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Morphological and Molecular Characterisation of Myxidium kudoi Meglitsch, 1937 from the Blue Catfish Ictalurus furcatus, Valenciennes in Oklahoma, USA



Myxidium kudoi Meglitsch, 1937 has been described from the type host, blue catfish Ictalurus furcatus, with no additional host records or molecular data available for this species.


To provide molecular data and a novel host locality for this species and carry out phylogenetic analyses to infer the evolutionary relationship of the species to other members of the family Myxidiidae for which DNA sequence data is available.


These data were collected using myxospores from the gallbladder of a blue catfish, Ictalurus furcatus collected from Lake Texoma, Oklahoma, USA. Myxospores were morphologically consistent with the only other account of this species and not any other Myxidium species described from siluriform fishes.


Myxospores were oblong with rounded ends and were 10.8–12.6 (11.6 ± 0.5) µm in length and 4.7–6.6 (5.7 ± 0.5) µm in width. Polar capsules were subspherical and 2.7–3.9 (3.4 ± 0.3) µm in length and 2.4–3.5 (3.1 ± 0.3) µm in diameter, with each capsule containing a polar filament with 3–4 coils. Molecular data consisted of a 2918-bp sequence of the partial 18S, complete ITS1, 5.8S, ITS2, and partial 28S ribosomal rRNA regions as well as a 2455-bp sequence of partial 28S ribosomal RNA. The partial 18S and 28S data was used in a concatenated Bayesian phylogenetic analysis to further infer the evolutionary relationships of the Myxidiidae. Additionally, the partial 18S data was used in a separate phylogenetic analysis.


The present work reports novel morphological and molecular data for Myxidium kudoi as well as a novel locality of occurrence for this species. In concatenated phylogenetic analysis using 18S and 28S data and other molecular data from Myxozoa, M. kudoi grouped with other freshwater Myxidiidae. In the single-locus, 18S analysis, M. kudoi grouped with Myxidium rhodei from Rutilus rutilus and Myxidium amazonense from Corydoras melini, the only other Myxidium species of catfish for which molecular data are available.

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A Scientific Collecting Permit was issued to CTM by the Oklahoma Department of Wildlife Conservation (ODWC). CTM thanks the following for assistance in collecting at Lake Texoma: Matt Mauck, David Routledge, and Cliff Sager (ODWC, Caddo, OK, USA) as well as Dr. Don Cloutman (Burdett, KS, USA) for mentoring him on fish myxozoans. The authors acknowledge Wes Baumgartner of Mississippi State University’s College of Veterinary Medicine for histological examination of host tissue samples. This work was supported by the Department of Basic Sciences at Mississippi State University’s College of Veterinary Medicine.

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CTM received and identified the fish host, necropsied the host for parasite collection, and collected and fixed myxospores and infected host tissues. TGR prepared wet mounts of fixed spores, captured photomicrographs, produced plate images, and produced line drawings. ETW measured spores, designed primers used in the present study, carried out DNA extraction and molecular characterisation, compiled relevant literature, and made morphological comparisons with previously described species. TGR and ETW carried out phylogenetic analyses.

Corresponding author

Correspondence to Ethan T. Woodyard.

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On behalf of all authors, the corresponding author declares that the authors have no conflict of interest affecting this study.

Ethical standards

The fish collected for this study was collected under Oklahoma Department of Wildlife Conservation permit #1551646, issued to CTM. All relevant institutional policies for the ethical use of research animals were followed in handling and processing the fish.

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Woodyard, E.T., Rosser, T.G. & McAllister, C.T. Morphological and Molecular Characterisation of Myxidium kudoi Meglitsch, 1937 from the Blue Catfish Ictalurus furcatus, Valenciennes in Oklahoma, USA. Acta Parasit. 65, 388–395 (2020).

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  • Myxidium kudoi
  • Blue catfish
  • Ictalurus furcatus
  • Myxozoan
  • Myxidiidae