Myxobolus jialingensis n. sp. (Myxozoa: Myxobolidae) infecting urinary bladder and hepatopancreas of yellowhead catfish Tachysurus fulvidraco from China.

Abstract

In the present study, we described a novel myxosporean species, Myxobolus jialingensis n. sp. (Myxozoa: Myxobolidae), which infected the urinary bladder and hepatopancreas of yellowhead catfish Tachysurus fulvidraco in China. The mature spores of M. jialingensis n. sp. were pyriform with the length of 15.8 ± 0.7 (15.4-17.0) μm and width of 8.0 ± 0.3 (7.8-8.9) μm. Two pyriform polar capsules were slightly unequal in size: the larger polar capsule was 7.4 ± 0.3 (6.7-8.0) μm in length and 3.1 ± 0.2 (2.8-3.6) μm in width; and the smaller polar capsule measured 7.3 ± 0.3 (6.6-8.1) μm in length and 3.3 ± 0.2 (2.9-3.6) μm in width. The polar capsules were directed toward the apex of the spore, packing seven to eight spirals of the polar filaments. The small subunit ribosomal RNA gene (18S rDNA) sequence of M. jialingensis n. sp. was unique among all myxozoans, and the highest similarity was 96.1% with M. voremkhai. Phylogenetic analysis based on 18S rDNA sequences revealed that myxosporeans infecting the close host affinity (belonging to the same order) had close phylogenetic relationship and, some myxosporeans infecting the same host order might have multiple origins.