Gobio uralensis Turbanov, Bolotovskiy, Artaev, Gandlin, Levina, Vasil'eva & Levin, 2025, sp. nov.

Gobio uralensis sp. nov. Figs 3, 4, 8 A (English name – Ural gudgeon, Russian name – уральский пескарь) Gobio fluviatilis non Cuvier, 1842 – Kessler 1877: 298. Gobio gobio (non Linnaeus, 1758) – Navozov 1912: 263; Berg 1914: 428 (part.); Bening 1938: 237; Tikhiy 1938: 307; Berg 1949: 640 (part.); Kozhin 1949: 374 (part.); Shaposhnikova 1964: 78; Mitrofanov 1988: 6, fig. 1 (part.); Kottelat 1997: 60 (part.); Bănărescu et al. 1999: 81 (part.); Zinovyev and Baklanov 2007: 54 (part.); Magazov and Rechkalov 2007: 87 (part.); Chibilev and Debelo 2009: 101 (part.); Shevchenko 2018: 122–123. Gobio volgensis non Vasil’eva, Mendel, Vasil’ev, Lusk & Lusková, 2008 – Bogutskaya et al. 2013: 176, figs 35 a, 36 a (part.); Martynova and Vasil’eva 2021: 529 (part.), figs 1, 2; Vasil’eva et al. 2023: 503 (part.). Type material. Holotype • (IBIW_FS_454) 97.7 mm SL, Russia, Republic of Bashkortostan, Abzelilovsky Distr., near Ryskuzhino, Bolshoy Kizil River, 53.3161°N, 58.3351°E, 24 Aug. 2020, O. N. Artaev, A. A. Bolotovskiy, I. V. Pozdeev, I. S. Turbanov leg. Paratypes • 4 spec. (IBIW_FS_455) 70.3–110.4 mm SL, 3 spec. (ZISP 57042) 69.8–73.4 mm SL, 3 spec. (ZMMU P-24633) 68.1–75.7 mm SL, same data as holotype. Additional material. • 7 spec. (IBIW_FS_456) 40.9–64.4 mm SL, same data as holotype and paratypes • 4 spec. (IBIW_FS_457) 34.8–42.7 mm SL, Russia, Orenburg Region, Pervomaysky Distr., near Lyashevo, Chagan River, 51.8514°N, 51.4965°E, 22 May 2021, O. N. Artaev, A. A. Bolotovskiy, A. V. Kutuzov leg. • 1 spec. (IBIW_FS_458) 72.5 mm SL, Russia, Orenburg Region, Saraktashsky Distr., near Krasnogor, Ural River, 51.5591°N, 56.1224°E, 23 May 2021, O. N. Artaev, A. A. Bolotovskiy, A. V. Kutuzov leg. • 5 spec. (IBIW_FS_459) 38.9–50.3 mm SL, 32 spec. (IBIW FS _ 465) 27.9–39.9 mm SL, Russia, Orenburg Region, Saraktashsky Distr., near Nikolskoe, Sakmara River, 52.0018°N, 55.7371°E, 24 May 2021, O. N. Artaev, A. A. Bolotovskiy, A. V. Kutuzov leg. • 2 spec. (IBIW_FS_460) 85.0– 87.5 mm SL, Russia, Orenburg Region, Sakmarsky Distr., near Svetlyi, Kargalka River, 52.0835°N, 55.1283°E, 24 May 2021, O. N. Artaev, A. A. Bolotovskiy, A. V. Kutuzov leg. • 11 spec. (IBIW_FS_461) 47.2–80.2 mm SL • 15 spec. (IBIW FS _ 466) 33.7–47.6 mm SL, Russia, Orenburg Region, Oktyabrsky Distr., Oktyabrskoe, Bolshoy Yushatyr River, 52.3631°N, 55.5008°E, 24 May 2021, O. N. Artaev, A. A. Bolotovskiy, A. V. Kutuzov leg. • 1 spec. (IBIW_FS_462) 71.8 mm SL, Russia, Republic of Bashkortostan, Kugarchinsky Distr., near Aznagulovo, Nakas River, 52.6431°N, 56.2436°E, 24 May 2021, O. N. Artaev, A. A. Bolotovskiy, A. V. Kutuzov leg. • 17 spec. (IBIW_FS_463) 57.9–82.1 mm SL, Russia, Republic of Bashkortostan, Zianchurinsky Distr., near Verkhniy Muinak, Uskalyk River, 51.9687°N, 56.6878°E, 25 May 2021, O. N. Artaev, A. A. Bolotovskiy, A. V. Kutuzov leg. • 5 spec. (IBIW_FS_464) 37.2–81.4 mm SL, Russia, Republic of Bashkortostan, Zianchurinsky Distr., upstream Itkulovo, Assel River, 51.9047°N, 56.8683°E, 25 May 2021, O. N. Artaev, A. A. Bolotovskiy, A. V. Kutuzov leg. Etymology. The adjective uralensis comes from the name of the Ural River, which literally means lives in the basin of this river. Diagnosis. Gobio uralensis sp. nov. is distinguished by a combination of