Phoxinus isetensis ( Georgi, 1775 )

Artaev, Oleg N., Bolotovskiy, Aleksey A., Turbanov, Ilya S., Gandlin, Alexander A., Kutuzov, Aleksey V., Levina, Marina A., Melentev, Danila A., Pozdeev, Ivan V., Borisov, Mikhail Ya. & Levin, Boris A., 2024, Forgotten for two centuries: redescription of Phoxinus isetensis (Georgi, 1775) (Cypriniformes, Leuciscidae) – the most widespread minnow in Europe, Zoosystematics and Evolution 100 (3), pp. 1155-1173 : 1155-1173

Phoxinus isetensis ( Georgi, 1775)

Figs 3 , 4 English name: Northern Minnow; Russian name: Северный гольян

Cyprinus phoxinus – Linnaeus 1758: 322 (Europa (part )); Falk 1786: 432 (Volga, Tsaritsa, Elshanka, Sarpa, etc.); Fischer 1791: 258 (Livonia); Hupel 1777: 467 (Liffland and Estonia).

Cyprinus aphya – Linnaeus 1758: 323 (European rivers (part )); Fischer 1791: 258 (Livonia); Georgi 1775: 881 (Sukhona River); Falk 1786: 429 (Kama R. and its tributaries).

Cyprinus (without Latin species name) – Lepechin 1771: 491 (circa Catharinopolin).

“ Галïанъ ” or “ солдатъ ” (without Latin species name) – Lepechin 1772: 309 (upstreams of the Isset, Chusovaya, and Tura rivers).

Cyprinus , “ Krasnosobik ” or “ Soldat ” (without Latin species name) – Georgi 1775: 550 (Iset River).

Cyprinus isetensis Georgi 1775: 621 (Chusovaya River).

Cyprinus galian Gmelin 1789: 1421 (vicinities of Yekaterinburg).

Phoxinus rivularis – Wałecki 1864: 50 (Neman River).

Phoxinus laevis – Kessler 1864: 124 (Neva River); Kessler 1870: 268 (Volga, Samara basins, Khmelevka creek near Vasilsursk); Warpachowski 1889: 61 (Volga R. system in Nizhny Novgorod province); Sabaneev 1892: 423 (Yaroslavl and Perm province, near Moscow: rivers Lichoborka and Sinichka (trib. of Jausa R.), Moskva R. at Kamenny most); Dybowski 1862: 105 (Livonia).

Tinca phoxinus – Plater 1861: 37, 63 (Daugava River).

Phoxinus phoxinus – Berg 1912: 260 ( Finland, Kola region, European rivers of the Arctic Ocean basin); Berg 1923: 166 (in Russia all over); Berg 1932: 368 (in Arctic Ocean basin from Murmansk eastward, Volga basin upstream Syzran (include Kama and Oka rivers), possible in Ural River); Berg 1949: 588 (same place); Reshetnikov et al. 2003: 301 (widespread in Europe (part )); Kottelat and Freyhof 2007: 228 (Scandinavia and Russia’s northernmost extremity; Upper and middle Volga, Ural).

Phoxinus isetensis – Dyldin et al. 2023: 36 (Arctic Ocean basin, from Murman coast to East Siberian Sea basin (part )).

Phoxinus sp. – Dyldin et al. 2023: 37 (Europe, in North Sea, Baltic Sea basins (including Gulf of Finland and Neva River), and northern Caspian Sea basin (Upper Volga River, including Kama and Oka rivers, probably in Ural River )).

Type material.

Neotype, female (SL 63.9 mm, IBIW_FS_422 , Genbank Accession numbers PP 538745 – COI, PP 548200 – cyt b), Russia, Sverdlovsk Region, Ob River basin, Severka River (Tobol River basin) upstream Severka village near Yekaterinburg , 56.8830 ° N, 60.2716 ° E, 21 June 2023, O. N. Artaev, I. S. Turbanov, A. A. Bolotovskiy leg.

Additional material.

see Suppl. material 1.

Comparative material.

see Suppl. material 1.

Etymology.

Since Lepechin (1771: 491) described species from the vicinity of Yekaterinburg, it can be assumed that Georgi (1775: 621) (see taxonomic remarks) gave its name to the Iset River, flowing through Yekaterinburg.

Diagnosis.

