Redescription of two species of cystidicolid nematodes (Spirurina: Cystidicolidae) from Notopterus notopterus (Osteichthyes) in Thailand

Occurrence and First Molecular Characterization of Spinitectus notopteri Karve et Naik, 1951, Infected Bronze Featherback (Notopterus notopterus) in India

PURPOSE

The nematode genus Spinitectus Fourment, 1883, comprises species that are mainly parasitic on freshwater and marine fishes. However, our knowledge of the distribution and molecular identification of Spinitectus spp. in the Indian region is rather limited. This study aims to fill this gap in our knowledge using molecular data as evidence for Spinitectus species characterization.

METHODS

Bronze featherback were obtained opportunistically from the fish markets of district Muzaffarnagar (29.4727° N, 77.7085° E), Uttar Pradesh, India. Nematode species collected from the gastrointestinal tract were characterized morphologically and molecularly. Partial sequences of the ribosomal 18S rRNA gene were used for molecular characterization of the present specimens.

RESULTS

The current study represented molecular analysis that determined the presence of the species Spinitectus notopteri Karve et Naik, 1951. The sequences obtained were closely related to representatives of the family Rhabdochonidae.

CONCLUSION

This first molecular exploration of S. notopteri Karve et Naik, 1951, in the GenBank database and for any species of Spinitectus from India indicates a lack of genetic data for parasitic nematodes.

Description of myxosporeans (Cnidaria: Myxozoa) infecting the popular food fish Notopterus notopterus (Pisces: Notopteridae) in Malaysia and India

This study was a co-operative investigation of myxosporean infections of Notopterus notopterus, the bronze featherback, which is a popular food fish in the South Asian region. We examined fish from Lake Kenyir, Malaysia and the River Ganga, Hastinapur, Uttar Pradesh, India, and observed infections with two myxosporeans: Myxidium cf. notopterum (Myxidiidae) and Henneguya ganapatiae (Myxobolidae), respectively. These species were identified by myxospore morphology, morphometry and host tissue affinity, and the original descriptions supplemented with small-subunit ribosomal DNA sequences and phylogenetic analysis. Free myxospores of M. cf. notopterum were found in the gallbladder, and measured 14.7 ± 0.6 μm long and 6.3 ± 0.6 μm wide; host, tissue and myxospore dimensions overlapped with the type, but differed in morphological details (spore shape, valve cell ridges) and locality (Malaysia versus India). Plasmodia and spores of H. ganapatiae were observed in gills, and myxospores had a spore body 9.7 ± 0.4 μm long, 4.5 ± 0.5 μm wide; sample locality, host, tissue, spore morphology and morphometry matched the original description. Small-subunit ribosomal DNA sequences were deposited in GenBank (M. cf. notopterum MT365527, H. ganapatiae MT365528) and both differed by >7% from congeneric species. Although the pathogenicity and clinical manifestation of myxozoan in humans are poorly understood, consumption of raw fish meat with myxozoan infection was reported to be associated with diarrhea. Identification of current parasite fauna from N. notopterus is an essential first step in assessing pathogen risks to stocks of this important food fish.

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Two myxozoan species were identified in the important food fish Notopterus notopterus.

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Myxospores of Myxidium cf. notopterum and Henneguya ganapatiae were investigated.

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Although rare myxozoan species can be zoonotic M. cf. notopterum and H. ganapatiae are not known to infect humans.

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Country-specific myxozoan parasites were found in N. notopterus from India and Malaysia.

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DNA sequence data helped to clarify the taxa and improve identification.