The taxonomy of myxosporeans was traditionally dependent solely upon the spore morphological and morphometric data. Intensive reports of intraspecific morphological variation, however, are increasingly challenging the taxonomic approaches for myxosporeans. In the present work, the morphological pleomorphism of myxospores of Myxobolus drjagini (Akhmerov, 1954) was observed. More interestingly, all of these pleomorphic myxospores occurred in the same plasmodium of M. drjagini, which refutes the previous hypothesis that morphological variation of M. drjagini was derived from its responses to differences in nutrition and immunological responses associated with different host tissues. Bearing the intraspecific morphometric and morphotype variation in mind, the combination of morphological, ecological and molecular data should be applied to the species identification and delimitation for myxosporeans. This is the first reported myxobolid species with high pleomorphic myxospores which are present in the same plasmodium.

Corresponding author

Key Laboratory of Healthy Freshwater Aquaculture Ministry of Agriculture and Rural Affairs and Key Laboratory of Fish Health and Nutrition of Zhejiang Province Zhejiang Institute of Freshwater Fisheries Huzhou Zhejiang Province China

Laboratory for Marine Biology and Biotechnology Pilot National Laboratory for Marine Science and Technology Qingdao Shandong Province China

School of Marine Science and Engineering Qingdao Agricultural University Qingdao Shandong Province China

State Key Laboratory of Freshwater Ecology and Biotechnology and Key Laboratory of Aquaculture Disease Control Institute of Hydrobiology Chinese Academy of Sciences Wuhan Hubei Province China

These authors contributed equally to this work

See more in PubMed

Akhmerov A.K. 1954: [On closely related species of a new myxosporean genus.] Dokl. Akad. Nauk. SSSR 97: 1101-1103. (In Russian.)

Atkinson S.D., Bartošová-Sojková P., Whipps C.M., Bartholomew J.L. 2015: Approaches for characterising myxozoan species. In: B. Okamura, A. Gruhl, J.L. Bartholomew (Eds.), Myxozoan Evolution, Ecology and Development. Springer, Cham, pp. 111-123. DOI

Barta J.R., Martin D.S., Liberator P.A., Dshkevicz M., Anderson J.W., Feigner S.D., Elbrecht A., Perkins-Barrow A., Jenkins M.C., Danforth H.D., Ruff M.D., Profous-Juchelka H. 1997: Phylogenetic relationships among eight Eimeria species infecting domestic fowl inferred using complete small subunit ribosomal DNA sequences. J. Parasitol. 83: 262-271. PubMed DOI

Chen Q.L., Ma C.L. 1998: Myxozoa: Myxosporea. Science Press, Bejing, 993 pp.

El-Mansy A., Molnár K. 1997: Extrapiscine development of Myxobolus drjagini Akhmerov, 1954 (Myxosporea: Myxobolidae) in oligochaete alternative hosts. Acta Vet. Hung. 45: 427-438. PubMed

Guo Q.X., Huang M.J., Liu Y., Zhang X.P., Gu Z.M. 2018: Morphological plasticity in Myxobolus Bütschli, 1882: a taxonomic dilemma case and renaming of a parasite species of the common carp. Parasit. Vectors 11: 399. PubMed DOI

Heiniger H., Cribb T.H., Adlard R.D. 2013: Intra-specific variation of Kudoa spp. (Myxosporea: Multivalvulida) from apogonid fishes (Perciformes), including the description of two new species, K. cheilodipteri n. sp. and K. cookii n. sp., from Australian waters. Syst. Parasitol. 84: 193-215. PubMed DOI

Liu Y., Gu Z.M., Luo Y.L. 2010: Some additional data to the occurrence, morphology and validity of Myxobolus turpisrotundus Zhang, 2009 (Myxozoa: Myxosporea). Parasitol. Res. 107: 67-73. DOI

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

Molnár K. 1971: Protozoan diseases of the fry of herbivorous fishes. Acta Vet. Hung. 21: 1-14.

Molnár K. 1994: Comments on the host, organ and tissue specificity of fish myxosporeans and types of their intrapiscine development. Parasitol. Hung. 27: 5-20.

Okamura B., Hartigan A., Naldoni J. 2018: Extensive uncharted biodiversity: the parasite dimension. Integr. Comp. Biol. 58: 1132-1145. PubMed DOI

Sakai H., Kawai T., Zhang J.Y., Sato H. 2019: New host records of three Kudoa spp. (K. yasunagai, K. thalassomi, and K. igami) with notable variation in the number of shell valves and polar capsules in spores. Parasitol. Res. 118: 143-157. PubMed DOI

Wu B.H., Wang S.X., Chen Y.S., Lu C.C., Huang L.F. 1979: [On the pathogenic agent of the twist disease of the silver carp in Hangzhou region of Zhejinang Province.] Acta Zool. Sin. 25: 50-57. (In Chinese with English abstract)

Wu B.H., Zhang Z.H., Zhang J., Chen Y.S., Huang L.F. 1975: [Twist disease of Hypophthalmichthys molitrix in Hangzhou region of Zhejinang Province.] Acta Zool. Sin. 21: 190-196. (In Chinese with English abstract.)

Xi B.W., Zhao X., Li P., Xie J. 2019: Morphological variation in Myxobolus drjagini (Akhmerov, 1954) from silver carp and description of Myxobolus paratypicus n. sp. (Cnidaria: Myxozoa). Parasitol. Res. 118: 2149-2157. DOI

Zhai Y.H., Whipps C.M., Gu Z.M., Guo Q.X., Wu Z.Z., Wang H.M., Liu Y. 2016: Intraspecific morphometric variation in myxosporeans. Folia Parasitol. 63: 033. DOI

Zhang B., Zhai Y.H., Gu Z.M., Liu Y. 2018: Morphological, histological and molecular characterization of Myxobolus kingchowensis and Thelohanellus cf. sinensis infecting gibel carp Carassius auratus gibelio (Bloch, 1782). Acta Parasitol. 63: 221-231. PubMed DOI