Chondrostoma nasus (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 : 121

5.3. Infection in common nase ( Chondrostoma nasus )

During our long-termed examinations on myxosporean infections of the common nase, Thelohanellus infection was detected only in two cases. Firstly, in 2004 in a 34 cm long nase collected in the Danube close to the city Gyor ˝(46 ◦ 48 ′ 36.4 ′′ N 17 ◦ 45 ′ 55.9 ′′ E). Secondly, in 2019 when Thelohanellus infection was found in one of the six nase of 31–33 cm long caught from the Danube at Nagymaros (47 ◦ 47 ′ 16.9368 ′′ N 18 ◦ 57 ′ 14.9256 ′′ E). In both cases, a single large, flat, 4 × 4 mm size cyst was found on the snout of the specimens. The cysts were visible to the naked eye. Inside the cysts, 5–6 global shape plasmodia were located filled by about 10.000 myxospores.

5.4. Description of spores

Mature myxospores were pyriform both in frontal and sutural view, slightly tapering toward the conical anterior end and rounded at the posterior end 16.3 ± 0.39 (15.5–16.5) long (n = 50), 6.5 ± 0.55 (6.3–7.0) wide (n = 50) and 6.3 ± 0.53 (5.8–7.0) thick (n = 25) ( Fig. 3a, b, c, d ). Myxospore wall formed by two shell valves of equal-size separated by a thick and fairly well marked sutural ridge. Light microscopically in sutural plane, the spore wall was about 0.5–0.6 in thickness but at the posterior end the myxospore thickened and bearing some nodules on its surface. Single flask-shaped polar capsule presents close to apex of spore, 6.5 ± 0.8 (5.5–7.0) (n = 50) long, 3.0 ± 0.1 (3.0–3.2) (n = 20) thick. Polar tubule coiled with 6 turns arranged obliquely to the longitudinal axis of capsule. At one side close to the blunt end of the polar capsule a bright nucleus of the capsulogenic cell, about 1 in diameter is present. Sporoplasm located close to posterior pole of myxospore, containing two round nuclei. At the anterior end of the myxospore besides the thickened polar capsule one or two bright round globules (probably the nuclei of the valvogenic cells) are located. Sutural ridge thickened and fairly well marked. Most of the myxospores surrounded by a pale, oval shape on average 13.5 × 9.0 mucous envelope ( Fig. 3 c, d arrows) attaching to the wall of the myxospore at the anterior pole. The spores of the species resembled to T. fuhrmanni described by Auerbach (1909).

Figures

Fig. 3. Spores of Thelohanellus cf. fuhrmanni. a) Schematic drawing of a spore in frontal view, b) Schematic drawing of a spore in sutural view, c) Microscopic photos of spores in frontal view. A spore in sutural view (inset).