MYXOBOLUS BARAKENSIS SP. N. AND ONE KNOWN SPECIES OF HENNEGUYA (CNIDARIA : MYXOSPOREA) FROM THE FRESHWATER FISHES OF BARAK VALLEY, ASSAM K. Lebanan* and N. Mohilal Department of Life Sciences, Manipur University, Canchipur - 795 003, India. *e-mail: lebanank@manipuruniv.ac.in, nmohilal@manipuruniv.ac.in (Received 22 February 2021, Revised 14 April 2021, Accepted 29 April 2021) ABSTRACT : M. barakensis sp. n. (Cnidaria : Myxosporea : Bivalvulida) had been described from gills and ovary of the freshwater garfish, Xenentodon cancila based on morphological data. Ovoid to spherical cyst-like plasmodia were found in the ovary only. No pathological changes were observed in the host tissue surrounding the cyst-like plasmodia. Mature myxospores were ovoid in frontal view and lenticular in lateral view, with slightly pointed anterior and rounded posterior ends. Myxobolus was a common parasite of freshwater fishes reported from almost all over the world. The severity of infection may lead to mortality of fish host. The present paper dealt with the description of a new species of Myxobolus sp. from the Xenentodon cancila, from Barak River, Assam, India. The plasmodia of Myxobolus barakensis sp.n. were found infecting gills and ovary of Xenentodon cancila, the freshwater garfish. The infection rate was found to be 36.67% (30 fishes were examined and 11 fishes were infected). Numerous minute plasmodia each filled with hundreds of spores were detected. Smear of mucous from gills exhibited hundreds of spores. The present species had been proposed as new on the basis of its peculiar shape and morphometric data. The report had been made as the first record of myxobolid infection in the freshwater garfish from Barak River, Assam (India). The plasmodia were not found in the gill filaments and were present within the entire length of the ovary. The present study also observed a known Henneguya species i.e. H. bleekeri from the gills and fins of the same host fish Mystus bleekeri from Barak Valley, Assam. The prevalence rate of infection was 31.81%. This was also the first record of Henneguya sp. in the freshwater fishes of Barak Valley, Assam. Key words : Myxozoa, parasite, freshwater gar fish, Assam. How to cite : K. Lebanan and N. Mohilal (2021) Myxobolus barakensis sp. n. and one known species of Henneguya (Cnidaria : Myxosporea) from the freshwater fishes of Barak Valley, Assam. J. Exp. Zool. India 24, 1267-1274. DocID: https:// connectjournals.com/03895.2021.24.1267 INTRODUCTION Myxosporeans (Cnidaria : Myxosporea) are common, diverse parasites of marine and freshwater fishes (Lom and Dykova, 2006). Myxozoans are microscopic parasitic cnidarians of fish (Okamura et al, 2015). They are a group of microscopic metazoans, which are primarily parasites of freshwater and marine fishes and a few other vertebrates (Sitja-Bobadilla et al, 2016). These parasites are characterized by multicellular myxospore, composed of 1 to 15 nematocyst-like polar capsules each containing a polar filament and one or many amoeboid sporoplasms (Kent et al, 2001; Whipps et al, 2003). The occurrence of myxozoan parasites has been extensively studied in aquaculture due to their pathogenic potential (Fiest and Longshaw, 2006). They will induce significant mortalities in wild and farmed fishes, resulting in major economic losses (Naldoni et al, 2009; Morsy et al, 2012 and Gomez et al, 2014). Among myxozoans, the category Myxosporea represents more than 2200 nominal myxosporean species that are classified into 64genera and 17 families, essentially supported morphological characteristics with some fragment data on their SSU rDNA sequence and also, within the myxosporea, Myxobolus has the foremost speciose compared to other genus of an equivalent Family: Myxobilidae with approximately 910 species belonging to the genus Myxobolus Bütschli, 1882 (Lom and Dykova, 2006). Xenentodon cancila Hamilton, 1822 (Beloniformes: J. Exp. Zool. India Vol. 24, No. 2, pp. 1267-1274, 2021 www.connectjournals.com/jez ISSN 0972-0030 DocID: https://connectjournals.com/03895.2021.24.1267 eISSN 0976-1780