(18.2-22.0) mum. width 10.8(9.0-13.2) mum. thickness 8.3(8.0-9.0) mum, large polar capsules 9.5(8.8-10.1) by 3.7(3.0-4.4)mum, small polar capsules 8.4(7.9-9.8) by 3.6(3.2-4.0)mum. Polar capsule nuclei situated at the inner of two polar capsules. An indistinct iodinophilous vacuole and two round germinal nuclei. The shape of this new species is similar to Myxobolus gigi, Myxobolus koi and Myxobolus aureatus, but differs from them in dimensions of spore, the size of polar capsule, suture line and host.