Molecular and phylogenetic characterization of Thelohanellus qadrii (Myxozoa, Myxosporea, Bivalvulida) infecting the secondary gill epithelium of Indian major carp, Catla catla (Hamilton, 1822)

Document Type: Original article


1 Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Kolkata, India

2 Dept of Veterinary Microbiology, Faculty of Veterinary and Animal Sciences, WBUAFS, Kolkata

3 Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Kolkata, India


Myxosporean taxonomy which is traditionally based on the morphology of the myxospore stage, is in a state of flux given new insights provided by the expanding dataset of DNA sequences. To date, more than 40 species of Thelohanellus from India have been described according to morphometric characteristics. Nevertheless, molecular data on these histozoic myxosporean parasites of freshwater fish are scarce. In the present study, molecular characterizations of Thelohanellus qadrii infecting the secondary gill epithelium of Indian major carp Catla catla (Hamilton, 1822) and its phylogenetic relationship is reported. The sub-adult cultured catla were observed to have low to moderate gill myxosporean infections. The morphometry of mature spores was in compliance with original descriptions of T. qadrii. Based on the analysis of 18S rRNA gene, phylogenetic clusters which were established according to a consensus sequence, illustrated the taxonomic placement of a series of myxobolids. The DNA sequence homogeneity of T. qadrii (KF170928) with other Thelohanllus spp. ranged from 78% to 95% and formed a dichotomy with cyprinid gill lamellae infecting T. toyamai (HQ338729). Distance matrix results indicated a high genetic diversity among myxosporeans. The present report is the first on the molecular and phylogenetic characterizations of T. qadrii.


1. Lom J, Dyková I. Myxozoan genera: definition and notes on taxonomy, life-cycle terminology, and pathogenic species. Folia Parasitol 2006;53:1-36.

2. Basu S, Modak BK, Haldar DP. Synopsis of the Indian species of the genus Thelohanellus Kudo, 1933 along with the description of Thelohenellus disporomorphus sp. n. J Parasitol Appl Anim Biol 2006;15:81–94.

3. Molnár K, Marton S, Székely C, Eszterbauer E. Differentiation of Myxobolus spp. (Myxozoa: Myxobolidae) infecting roach (Rutilus rutilus) in Hungary. Parasitol Res 2010;107(5):1137-1150.

4. Liu Y, Whipps CM, Liu WS, Zeng LB, Gu ZM. Supplemental diagnosis of a myxozoan parasite from common carp Cyprinus carpio: Synonymy of Thelohanellus xinyangensis with Thelohanellus kitauei. Vet Parasitol 2011;178:355-359.

5. Singh R, Kaur H. Thelohanellus (Myxozoa: Myxosporea: Bivalvulida) infections in major carp fish from Punjab wetlands (India). Protistol 2012;7:178–188.

6. Yokoyama H, Grabner D, Shirakashi S. Transmission Biology of the Myxozoa. In: Health and Environment in Aquaculture. Carvalho ED, David GS, Silva RJ (eds), InTech, Croatia 2012; PP 1-42. ISBN: 978-953-51-0497-1, Available from transmission-biology-of-the-myxozoa (Accessed on 30 May, 2013).

7. Kent ML, Andree KB, Bartholomew JL,  El-Matbouli M, Desser SS, Devlin RH, Feist SW, Hedrick RP, Hoffmann RW, Khattra J, Hallett SL, Lester RJG, Longshaw M, Palenzeula O, Siddall ME, Xiao C. Recent advances in our knowledge of the Myxozoa. J Eukary Microbiol 2001;48:395–413.

8. Eszterbauer E. Genetic relationship among gill-infecting Myxobolus species (Myxosporea) of cyprinids: molecular evidence of importance of tissue-specificity. Dis Aquat Org 2004;58:35–40.

9. Fiala I. The phylogeny of Myxosporea (Myxozoa) based on small subunit ribosomal RNA gene analysis. Int J Parasitol 2006;36:1521-1534.

10. Cech G, Molnár K, Székely C. Molecular genetic studies on morphologically indistinguishable Myxobolus spp. infecting cyprinid fishes, with the description of three new species, M. alvarezae sp. nov., M. sitjae sp. nov. and M. eirasianus sp. nov. Acta Parasitol 2012;57:354-366.

11. Zhang JY, Gu ZM, Kalavati C, Eiras JC, Liu Y, Guo QY, Molnár K. Synopsis of the species of Thelohanellus Kudo, 1933 (Myxozoa: Myxosporea: Bivalvulida). Sys Parasitol 2013;86:235-256.

12. Mondal A, Banerjee S, Patra A, Adikesavalu H, Ramudu KR, Dash G, Joardar SN,  Abraham TJ. Molecular and morphometric characterization of Thelohanellus caudatus (Myxosporea: Myxobolidae) infecting the caudal fin of Labeo rohita (Hamilton). Protistol 2014;8:41-52.

13. Lom J, Arthur JR. A guideline for the preparation of species descriptions in Myxosporea. J Fish Dis 1989;12:151-156.

14. Barta JR, Martin DS, Liberator PA, Dashkevicz M, Anderson JW, Feighner SD, Elbrecht A, Perkins-Barrow A, Jenkins MC, Danforth HD, Ruff MD, Profous-Juchelka H. Phylogenetic relationships among eight Eimeria species infecting domestic fowl inferred using complete small subunit ribosomal DNA sequences. J Parasitol 1997;83:262-271.

15. Thompson JD, Gibson JJ, Plewniak F, Jeanmougin F, Higgins DG. The ClustalX windows interface: flexible strategies for multiple sequence alignment aided by quality analysis tools. Nucleic Acids Res 1997;24:4876–4882.

16. Tamura K, Peterson D, Peterson N, Stecher G, Nei M, Kumar S. MEGA5: Molecular evolutionary genetics analysis using maximum likelihood, evolutionary distance, and maximum parsimony methods. Mol Biol Evol 2011;28:2731-2739.

17. Kimura M. A Simple method for estimating evolutionary rate of base substitutions through comparative studies of nucleotide sequences. J Mol Evol 1980;16:111-120.

18. Felsenstein J. Phylogenies and the method. Am Nat 1985;125:1-15.

19. Lalithakumari PS. Studies on parasitic protozoa (Myxosporidia) of freshwater fishes ofAndhra Pradesh,India. Rivista di Parasitol 1969;30:154-225.