Tinca tinca (Linnaeus, 1758)

Goswami, Urvashi, Cech, abor, alm, Moln, an, ar, Ghosh, Subarna, Bogl, Sellyei, arka, Istv, Czegl, an, edi, Sz, Csaba & ekely, 2022, Morphological and molecular studies on two myxosporean infections of cyprinid fishes: Thelohanellus pyriformis from tench and Thelohanellus cf. fuhrmanni from nase, International Journal for Parasitology: Parasites and Wildlife 18, pp. 119-127 : 120-121

5.1. Infection in tench ( Tinca tinca )

Thelohanellus infection in tench was found in June 2019 in a fish of 29 cm in length caught in Lake Balaton at Balatonszemes (46 ◦ 48 ′ 36.4 ′′ N 17 ◦ 45 ′ 55.9 ′′ E). When inspecting hemibranchia under dissecting microscope, small dark nodules were found in the arteria afferens, which proved to be plasmodia filled with spores of a Thelohanellus sp. When studying the gill filament under a compound microscope round or oval plasmodia were located in the lumen of the arteria afferens ( Fig. 1 ). Round cysts measured 25 × 25 and elongate ones 25 × 160. They contained from 500 to 3000 spores. Each of the eight arches was infected with 2–8 plasmodia. Based on the shape and size of the spores and the specific location, this species was identified as T. pyriformis (Th´elohan, 1892).

5.2. Description of spores

Mature spores ( Fig. 2a and b and 2c ) were pyriform both in frontal and sutural view, slightly tapering toward the anterior end and round at posterior end, 19.0 ± 0.6 l (18.0–19.5) long (n = 50), 8.2 ± 0.54 (7.5–9.0) wide (n = 50) and 7.3 ± 0.25 (7.0–7.5) thick (n = 25). In some spores the anterior end slightly bent. Spore wall formed by two shell valves of equal-size separated by sutural ridge, and light microscopically showing an about 0.55 in thickness. The wall at the posterior pole of the spore thickened showing some nodules on its surface, regarded as sutural notches by Dykov´a and Lom (1987. Single pyriform polar capsule presents close to apex of spore, 8.4 ± 055 (7.5–9.0) (n = 50) long, 4.6 ± 0.3 (4.0–5.0) (n = 50) wide. Polar tubules closely coiled with 9, or 10 turns, arranged perpendicular to the longitudinal axis of capsule. At one side of the polar capsule close to the blunt end a bright nucleus of the

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capsulogenic cell, about 1 in diameter is present. Sporoplasm located at the posterior pole of spore, contains two round nuclei. No iodinophilous vacuole had been seen. At the anterior end of the spore besides the polar capsule two bright round globules (probably the nuclei of the valvogenic cells), about 1 in diameter are located. Some of the spores are surrounded by on average 15.8 × 22.7 mucous envelope ( Fig. 2c arrows).

5.2.1. Taxonomic summary

Host: Tench, Tinca tinca L.

Locality : Lake Balaton, Balatonszemes, Hungary (46 ◦ 48 ′ 36.4 ′′ N 17 ◦ 45 ′ 55.9 ′′ E) .

Site of tissue development: Arteria branchialis afferens.

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-72082. The ssrDNA sequence (1973 bp, long) of T. pyriformis was deposited in the GenBank under accession numbers OM764632.

Prevalence: 1 specimen from 7 fish.

Molecular data: The phylogenetic analysis revealed the closest relative of this species to T. cf. fuhrmanni (present study data) with 96.4% nucleotide sequence identity. 95.1% similarity was found with T. magnacysta (MN540268) and 91.6% similarity was observed to a Thelohanellus species-2018 (MK053786) from intestinal epithelium of the Cobitis paludica in Portugal.

Figures

Fig. 1. Plasmodia (arrows) of Thelohanellus pyriformis in the lumen of arteria branchialis afferens (aa). Arteria branchialis efferens (ae) is uninfected. Histological section. H. and E. staining.

Fig. 2. Spores of Thelohanellus pyriformis a) Schematic drawing of a spore in frontal view, b) Schematic drawing of a spore in sutural view. c) Microscopic photos of spores.