Phoxinus isetensis is distinguished from other European minnows ( P. adagumicus , P. chrysoprasius , P. colchicus , P. csikii , P. krkae , P. lumaireul (Clade 1 a and Clade 1 b), P. marsilii , P. septimaniae , P. strandjae , and Phoxinus sp. (Clade 2) by having a number of total vertebrae (39–43, mean 41.0, mode 41) and a number of caudal vertebrae (16–21, mean 18.9, mode 19).

Phoxinus isetensis is further distinguished from minnows from Eastern Europe ( P. adagumicus , P. chrysoprasius , and P. colchicus ) by a longer caudal peduncle (caudal peduncle length 2.5–3.7, mean 3.1 times caudal peduncle depth); fewer circumpeduncular scales (28–45, mean 35.3); fewer scale rows above the lateral line (10–21, mean 15.1); and a combination of characters, none of which is unique, as follows: eye horizontal diameter 5.9–8.8 % SL, mean 7.2 and eye horizontal diameter 23.4–33.8 % HL, mean 28.1; depth of caudal peduncle 6.6–9.0 % SL, mean 7.7 in females and 7.2–9.5, mean 8.2 in males; caudal peduncle length 20.5–26.9 % SL, mean 23.9 in females and 22.9–27.7 mean 25.1 in males; 8–16 scale rows below lateral line (mean 11.2, mode 11) (Suppl. materials 3, 4).

Description.

The live and preserved appearance as well as radiograph of neotype is shown on Fig. 3 , general appearance of live specimens of Phoxinus isetensis from different basins is shown on Fig. 4 , morphometrics of neotype and additional material from the type locality with level of significance of sex-related differences are given in Table 1 , meristic and qualitative characters for specimens from the type locality are given in Table 2 , and primary morphological data for specimens from the type locality (neotype and additional material) are given in Suppl. material 2, the meristic and qualitative characters of P. isetensis and Phoxinus spp. are given in Suppl. material 4, the morphometrics of P. isetensis , P. adagumicus , P. chrysoprasius , and P. colchicus and their comparison are given in Suppl. material 3.

Morphometrics (Table 1 , Suppl. material 3). The maximum size among studied specimens 76.3 mm SL. The species has a slender and elongated caudal peduncle. The caudal peduncle depth 6.9 % SL in neotype, 6.9–8.8 % SL in additional material from type locality, and 6.6–9.5 % SL in other additional materials (here and further – from basins of Caspian, Baltic, Barents, and Kara seas); caudal peduncle depth 28.7 % in caudal peduncle length in neotype, 28.7–36.5 in additional material from type locality, and 26.9–40.6 in other additional material; caudal peduncle depth 3.5 times the caudal peduncle length in neotype, 2.9–3.4 in additional material from type locality, and 2.5–3.7 in other additional material. The species has a slender body, body depth at dorsal-fin origin 18.0 % SL in neotype, 15.9–20.0 in additional material from type locality, and 14.7–21.6 in other additional material. Eyes larger (horizontal eye diameter: 26.2 % HL in neotype, 25.3–29.6 in additional materials from type locality, 23.4–33.8 in other additional).

Meristics (Table 2 , Suppl. material 4). Dorsal fin with 3 (very rarely 2) unbranched and (8) 7 ½ (6) branched rays. Anal fin with 3 unbranched and (6) 7 ½ (8) branched rays. Pectoral fin with 14–20, commonly 16–18 rays. Pelvic fin with (7) 8 (9) rays. Caudal fin with (18) 19 (20) rays.

Among 135 individuals, the most common pharyngeal teeth formula is classic for the genus 2.5–4.2 (n = 102) (Fig. 5 A ; Suppl. material 4). Other variants are 2.5–4.1 (n = 10), 2.4–4.2 (n = 8), 1.5–4.2 (n = 4), 2.5–5.2 (n = 3), 1.5–4.1 (n = 2), 2.4–4.1 (n = 2), 2.3–4.2 (n = 1), 2.5–4.3 (n = 1), 2.3. 5 – 4.3. 2 (n = 1). Among those one is exceptionally rare for phoxinin fishes – three-rowed formula 2.3. 5 – 4.3. 2 that was recorded in an individual from the Tsna R., Baltic Sea basin.