characters, none of which is unique, as follows: predorsal length 47.4–52.6 % SL; postdorsal length 36.3–42.1 % SL; body depth 17.4–23.7 % SL; prepelvic length 49.8–56.8 % SL; preanal length 70.2–75.2 SL; snout length 40.9–48.8 % HL; interorbital width 22.3–29.6 % HL; ratio of caudal peduncle length to caudal peduncle depth 2.0–2.8; pharyngeal teeth in two rows, 3.5–5.3; anal fin branched rays 6 1 / 2; number of lateral line scales 39–45, mean 42.1; 12 (mode) predorsal vertebrae; the breast between the pectoral fins is naked; lower lip is interrupted in middle, with a notch between narrower anterior and widening posterior parts. Description. General appearance shown in Fig. 3. Morphometric and meristic data are given in Tables 2 – 4. Largest recorded specimen – 110.4 mm SL. Morphometrics. The body and the caudal peduncle are moderately compressed; the minimum body depth is somewhat greater than the width of the caudal peduncle at the level of the last anal ray. Predorsal length is somewhat more than postdorsal length. The distance between pectoral and pelvic-fin origins is somewhat more than the distance between pelvic and anal-fin origins. The anus is closer to the insertion of the anal fin than to the origin of the pelvic fins; the pelvic fin reaches beyond the anus. Barbels are moderately long; they are usually less than 1 / 3 of the head length and reach up to the middle of the eye but never reach to its posterior edge. Paired fins are moderately long: pectoral fins never reach the pelvic fin insertion; ventral fins never reach the anal fin insertion. The eye is large with a diameter of 17.6–25.2 % of the head length, an eye diameter of 2.2–3.3 times in head depth, and 1.0–1.5 times in interorbital width. The snout is pointed; its length is somewhat longer than the postorbital length. Caudal peduncle is 2.0–2.8 times longer than depth. Meristics. Dorsal fin margin is concave, with 3 unbranched and 7 1 / 2 branched rays (only one specimen had 8 1 / 2 rays); anal fin margin is concave or straight, with 3 unbranched and 6 1 / 2 branched rays; pectoral fin branched ray numbers vary within 13–17 (mode 16 and 15 in left and right, respectively); and pelvic fin branched ray numbers vary within (5) 6–8 (mode 7). The shape of the caudal fin is variable; the two lobes are sharpened or rounded, with a notch in the middle. Body is covered by scales. Lateral line includes 39–45 total scales (mode 42) and 11–15 circumpeduncular scales (mode 12). Two-five gill rakers (modes 4 and 5) on outer side of first gill arch. Pharyngeal teeth are in two rows, 3.5–5.3, slightly hooked at tip (Fig. 4). Total vertebrae 39–42 (mode 40), 20–22 (mode 21) abdominal, including 11–13 predorsal and 18–21 (mode 19) caudal, including 1–3 preanal and 16–19 postanal vertebrae. The radiograph of the holotype is given in Fig. 5. Qualitative characters. The breast in front of the posterior edge of the base of the pectoral fins usually lacks scales; some individuals have 1–3 scales along the midline towards the throat [character state 1 following Naseka et al. (2006)] (Fig. 8 A). Coloration. Body is dark olive-brown above, merging into a light silvery underside. There are large, more or less rounded 6–14 (often 10) blotches on flank located along the lateral line. The color of the fins corresponds to the color of the body with several rows of small