Redescription and molecular analysis of Myxobolus shantungensis Hu, 1965 (Myxozoa: Myxosporea) infecting common carp Cyprinus carpio haematopterus.

Myxobolus shantungensis Hu, 1965 infects gill arches of common carp Cyprinus carpio haematopterus (Temminck and Schlegel), causing serious pathological effects on host fish. An inadequate original description and absence of molecular data make accurate early diagnosis challenging. To augment the original description, M. shantungensis is redescribed here using morphological and molecular biological methods. Mature spores of M. shantungensis were ellipsoidal or apple shaped in frontal view and lemon shaped in lateral view, averaging 8.2  ±  0.3 μm (8.0-9.0 μm) ×  10.1 ±  0.5 μm (9.2-11.1 μm)  ×  6.9  ±  0.3 μm (6.0-7.4 μm). Some spores had three to four "V"-shaped valve edge markings on the posterior of the spore. The two equal polar capsules were oval, measuring 4.3  ±  0.3 μm (3.8-5.0 μm)  ×  3.2  ±  0.2 μm (2.8-3.5 μm), situated at the anterior extremity of the spore. Polar filaments coiled with six to seven turns. Scanning electron microscopy revealed that the surface of mature spores of M. shantungensis was generally pitted with a number of irregular ridges in shape. M. shantungensis is also characterized on the molecular level using the sequence of the small subunit ribosomal RNA gene. A BLAST search revealed that this sequence did not match any available sequences in GenBank.