Forty-two total vertebrae in neotype, 40–42 in additional material from type locality, and 39–43 in other additional material from basins of Baltic and Barents seas, Volga and Ob rivers, commonly 41 vertebrae. Twenty-one abdominal vertebrae in neotype, 21–23 in additional material from type locality, and 21–24 in other additional material from basins of Baltic and Barents seas, Volga and Ob rivers, commonly 21–23 vertebrae. Twenty-one caudal vertebrae in neotype, 17–21 in additional material from type locality, and 16–21 in other additional material from basins of Baltic and Barents seas, Volga and Ob rivers, commonly 18–20 vertebrae. Fourteen predorsal vertebrae in neotype, 14–16 in additional material from type locality, and 13–16 for other additional material from basins of Baltic and Barents seas, Volga and Ob rivers, commonly 14–15 vertebrae. Three anal-fin pterygiophores in front of the first caudal vertebrae in neotype, 3–6 in additional material from type locality, and 3–7 in other additional material from basins of Baltic and Barents seas, Volga and Ob rivers, commonly 4–6 pterygiophores. Difference between numbers of abdominal and caudal vertebrae zero in neotype, zero to 6 in additional material from type locality, and zero to 7 for other additional material from basins of Baltic and Barents seas, Volga and Ob rivers, commonly 2–5.

Seventy-one to 103 (mean 85.7) total number of scales in the lateral series. Lateral line incomplete and interrupted. The relative number of total lateral-line (pored) scales varies greatly from 12 % to 99 %, mean 61 %. Five to 11 (commonly 6–9) scale rows on breast patches. 28–45 (mean 35.2) circumpeduncular scales. Ten to 21 (mean 15.1) scale rows above lateral line. Eight to 14 (16), mean 11.2 scale rows below lateral line.

Seven to 10 (mode 8) gill rakers (in series from type locality) on first arch.

Qualitative characters. Pectoral fins do not reach the beginning of pelvic fins in females and most of the males (ca. 75 %). In the most specimens (ca. 85 %) tip of the upper lip above horizontal level of lowest point of the eye and in about 5 % of specimens – at this level. Origin of anal fin is mainly ahead or at vertical level of posterior insertion of the dorsal fin (ca. 45 % for each form), rarely behind (ca. 8 %). Free margin of the dorsal fin is mainly straight or slightly convex, rarely slightly concave; anal fin most often slightly concave and straight, rarely slightly convex. 3 rd – 6 th type of breast scalation (mode 4 th type, often 3 th type, 5 th and 6 th type are less common) (Fig. 5 B , Suppl. material 4).

Coloration. Males and females outside of spawning have predominantly brown coloring of the upper half of the body and light lower part in males and white in females (Fig. 4 ). Juveniles often show a large contrast: the black horizontal stripe and the white belly. During spawning, color of both sexes becomes much brighter, the color of the sides is dominated by green (many males become dark green, almost black), in front, it is mixed with golden, less often purple and red. In males, as well as some females, the lips and lower jaw, as well as body at the bases of the pectoral, pelvic, and anal fins, become red. The operculum is blue and the suboperculum is yellow in both sexes, but coloration is much more pronounced in males. In both sexes, the bases of ventral and anal fins are light blue. The specimens preserved in formalin had a yellowish color, which is somewhat darker with a brown tint in the upper parts.

Sexual dimorphism. Significant differences are observed in 18 out of 41 morphometric characters (Table 1 ). In general, females have smaller relative anal (anal-fin depth), dorsal (dorsal-fin depth), pelvic (pelvic-fin length), and pectoral fins (pectoral-fin length), a greater predorsal length, and pectoral – pelvic-fin origin length. In females, the pectoral fins never reach the pelvic fins, while in ca. 25 % of males, reach.

Taxonomic remarks.

According to the early literary sources reviewed in Berg (1912), the first name within the range of species is Cyprinus isetensis , given by Georgi (1775: 621), which lists species (without description) for the Chusovaya River with reference to Lepechin (1771: 491). Lepechin gives a description of the species but does not give the species name, designated as “ CYPRINVS ” with the type locality “ circa Catharinopolin ” (now Yekaterinburg). Although Georgi does not provide a description of species when mentioning the name isetensis , he makes a reference to the description of this species in Lepechin’s study, which makes this name valid since it complies with Art. 12.1 and 12.2 of the International Code of Zoological Nomenclature ( ICZN 1999).

Type locality.

The type locality from the original description ( Lepechin 1771: 493) is “ … habitat in rivis scopulosus circa Catharinopolin, ” which means “ … lives in the rocky streams around Catharinopolin (now Yekaterinburg). ” Probably Lepechin meant the upper reaches of the Iset, Chusovaya, and Tura rivers, which were specified in further publication ( Lepechin 1772: 311).

