Protistology 8 (2) 41–52 (2014) |
Molecular and morphometric characterization of Thelohanellus caudatus (Myxosporea: Myxobolidae) infecting the caudal fin of Labeo rohita (Hamilton) |
1 Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal,
India
Summary Thelohanellus caudatus infecting the caudal fin of carp Labeo rohita was characterized morphologically and by 18S rRNA gene sequence analysis. Infection of Myxobolus spp. and Thelohanelus spp. was more common in L. rohita gills with the parasitic frequency index of 66.67% and 50.00%, respectively. The prevalence of fin infecting Thelohanellus was 12.50%. The infection rate was low to moderate. The plasmodia on the caudal fin were small, white to pale yellow, elongated and 0.5–0.7 mm in length. The caudal fin of infected fish had up to 3 plasmodia, which contained about 50–60 spores each. Morphologically, Thelohanellus species closely resembled Thelohanellus caudatus. The comparison of 18S rRNA gene sequences of T. caudatus to other Thelohanellus spp. available in GenBank revealed only 72–78% homology. The T. caudatus (accession number KC865607) was clustered phylogenetically with the clade of freshwater myxosporeans. In the phylogenetic tree, T. caudatus formed dichotomy with T. hovorkai with low node support. This communication is the first report on molecular characterization of T. caudatus. Key words: aquaculture, Labeo rohita, Myxosporea, molecular characterization, phylogenetic relationship, Thelohanellus caudatus Address for correspondence: T. Jawahar Abraham. Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, No 5 - Budherhat Road, Chakgaria, Panchasayar P.O., Kolkata - 700 094, West Bengal, India; e-mail: abrahamtj1@gmail.com |
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