taxonID	type	description	language	source
EB49A1E08582554484349144B85A6521.taxon	description	Figs 2, 3, 8 English name: Ayuk minnow Russian name: Аюкский гольян	en	Artaev, Oleg N., Turbanov, Ilya S., Bolotovskiy, Aleksey A., Gandlin, Alexander A., Levin, Boris A. (2025): A new super narrow-ranged endemic Phoxinus minnow (Leuciscidae) from the Caucasus. Zoosystematics and Evolution 101 (3): 1137-1154, DOI: 10.3897/zse.101.153548
EB49A1E08582554484349144B85A6521.taxon	diagnosis	Diagnosis. Phoxinus ayukensis sp. nov. is distinguished from other European and circum-Black Sea Phoxinus species (P. abanticus, P. adagumicus, P. bigerri, P. chrysoprasius, P. colchicus, P. csikii (Clade 5), P. dragarum, P. fayollarum, P. isetensis, P. karsticus, P. krkae, P. lumaireul (Clade 1 b, 1 a), P. marsilii (Clade 9), P. radeki, P. septimaniae, and P. strandjae Drensky, 1926) by increased number of scales in the lateral series 87 – 105 (mean 97.7); from species from Eastern Europe and the Caucasus (P. adagumicus, P. chrysoprasius, P. colchicus and P. isetensis) by increased frequency of occurrence of seven rays in the pelvic fin (ca. 35 %) and increased numbers of scales between first unbranched rays of dorsal and anal fins (32 – 41, mean 36.7).	en	Artaev, Oleg N., Turbanov, Ilya S., Bolotovskiy, Aleksey A., Gandlin, Alexander A., Levin, Boris A. (2025): A new super narrow-ranged endemic Phoxinus minnow (Leuciscidae) from the Caucasus. Zoosystematics and Evolution 101 (3): 1137-1154, DOI: 10.3897/zse.101.153548
EB49A1E08582554484349144B85A6521.taxon	description	Description. The live and preserved appearance as well as radiograph of holotype is shown on Fig. 2, general appearance of live female and male of Phoxinus ayukensis sp. nov. from type locality is shown on Fig. 3, morphometrics of holotype, paratypes and additional material from the type locality with level of significance of sex-related differences are given in Table 2, meristic and qualitative characters for specimens from type locality are given in Table 3, primary morphological data for specimens from the type locality (holotype, paratypes and additional material) are given in Suppl. material 1, morphometrics of P. ayukensis sp. nov., P. isetensis, P. adagumicus, P. chrysoprasius and P. colchicus with their comparison are given in Suppl. material 2, meristic and qualitative characters of P. ayukensis sp. nov. and other Phoxinus spp. are given in Suppl. material 3. Morphometrics (Table 2, Suppl. materials 1, 2). The new species has a rather small size — the maximum SL is 54.8 mm. The new species has eye horizontal diameter 7.0 % HL in holotype, 7.0 – 8.7 % in paratypes and additional material from type locality; caudal peduncle width 7.9 % SL in holotype, 7.0 – 8.4 % in paratypes and additional material from type locality; head length 145.2 % body depth in holotype, 120.2 – 152.9 % in paratypes and additional material from type locality. Meristics (Table 3, Suppl. material 3). Dorsal fin with 3 unbranched and 7 ½ branched rays. Anal fin with 3 unbranched and 7 ½ branched rays. Pectoral fin with 14 – 16 rays, often 15 – 16. Pelvic fins with 7 – 8 rays. Caudal fin with 19 rays (rarely 18 and 20 rays). Number of dorsal procurrent caudal-fin rays 10 – 13. Number of ventral procurrent caudal-fin rays 6 – 10. Pharyngeal teeth are two-rowed, with the common formula 2.5 – 4.2. However, appr. 30 % of individuals exhibit a reduction of the second row to a single tooth, at least on one pharyngeal bone. Total number of vertebrae in the holotype 40, 39 – 41 in the paratypes, and in the add. material, commonly 40. Number of abdominal vertebrae in the holotype 22, 21 – 23 in the paratypes, and 21 – 24 in the add. material, commonly 22 or 23. Number of caudal vertebrae in the holotype 18, 17 – 19 in the paratypes, and 