Type locality for the neotype: Severka River (56.8830 ° N, 60.2716 ° E) upstream of Severka village near Yekaterinburg, Sverdlovsk Oblast, Russia (Fig. 6 ). A tributary of the Reshotka River → Iset River → Tobol River → Irtysh River → Ob River → Kara Sea.

Nomenclatural and taxonomic actions.

The need to designate a neotype for P. isetensis is determined by the following considerations: first, our attempts to find a type specimen at the Zoological Institute of the Russian Academy of Sciences, Saint Petersburg, Russia ( ZISP), where the largest and oldest ichthyological collection in Russia is stored, were unsuccessful. At the end of the 18 th century, at the time of the description of P. isetensis , it was the only scientific organization in Russia where type specimens were deposited. The type specimens of P. isetensis were absent in the ZISP already at the beginning of the 20 th century ( Berg 1912). Second, no type specimens for all the fish species described by the naturalist and explorer Johann Gottlieb Georgi (1729–1802) were designated ( Fricke et al. 2024). Thus, we conclude that Georgi did not designate a type series for this species. Third, in addition to P. isetensis , at least one more species of this genus inhabits the Ob River basin — P. ujmonensis Kashchenko, 1899 (see Discussion), and their possible sympatric co-occurrence requires further clarification.

Thus, based on the above-mentioned circumstances and in accordance with Article 75 of the ICZN, we designate a neotype for P. isetensis . Our nomenclatural actions do not contradict the statements of Article 75.3 (qualifying conditions), and the designation of a nomenclatural type (neotype) for P. isetensis , as a widespread species living in Europe and Asia, will make it possible to clearly describe both morphological and genetic differences from other species of the genus Phoxinus (Articles 75.3. 1 and 75.3. 2).

Distribution and habitat.

Widespread in northern and eastern Europe and in the western edge of Siberia (Iset and partially Ural basin). Phoxinus isetensis inhabits the basins of the Caspian, Baltic, White, Barents, and Kara seas, possibly occurring in the North Sea basin. In the Caspian Sea basin, it is widely distributed in the upper and middle Volga, Kama, in the mountainous part of the Ural basin. In the Baltic Sea basin, it is widespread in the northern and eastern parts. In the Kara Sea basin, it is known in the Iset basin (Ob basin). According to Palandačić et al. (2017, 2020), mtDNA of this species (Clade 17) was detected in Scandinavia and the British Isles, suggesting that minnows from these areas also belong to the species P. isetensis .

Dyldin et al. (2023: 671) pointed out the distributional range of P. isetensis as “ Arctic Ocean basin, from Murman coast to East Siberian Sea basin (Kolyma basin); rivers of northern and western Sea of Okhotsk basin (Ola and Uda rivers); rivers of Peter the Great Bay drainage, probably Amur River basin, and northwestern Sakhalin Island. ” This data only partially corresponds to the above-mentioned range. See further explanations in the discussion.

Phoxinus isetensis prefers rivers with fast-flowing water that are rheophilic. In the northern regions, it also inhabits riverbeds of large rivers, lakes, and brackish waters ( Berg 1949: 590; Tsvelev 2007: 277; our data).

Morphology comparison.

PCA of 41 morphometric characters shows differences between P. isetensis and P. adagumicus , P. chrysoprasius , and P. colchicus from the Crimean Peninsula and the Caucasus (Fig. 7 ). The greatest difference is from P. colchicus (no overlap), while the remarkable overlap with the other two species ( P. adagumicus and P. chrysoprasius ) is noted.

Compared to P. abanticus from the Lake Abant basin in Türkiye ( Turan et al. 2023), P. isetensis has scales on the breasts in both sexes (vs. absence of scales on the breast in males); 18–20 rays in the caudal fin (vs. 15–16 rays); and a more slender caudal peduncle (6.6–9.5, mean 8.0 vs. 11.0–12.7, mean 12.0).

Compared to P. adagumicus from the Kuban basin ( Artaev et al. 2024), P. isetensis has fewer scale rows above the lateral line (10–21, mean 15.1, vs. 15–24, mean 18.4); more total vertebrae (39–43, mean 41.0, mode 41, vs. 39–42, mean 40.4, mode 40); more caudal vertebrae (16–21, mean 18.9, mode 19, vs. 16–19, mean 18.0, mode 18); double-row pharyngeal teeth with modal formula 2.5–4.2 (vs. single-row pharyngeal teeth with modal formula 5–4) (Suppl. material 4).

