Boros István (szerk.): A Magyar Természettudományi Múzeum évkönyve 52. (Budapest 1960)

Berinkey, L.: Further morphological and osteological investigations on the hybrids of Hungarian Cyprinids

The upper and lower branches of the cleithrum (fig. 4—6) include an obtuse angle in the bleak, there is a spur-like projection anteriorly on the bone (at the tip of the angle), and the upper dorsal branch is almost evenly thick throughout. In the rudd, the two branches include a right angle, there is no anterior spur-like projection, the upper branch is the thickest at the tip of the angle, and from then on it tapers gradually upwards. With regard to these differences, this bone of the hybrid is formed like that of the rudd. However, the dorsal branch of the cleithrum in the bleak is shorter than the ventral one, while the dorsal branch is the longer in the rudd. The length of the ventral branch in that of the dorsal one is 128% in the bleak, 82,8% in the rudd, and 108% in the hybrid. Thus this character seems to be a transitional one, too. Rutilus rutilus (L.) X Scardinius erythrophthalmus (L.) This hybrid was first described also by J ä c k e 1, as Scarclinopsis anceps. The most important differences between the parent-species, the rudd (Scardinius erythrophthalmus

) and the roach (Rutilus rutilus), are as follows. The body of the roach is more elongated, its dorsal and ventral edges not so strongly arched. The upper portion of the head is arched, not so straight as that of the rudd. Its eyes are smaller, its mouth terminal. The front of the dorsal fin begins in the same line with the ventral one. The front of the anal fin is much behind the end of the dorsal. The end of the dorsal fin is midway between the ventral and the anal ones. There is a scaled edge between the ventral and anal fins in the rudd, wanting in the roach. The upper part of the head is straight in the rudd, the mouth turning much upward. The beginning of the dorsal fin is midway between the ventral and anal ones. The anal fin begins in the line demarcating the end of the dorsal one. The caudal peduncle is thick and short. The fin-ray and scale formulas of the roach are D. Ill 9—11, A. Ill 10—11, lin. lat. (39) 41 7—8 46 (47—48). Vertebrae 41—42 (43). Spinae branchiales 3 —4 usually 10. Dentés pharyngeales 6—5, rarely 5—5. The fin-ray and scale formulas of the rudd are D. Ill 8—9 (10), A. Ill (9) 10— —11 (12), lin. lat. (37) 38 ^-42 (43). Vertebrae 37—39. Spinae branchiales 11 — 12. Dentés pharyngeales 3.5 — 5.3. Fig. 4—6. Cieithrum. — Fig. 4. Scardinius erythrophthalmus ; fig. 5. Alburnus alburnus .' fig. 6. Hybrid.