dark dots on the dorsal and caudal fins. Live coloration is given in Figs 3 A, D, E, 8 A. Distribution. The type specimens were collected from the Bolshoy Kizil River, a tributary of the Ural River, near Ryskuzhino (53.3161°N, 58.3351°E), Republic of Bashkortostan, Russia (see Fig. 6). All other gudgeons genetically confirmed as the same species were caught in different locations in the Ural River basin (see materials). Although we suppose that the whole Ural River basin is inhabited by the Ural gudgeon, one may not exclude that some parts of the extended Ural drainage are inhabited by other species. According to Shaposhnikova (1964), the gudgeon is widespread throughout the Ural River. The gudgeon is especially abundant in the mountain tributaries of the Ural and in its upper reaches, where it is numerous in riffles and sandbanks; this is partly confirmed by the data of Martynova and Vasil’eva (2021) as well as by our observations. Biology. In the Ural River near Orenburg, the gudgeon spawns from the middle of the twentieth days of April to early or mid-May, but individual spawning specimens are caught throughout the summer (Navozov 1912). Spawning is multiple (Shaposhnikova 1964). In all areas of the Ural basin, regardless of the time of year, larvae of Tendipedidae (Insecta: Diptera) are the main food item beginning from the first year of life. In addition, larvae of Heleidae (Insecta: Diptera), Oligochaeta (Annelida), larvae of Ephemeroptera (Insecta), Gastropoda (Mollusca), plant remnants, and diatom algae were also detected. In juveniles (up to 47 mm), Cladocera and Copepoda (Crustacea) as well as diatoms and other algae predominated in the food bolus (Shaposhnikova 1964). Comparative remarks. As we have already noted above, in the earliest faunal studies, the gudgeons from the Ural River basin were identified as Gobio gobio. However, according to the latest data, G. gobio is distributed in the basins of the Atlantic Ocean, the North, Baltic and White Seas (including Great Britain and the upper Danube basin), but not in the Caspian Sea basin (Dyldin et al. 2023). At the same time, G. gobio is well differentiated from G. uralensis sp. nov. by a narrow lower lip with no interception between the anterior and posterior parts (vs. the lower lip is interrupted in the middle, with a groove between narrower anterior and wider posterior parts in G. uralensis sp. nov.); its minimum body depth always exceeds 30 % of the length of the head and 40 % of the length of the caudal peduncle (Vasil’eva et al. 2023). Geographically, the two species closest to the new species are the Siberian gudgeon G. sibiricus (Figs 7 C, D, 8 C), distributed from the Ob’ to Lena basins (including the Nura River in Kazakhstan), and G. volgensis (Figs 7 A, B, 8 B), known from the Volga River basin. In turn, the new species is morphologically almost indistinguishable from the Volga gudgeon; therefore, the Ural populations were previously identified as G. volgensis (Vasil’eva et al. 2023). According to the materials of this study, G. volgensis from the Chusovaya, Belaya, Ashkadar and Dema rivers (neighboring rivers of the Volga River basin to the typical habitats of the Ural gudgeon) have a slightly higher total number of lateral line scales – a range 41–45 and median of 42.5 (vs. a range 39–45, median of 42 in G. uralensis sp. nov.), as