Myxobolus okamurae sp. nov. (Myxosporea: Myxozoa) causing severe gill myxoboliosis in the cyprinid Labeo bata in a cold water wetland, Punjab (India).

During the present study on myxozoan parasites infecting gills of cyprinid carps inhabiting Ranjit Sagar Wetland, a new parasite, Myxobolus okamurae sp. nov. infecting gills of Labeo bata has been described based on morphology, histopathology and partial 18S rDNA sequencing. For M. okamurae sp. nov., hundred fish specimens were examined, out of which thirty-three had large cylindrical to round, white plasmodia in gills, each plasmodium measured 0.9-3.0 mm in diameter. The myxospore body was pyriform in shape, measuring 12.25 × 4.93 μm, with a small intercapsular process at the anterior end. The polar capsules were equal and pyriform in shape, measuring 6.06 × 1.45 μm having polar filaments forming coils up to 13-14 in number. The intensity of infection was recorded to be heavy as indicated by gill plasmodium index (GPI = 3). Sequence analysis showed that M. okamurae sp. nov. is 91% similar with M. catlae infecting gills of Catla catla from India followed by M. intimus infecting gills of Leuciscus idus from Hungary. The phylogenetic tree based on the final edited alignment (403 bp) with Maximum-Likelihood showed the high bootstrap value of 75 and formed two major clades involving M. okamurae sp. nov. with M. pendula M. catlae and M. dispar in one clade with a low bootstrap value of 23 and the rest of the species in a separate clade. The plasmodium was located in the gill lamella and typed as "intralamellar vascular type, LV3".

Pubmed ID: 29253599 RIS Download