Occurrence of two myxosporean species, Myxobolus hakyi sp. n. and Hoferellus pulvinatus sp. n., in Pangasianodon hypophthalmus fry imported from Thailand to Europe as ornamental fish

Abstract

Fingerlings of the sutchi catfish Pangasianodon hypophthalmus, a favorite food fish in South Asia, is regularly imported by European fish traders and sold in pet fish shops. In shipments from Thailand, a skin and a kidney infection of this fish caused by myxosporean parasites was found both in Hungary and Russia. In the skin of the fish, small millet-sized nodules containing great numbers of a Myxobolus species were found, while in the renal glomeruli, spores and sporogonic stages of a Hoferellus species developed. The skin-infecting species described as Myxobolus hakyi sp. n. had 15.9 x 6.6-microm-sized spores with elongated polar capsules, while the renal species described as Hoferellus pulvinatus sp. n. had roundish spores with a size of 6.5 x 5.0 microm and had a characteristic pillow-like structure at its posterior end. Besides morphology, histology of infection and 18S rDNA sequences were studied.

Supplemental description and molecular characterization of Myxobolus miyarii Kudo, 1919 (Myxosporea: Myxobolidae) infecting intestine of Amur catfish (Silurus asotus)

“…M. kawabatae is different from M. miyairii by the larger spores and longer polar capsules. Besides the above species found in China, M. hakyi, a recently named sutchi catfishinfecting species found in Thailand is also morphologically similar with M. hiyairii (Baska et al 2009). But the larger spore, less turns of polar filament and infection site can differentiate them (Table 2).…”

Myxobolus marajoensis sp. n. (Myxosporea: Myxobolidae), parasite of the freshwater catfish Rhamdia quelen from the Brazilian Amazon region

“…The morphology of this species is similar to that of M. miyarii (LIU et al, 2016) and M. cunhai (PENIDO, 1927), given the pyriform shape of the spores, which are distinct from the ovoid spores of M. pangasii (MOLNÁR et al, 2006), the elliptical spores of M. hakyi Baska et al (2009) and M. gayerae Molnár et al (2007), and the spherical spores of M. bivacuolatus (NARASIMHAMURTI & KALAVATI, 1986) (Table 1).…”

“…A number of other Myxobolus species found in siluriforms have been described based on the analysis of the 18S rDNA gene, including M. myarii, found in the S. asotus by Liu et al (2016). Using this gene, Baska et al (2009) confirmed the presence of M. hakyi in the epidermis of the P. hypophthalmus, while Molnár et al (2006) found M. pangasii infecting its spleen.…”

“…In comparison with the Myxobolus species found in the intestinal tracts of other catfish species, Myxobolus marajoensis sp. n. is closest in size to M. cunhai, which infects the catfish P. clarias maculatus (PENIDO, 1927), M. bivacuolatus and M. pangasii, found in Pangasius hypophthalmus (MOLNÁR et al, 2006;BASKA et al, 2009), and M. miyarii, a parasite of S. asotus (LIU et al, 2016) (Table 1). Myxobolus marajoensis sp.…”

“…In the catfish (Siluriformes), these parasites have been found infecting a variety of organs, such as the gills of the bandit corydoras, Corydoras melini Lönnberg andRendahl, 1930 (MATHEWS et al, 2016) and the jau, Zungaro jahu Ihering, 1898 (ADRIANO et al, 2009), the intestine of the Amur catfish Silurus asotus Linnaeus, 1758(LIU et al, 2016 and the Philippine catfish Clarias batrachus Linnaeus, 1758(NARASIMHAMURTI & KALAVATI, 1986, the intestine and gills of the European chub, Leuciscus cephalus Linnaeus, 1758 (MOLNÁR et al, 2007) and the spleen of the striped catfish, Pangasianodon hypophthalmus Sauvage, 1878 (BASKA et al, 2009). …”