Morphological and molecular characterization of a new species Myxobolus gutturocola n. sp. (Myxozoa: Myxobolidae) from the throat of Hypophthalmichthys molitrix in China.

Myxobolus gutturocola n. sp. was isolated from the throat of silver carp, Hypophthalmichthys molitrix, in Chongqing, China. Myxospore valves are unsymmetrical and smooth. Mature spores are ellipsoidal in frontal view, measuring 12.5 ± 0.2 μm (n = 25) in length, 8.4 ± 0.2 μm (n = 25) in width and 7.1 ± 0.2 μm (n = 25) in thickness. Each spore has two pyriform and unequal sizes polar capsules, the large one with 5.7 ± 0.2 μm in length × 3.6 ± 0.2 μm in width and the small one with 4.6 ± 0.2 μm in length × 2.6 ± 0.1 μm in width. Polar filaments are coiled seven or eight turns in the large polar capsule and four or five turns in the small polar capsule. The coils are arranged almost perpendicularly to the longitudinal axis of the polar capsule. Morphological analysis revealed that M. gutturocola n. sp. is distinct from related species of Myxobolus Bütschli, 1882. Molecular analysis has demonstrated that its SSU rDNA sequences do not match with any available sequences in GenBank. Phylogenetic analysis of the SSU rDNA sequences indicated this species clustered in a clade composed exclusively of parasites infecting the fishes of the Leucisini lineage and most closely related to Myxobolus pavlovskii isolated from the gill filaments of silver carp in Hungary.