FISHES OF THE FAMILY CYPRINIDAE IN THE WATER BODIES OF UKRAINE - V. V. Zamorov - 2015

GENUS CHONDROSTOMA AGASSIZ (NASHES)

Key to species of the genus Chondrostoma

1 (2). Maximum body depth is typically less than 26% of standard body length (to the end of the scaled area). Pharyngeal Teeth typically 6-6, occasionally 7-6. Lateral line typically with 60-63 (52-66) scales.

Scales of the Common Nase - C. nasus

2 (1). Maximum body depth is typically greater than 26% of standard body length (to the end of the scaled area). Pharyngeal teeth typically 6-5, occasionally 5-5 or 6-6. Lateral line typically with 55-57 (50-62) scales. Scales of the Vimba nase - C. variabile

Common Nase - Chondrostoma nasus (Linnaeus)

Morphological features: D III (IV) (8) 9 (10); A III (IV) 9-12; P I 16; V II 8; C I 17 I; l. l. (50, 51) 52-66 (67); vert. 43-48; sp. br. 26-32 (34); d. f. 6-6 (7-6). Maximum body length up to 45 cm, more commonly 25-30 cm, weight up to 2000 g, lifespan up to 10 years (Fig. 25).

Class="center">

Fig. 25. Common nase (Chondrostoma nasus)

Body slightly elongated, moderately deep, laterally compressed. Maximum body depth constitutes 22.1–26.5% of standard body length (l) and exceeds maximum body thickness by 1.7–1.9 times. The caudal peduncle is moderately short, its length reaching 1/5 of l. The antedorsal distance equals 1/2 of l, the postdorsal distance is noticeably smaller, and the anteventral distance is slightly larger. The anteanal distance is about 72% of l, P - V is 28–29% of l, and V - A is 20–22% of l. The length of P is 1.2 times less than P - V, and the length of V is 1.4 times less than V - A. The base length of D is 12–13% of l, while the base length of A is slightly smaller. The height of D reaches, whereas the height of A falls well short of, 1/5 of l. The length of the caudal fin lobes is 1/4–1/5 of l, and the HEAD length is slightly smaller. Head height as a percentage of head length is 70–73%. Snout length approaches ¹/₃ of the head length, and the postorbital distance approaches ¹/₂, meaning the eye is positioned much closer to the anterior margin of the head than to the posterior one. Eye diameter is ¹/₄–¹/₅ of the head length. Interorbital width is about 40% of the head length.

In Ukraine, it occurs in all well-oxygenated flowing waters, ranging from the Danube delta and the rivers of Transcarpathia to the Dnieper river basin inclusive.

Volga nase - Chondrostoma variabile Jakovlev

Morphological features: D III (IV) 8-10; A III 9-11; P I 16; V II 8; C I 17 I; l. l. (52) 53-61 (62, 63); vert. 38-46; d. f. 6-5 (6 - 6, 5 - 5). Maximum body length up to 30 cm, weight up to 200 g, lifespan up to 8 years (Fig. 26).

Fig. 26. Volga nase (Chondrostoma variabile)

Body fairly elongated, moderately deep, slightly compressed laterally. In various Water bodies (Don and Volga river basins), the following average plastic (morphometric) characteristics are observed. As a percentage of standard body length (l), the maximum body depth is 24.5–28.5% and exceeds the minimum body depth (h) by 2.4–2.6 times. The antedorsal distance equals half the body length or slightly less, and the postdorsal distance is approximately 40.0% of l. The anteventral distance slightly exceeds 1/2 of l, meaning the pelvic fins originate slightly behind the vertical line passing through the Origin of the dorsal fin base. The midpoint of the anal fin base, which constitutes 10.8–14.1% of l, lies on the same vertical line as the midpoint of the postdorsal distance.

The base length of D slightly exceeds the base length of A. The height of D is 18.7–23.9% of l and is 1.3–1.4 times greater than the height of A. Pectoral and

pelvic fins are short, their tips falling well short of the bases of the adjacent fins situated behind them. The pectoral fin is 1.5 times shorter than the P - V distance, and the pelvic fin is shorter than V - A. The caudal peduncle is moderately elongated, with its length nearly reaching ¹/₅ of l. The length of the caudal lobes ranges between ¹/₅ and ¹/₄ of l, with the lower lobe being shorter than the upper one. The tips of all fins, especially the caudal fin, are pointed. The caudal fin has a fairly deep notch, while the other fins have no noticeable emarginations along their margins. The head is relatively small, its length slightly exceeding ¹/₅ of l. Head height expressed as a percentage of head length is 67.7–72.1%. Snout length goes into head length three to four times, and the postorbital distance goes into it slightly more than two times, meaning the eye is positioned much closer to the anterior margin of the head than to the posterior one. Eye diameter ranges from ¹/₄ to ¹/₆ of the head length. Interorbital width is 34.9–38.4% of the head length.

In Ukraine, it is found exclusively in the Siverskyi Donets river basin. It is a fairly rare fish with low population numbers, listed in the Red Data Book of Ukraine.