Compared to P. bigerri from the Adour and Ebro basins in France and Spain ( Kottelat 2007), P. isetensis has fewer scale rows above the lateral line (10–21, mean 15.1, vs. 19–23).

Compared to P. chrysoprasius from the rivers of the Crimean Peninsula ( Artaev et al. 2024; Bogutskaya et al. 2023), P. isetensis has a slightly selender caudal peduncle (minimum depth of caudal peduncle (6.6–9.0 % SL, mean 7.7 in females and 7.2–9.5, mean 8.2 in males (vs. 8.4–9.9, mean 9.1 in females and 8.1–11, mean 9.9 in males); slightly fewer circumpeduncular scales – 28–45, mean 35.3 (vs. 41–55, mean 46.2); more total number of vertebrae – 39–43, mean 41.0, mode 41 (vs. 38–42, mean 40.4, mode 40); more number of caudal vertebrae – 16–21, mean 18.9, mode 19 (vs. 16–20, mean 18.0, mode 18) (Suppl. material 4).

Compared to P. colchicus from the Black Sea coast of the Caucasus and Kuban basin ( Artaev et al. 2024; Bogutskaya et al. 2023), P. isetensis in both sexes have a slenderer caudal peduncle (minimum depth of caudal peduncle in percentage of caudal peduncle length 26.9–40.6, mean 32.5; vs. 42.0–58.6, mean 49.5); (Suppl. material 3); less number of circumpeduncular scales – 28–45, mean 35.3 (vs. 36–48, mean 40.9); less number of scales above lateral line – 10–21, mean 15.1 (vs. 16–23, mean 18.8); fewer scale rows below lateral line – 8–16, mean 11.2 (vs. 11–17, mean 13.4); different patterns of scalation on the breast and anterior belly – 3 rd – 6 th types, mode 4 th (vs. 3 rd – 10 th, 13 th and 14 th, modal 6 th); more total number of vertebrae – 39–43, mean 41.0, mode 41 (vs. 39–42, mean 40.1, mode 40); more number of caudal vertebrae – 16–21, mean 18.9, mode 19 (vs. 16–19, mean 17.6, mode 18) (Suppl. material 4).

Compared to P. csikii from the Danube River basin, Montenegro, and Bulgaria ( Bogutskaya et al. 2019, 2023), P. isetensis has a different pattern of scalation on the breast and anterior belly – 3 rd – 6 th types, mode 4 th (vs. 3 rd – 9 th types, 11 th, mode 7 th); more total number of vertebrae – 39–43, mean 41.0, mode 41 (vs. 38–42, mean 40.1, mode 40); more number of caudal vertebrae – 16–21, mean 18.9, mode 19 (vs. 15–19, mean 17.4, mode 17); smaller difference between numbers of abdominal and caudal vertebrae – 0–7, mean 3.2 (vs. 2–9, mean 5.4) (Suppl. material 4).

Compared to P. krkae from the Krka River, Croatia ( Bogutskaya et al. 2019), P. isetensis has a greater number of lateral-line scales (pored) 12–94, mean 53.7 (vs. 11–54, mean 32.6); different pattern of scalation on the breast and anterior belly – 3 rd – 6 th types, mode 4 th (vs. 3 rd – 7 th types, mode 6 th); more total number of vertebrae – 39–43, mean 41.0, mode 41 (vs. 37–40, mean 38.4, mode 39); more number of caudal vertebrae – 16–21, mean 18.9, mode 19 (vs. 15–18, mean 16.8, mode 17) (Suppl. material 4).

Compared to P. lumaireul Clades 1 a and 1 b from rivers in Adriatic and Black Sea basins in Italy, Slovenia, and Croatia ( Bogutskaya et al. 2019), P. isetensis has a different pattern of scalation on the breast and anterior belly – 3 rd – 6 th types, mode 4 th (vs. 2 nd – 7 th types, mode 3 rd); more total number of vertebrae – 39–43, mean 41.0, mode 41 (vs. 37–41, mean 39.3, mode 39); more number of caudal vertebrae – 16–21, mean 18.9, mode 19 (vs. 16–19, mean 17.5, mode 18) (Suppl. material 4).

