Myxobolus chushi n. sp. (Myxozoa:Myxosporea) parasitizing Schizothorax niger (Heckel), a native cyprinid fish from Wullar Lake in Kashmir Himalayas

Abstract In the study, a new species, Myxobolus chushi n. sp. infecting gills of wild specimens of Schizothorax niger (Heckel) inhabiting Wullar Lake in Kashmir Himalayas, (J&K) India has been described based on morphology of the myxospore and using partial 18S rDNA sequencing. Pathological changes in the gills have been studied with the help of histological sections stained with Luna's method. Twenty fish specimens were examined, out of which four had oval, white plasmodia in gills measuring 2.0 × 0.5 mm. The myxospores were spherical to ovoidal in shape with slightly attenuated posterior end, measuring 11.17 ± 0.23 (10.60–11.40) μm in length and 9.14 ± 0.06 (8.80–9.20) μm in width, having a prominent pore at the anterior end. The polar capsules were pyriform in shape, measuring 4.25 ± 0.15 (4.00–4.40) μm in length and 2.38 ± 0.27 (2.00–2.65) μm in width having polar filaments forming coils up to 5 in number. Parietal folds 9 in number present on the posterior part of the shell. The intensity of infection was recorded to be moderate as indicated by gill plasmodial index (GPI = 2). The plasmodium was located in the vascular network occupying whole of the gill lamella therefore typed as intralamellar vascular type, LV3 . Analysis of 18S small subunit (SSU) rDNA sequence of the isolate demonstrated 90% homogeneity with M. sp. KLT-2014 infecting scales of Labeo rohita from Myanmar and 89% with M. dermiscalis infecting scales of Labeo rohita from India.