Myxobolus chakravartyi Haldar et al. (1983)

Sz, Csaba, ekely, Ghosh, Subarna, Borz, eka, ak, Goswami, Urvashi, alm, Moln, an, ar & Cech, abor, 2021, The occurrence of known Myxobolus and Thelohanellus species (Myxozoa, Myxosporea) from Indian major carps with the description of Myxobolus bandyopadhyayi n. sp. in West Bengal, International Journal for Parasitology: Parasites and Wildlife 16, pp. 18-25 : 22-23

3.4. Myxobolus chakravartyi Haldar et al. (1983) ( Figs. 11–13 )

Four out of the 9 catla specimens purchased on the fish market were infected with small ellipsoidal-shaped plasmodia reaching a size of 200–300 in length and 150–200 in width and attaching to the cartilaginous fin rays ( Fig. 11 ). The plasmodia contained 2,000 to 8,000 spores.

Spores ( Figs. 12 and 13 ) medium sized, roundish or short ellipsoidal in frontal view and lemon shaped in sutural view having a small conical, 0.5–1 long protuberance at the anterior end. Spores 12 ± 0.38 (11.6–12.6) long, 10 ± 0.45 (9.4–10.7) wide and 6 ± 0.36 (4–6.2) thick. Two polar capsules short pyriform, different in size. The larger 5.7 ± 0.36 (5.4–6.2) long and 4.1 ± 0.61 (3.5–5) wide, the smaller 3.6 ± 0.15 (3.5–3.8) long and 2.2 ± 0.1 (2.1–2.3) wide. Polar tubules not seen. Spore with a large, triangular, eccentrically located intercapsular appendix. Sporoplasm nuclei indiscernible. A small iodinophilous vacuole found in the sporoplasm. Mucous envelope not found. The thickness of the spore wall (which corresponds to the emerging collar of the suture) 1 ± 0.16 (0.8–1.2). Some crippled spores ( Fig. 12 inset) bear Henneguya like tails of 4–5.

Host: Catla Gibelion catla (Hamilton)

Locality: Kakinara, Bhatpara market (22.51 ◦ N 88.23 ◦ E), on the Kalyani expressway.

Site of infection: fins.

Prevalence of infection: 4 specimens from 9 fish.

Type material: Photo-types and histological preparations were deposited in the parasitological collection of the Zoological Department, Hungarian Natural History Museum, Budapest, Coll. No. HNHM-PAR-72080. The ssrDNA sequence of M. bandyopadhyayi was deposited in the GenBank under accession number MZ230377 .

Molecular data: The ssrDNA sequence of Myxobolus chakravartyi (GenBank accession number: MZ 230377) was closest to the sequences of

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Myxobolus auratus ( KX 399851) and several Thelohanellus sp. samples (KP030765, KX881785, KY131789). The sequence similarities fell within the range between 93.4 and 94.7%. Sequences of Thelohanellus caudatus showed a similarity between 92.9 and 94.1%.

Remarks: Spores found in catla specimens corresponded both in measurements and shape to Myxobolus chakravartyi Haldar et al. (1983) species. They differed, however, in three features. Although Haldar et al. (1983) mentioned a triangular thickening at the anterior end of the spores in their description, they failed to present the prominent intercapsular appendix in their figures, which was present in our morphological analysis. On the other hand, the streak of the protuberance in their figures was visible. These authors found their species in the internal musculature inside the eye of a catla specimen. In our case, plasmodia were found only in the fins, most probably in the connective tissue. Based on the strict tissue specificity of Myxobolus spp. we assume that the plasmodia in the eye were rather in contact with connective tissue elements.

Figures

Fig. 11. Myxobolus chakravartyi plasmodia (P) in the fin of a catla in close contact with fin rays (Fr). Mount picture. Bar = 200 μm.

Fig. 12. M. chakravartyi spores from the fin of a catla. Arrow is indicating the charasteristic intercapsular appendix. Inset: deformed spore with the Henneguya like caudal extension. Mount picture. Bar = 10 μm.

Fig. 13. Schematic drawing of spore of M. chakravartyi, a: frontal view, b: frontal view of deformed spore with caudal extension. Bar = 10 μm.