16 – 19 in add. material, commonly 17 and 18. Number of predorsal abdominal vertebrae in the holotype 14, 14 – 15 in the paratypes, and in the add. material, commonly 14 or 15. Number of anal-fin pterygiophores in front of the first caudal vertebrae in the holotype 5, 4 – 7 in the paratypes, and in the add. material, commonly 5 or 6. Difference in the number of abdominal and caudal vertebrae in the holotype 4, 2 – 6 in the paratypes, and 2 – 8 in the add. material, commonly 4 – 6. Lateral line incomplete and discontinuous. Total number of scales in the lateral line series 87 – 105, mean 97.7. Total number of lateral-line (pored) scales 9 – 54, mean 30.5. Number of scales between bases of dorsal and anal fins 32 – 41, mean 36.7. Number of circumpeduncular scales 41 – 49, mean 45.1. Gill rakers on the first left gill arch 7 – 9, mean 7.9. Qualitative characters. Free margin of the dorsal fin is mainly slightly convex, rarely straight; anal fin most often slightly convex, rarely straight or slightly concave. Origin of anal fin in half the cases at the level of posterior insertion of the dorsal fin, often slightly ahead, rarely slightly behind. Third-fourth type of breast scalation with a predominance of fourth type. Coloration. Outside the spawning period, males and females are olive-yellow-green in color with very little contrast between horizontal zones and vertical stripes. In general, females have less and males have more saturated coloration. The horizontal stripe along the back of the body is practically not expressed in adults and weakly expressed in juveniles. Sexual dimorphism. There are significant differences in 7 out of 41 morphometric characters (Table 2). In addition to classical sex characteristics in Phoxinus minnows (narrower pectoral fins and less bright colors in females), females have a lower head depth at nape relative to the length of the head and body and greater pectoral – pelvic-fin origin length.	en	Artaev, Oleg N., Turbanov, Ilya S., Bolotovskiy, Aleksey A., Gandlin, Alexander A., Levin, Boris A. (2025): A new super narrow-ranged endemic Phoxinus minnow (Leuciscidae) from the Caucasus. Zoosystematics and Evolution 101 (3): 1137-1154, DOI: 10.3897/zse.101.153548
EB49A1E08582554484349144B85A6521.taxon	etymology	Etymology. The new species is named after the Ayuk (= Burlachenkova Shchel, Peshchernaya Shchel, Semenovskaya Shchel) Stream – the only known habitat area. Name of the Ayuk Stream apparently comes from the Adyghe language word “ ayuko ”, which means “ unfriendly valley ”. Ayukensis – an adjective.	en	Artaev, Oleg N., Turbanov, Ilya S., Bolotovskiy, Aleksey A., Gandlin, Alexander A., Levin, Boris A. (2025): A new super narrow-ranged endemic Phoxinus minnow (Leuciscidae) from the Caucasus. Zoosystematics and Evolution 101 (3): 1137-1154, DOI: 10.3897/zse.101.153548
EB49A1E08582554484349144B85A6521.taxon	distribution	Distribution and habitats. New species has an extremely narrow range and is known from the Ayuk Stream only in the area of the Ayuk waterfalls and above them (Fig. 4). The total length of the river is about 12 km, the upper stream of which (5 – 7 km) is inhabited by the core population. Some individuals occasionally migrate downstream to the confluence with the Chepsi River (about 5.5 km) (Fig. 5). In the summer, the water level is low, surface runoff stops, and water pools remain in the deep parts of the riverbed, which are apparently supplied by interstitial waters (Fig. 4 A). Such water pools are inhabited by P. ayukensis sp. nov. only.	en	Artaev, Oleg N., Turbanov, Ilya S., Bolotovskiy, Aleksey A., Gandlin, Alexander A., Levin, Boris A. (2025): A new super narrow-ranged endemic Phoxinus minnow (Leuciscidae) from the Caucasus. Zoosystematics and Evolution 101 (3): 1137-1154, DOI: 10.3897/zse.101.153548
