Myxobolus dermiscalis Kaur et al. (2016)

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 : 21-22

3.3. Myxobolus dermiscalis Kaur et al. (2016) ( Figs. 8–10 )

Round-shaped plasmodia ( Fig. 8 ) with a diameter of 700 to 1,500 were located in the superficial tissues of the scale. They occurred in 4 out of 13 rohu specimens from the fish farm. Plasmodia contained 800 to

21

2,000 spores.

Spores ( Figs. 9 and 10 ) short ellipsoidal in frontal view and lemon shaped in sutural view. Spores 10.6 ± 0.44 (9.9–11.2) long, 8.5 ± 0.3 (8–8.8) wide and 6–6.2 thick. Two polar capsules elongated pyriform, uniform in size, 5.4 ± 0.3 (5–5.8) long and 2.5 ± 0.22 (2.2–2.7) wide. Polar tubules not seen. The proximal end of the spore has a shortflattened plate. Nuclei of the sporoplasm and polar capsules not seen. Iodinophilous vacuole and mucous envelope not found. The thickness of the spore wall 0.7–0.8.

Host: Rohu Labeo rohita Hamilton.

Locality: Naihati, Battala market (22.89 ◦ N 88.42 ◦ E) (on the Kalyani expressway)

Site of infection: scales.

Prevalence of infection: 4 specimens from 13 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-72079. The ssrDNA sequence of M. bandyopadhyayi was deposited in the GenBank under accession number MZ230378 .

Molecular data: ssrDNA sequence (GenBank accession number: MZ 230378) of the parasite was 99.4% similar to Myxobolus dermiscalis ( KM 092529) and 98.8% similar to a Myxobolus sp. sample ( KM 401439) which was also isolated from the scales of rohu. These three sequences formed a monophyletic clade with maximum bootstrap. As the closest relatives on the phylogenetic tree, the sequences of Myxobolus rewensis ( MZ 230381, this paper) and Thelohanellus sp. ( KM 401440) showed 91.8% and 91.6% similarity, respectively.

Remarks: The collected spores were in ethanol-fixed preserved state and showed only the most important figures for identification. The horizontal flattened plate at the anterior end of the spores resembled closely to the figures presented by Kaur et al. (2016). However, the authors made some mistakes in measuring oocysts. These authors measured the size of spores as 5.84–7.84 × 3.98–5.98 μm; however, the bar shown on spore photos and line drawings prove that the spores were larger than 10 μm. Molecular data deposited to the GenBank by the latter authors showed a close similarity to our data; moreover, sequences in the GenBank (KM401439, Myxobolus sp. KLT, 2014) from the scale of the rohu differed from our sequences only in 0.01%.

Figures

Fig. 8. Myxobolus dermiscalis plasmodia (P) in the scale of a rohu. Mount picture. Bar = 500 μm.

Fig. 9. M. dermiscalis spores in frontal view. Mount picture. Bar = 10 μm.

Fig. 10. Schematic drawing of spore of M. dermiscalis, a: frontal view, b: sutural view. Bar = 10 μm.