Compared to P. marsilii from the Danube River basin, Austria, and Croatia ( Bogutskaya et al. 2019, 2023), P. isetensis has a different pattern of scalation on the breast and anterior belly – 3 rd – 6 th types, mode 4 th (vs. 3 rd – 8 th types, mode 6 th); more total number of vertebrae – 39–43, mean 41.0, mode 41 (vs. 38–42, mean 40.1, mode 40) (Suppl. material 4).

Compared to P. radeki from the Ergene River (Aegean Sea basin) in Türkiye ( Bayçelebi et al. 2024), P. isetensis has a higher number of scales above the lateral line- 10–21 (vs. 9–15) and below the lateral line – 8–16 (vs. 6–9).

Compared to P. septimaniae from the Herault River, France ( Bogutskaya et al. 2019), P. isetensis has a different pattern of scalation on the breast and anterior belly – 3 rd – 6 th types, mode 4 th (vs. 12 th – 14 th types, mode 14 th); a greater total number of vertebrae – 39–43, mean 41.0, mode 41 (vs. 37–41, mean 39.3, mode 39); a greater number of caudal vertebrae – 16–21, mean 18.9, mode 19 (vs. 16–19, 21, mean 17.6, mode 18) (Suppl. material 4).

Compared to P. strandjae from the rivers of the Black Sea basin, Bulgaria, and the rivers of the Marmara Sea, Türkiye ( Bogutskaya et al. 2019, 2023), P. isetensis has a different pattern of scalation on the breast and anterior belly – 3 rd – 6 th types, mode 4 th (vs. 3 rd – 12 th types, mode 11 th); a greater total number of vertebrae – 39–43, mean 41.0, mode 41 (vs. 38–42, mean 39.8, modal 40); a greater number of caudal vertebrae – 16–21, mean 18.9, mode 19 (vs. 16–19, mean 17.7, mode 18) (Suppl. material 4).

Compared to P. strymonicus from the Strymon basin in Greece and Macedonia (Kottelat, 2007), P. isetensis has a smaller number of scales above the lateral line: 10–21 (vs. 21–24).

Compared to P. cf. ujmonensis from the Mundybash River in Altai part of the Ob basin (Suppl. material 4), P. isetensis has a smaller number of scales above the lateral line: 10–21, mean 15.1 (vs. 15–19, mean 17.3); and a number of scales below the lateral line: 8–16, mean 11.2 (vs. 12–15, mean 12.9).

Figures

Figure 3. Neotype of Phoxinus isetensis (SL 63.9 mm, IBIW _ FS _ 422, female). A. Live appearance; B. General appearance of the preserved specimen; C. Radiograph.

Figure 4. Live appearance of Phoxinus isetensis from different basins. A. Male in pre-spawning coloration, SL 48.5 mm, Nataleyka R. (Middle Volga basin), 53.9781 ° N, 45.6530 ° E, 05 May 2022; B. Female in pre-spawning coloration, SL 48.8 mm, same location and date; C. Female, SL 64.3 mm, Okhomlya R. (Baltic Sea basin), 58.7078 ° N, 33.5199 ° E, 12 September 2021; D. Female, SL 62.4 mm, Kyltymyu River (Northern Dvina basin), 61.4981 ° N, 50.5831 ° E, 21 September 2022; E. Male, SL 59.5 mm, Marat Bai River (Ural basin), 54.0668 ° N, 58.8038 ° E, 4 June 2023; F. Female, SL 63.6 mm, Karnasyavryok River (Barents Sea basin), 68.9314 ° N, 34.9318 ° E, 27 May 2023.

Figure 5. Morphological features of Phoxinus isetensis. A. Most frequent variant of the formula of pharyngeal bones: double-rowed formula 2.5–4.2, scale bar 0.5 mm; B. Ventral view of alizarin-stained female and male from the Bekshanka River (Volga basin). Female had 5 th type scalation on breast and belly, male had 6 th type.

Figure 6. Example of habitat in the Severka River, type locality for Phoxinus isetensis, 21 June 2023.

Figure 7. PCA based on 41 morphometric characters for Phoxinus spp. – P. isetensis, P. chrysoprasius from the Crimean Peninsula, P. colchicus, and P. adagumicus from the Caucasus – and loading plot showing how strongly each character influences principal components. Samples of P. isetensis from the type locality (Severka River) are encircled by black.