Phoxinus radeki, Bayçelebi & Aksu & Turan, 2024

Baycelebi, Esra, Aksu, Ismail & Turan, Davut, 2024, Description of a new species of Phoxinus from the Ergene River (Aegean Sea Basin) in Tuerkiye (Actinopterygii, Leuciscidae), Zoosystematics and Evolution 100 (1), pp. 101-110 : 101

Phoxinus radeki sp. nov.

Figs 2 , 3 , 4

Materials examined.

Holotype. FFR 2327, 54 mm SL; Türkiye: Kirklareli prov. : stream Büyükdere about 6 km west of Pınarhisar, 41.6337, 27.5994.

Paratypes. FFR 2301, 12, 45-71 mm SL. -FFR 2304, 20, 42-68 mm SL; -FFR 2314, 19, 38-46 mm SL; same data as holotype. -FFR 2320, 22, 44-60 mm SL; Türkiye: Kirklareli prov. : stream Poyralı about 5 km west of Pınarhisar, 41.6172, 27.5909 . - FFR 2311, 1, 49 mm SL; Türkiye: Kirklareli prov. : stream Ahmetbey at Soğurcak, 41.6345, 27.6540 . - FFR 2326, 26, 44-65 mm SL; Türkiye: Tekirdag prov. : Ergene River at Saray, 41.4257, 27.9131 .

Genetic material.

FFR-DNA-Ph42-43-44-45-46; Türkiye: Kirklareli prov. : stream Büyükdere about 6 km west of Pınarhisar, 41.6337, 27.5994 (GenBank accession numbers: OR552425-OR552426-OR552427-OR552428-OR552429). -FFR-DNA-Ph31-32; Türkiye: Kırklareli prov.: stream Ahmetbey at Soğurcak, 41.6345, 27.6540 (GenBank accession numbers: OR552423-OR552424) .

Diagnosis.

Phoxinus radeki is distinguished from the Phoxinus species ( P. strandjae , P. abanticus ) in adjacent basins as below. It is immediately distinguished from species P. strandjae by body color and pattern (not spawning period and immediately after fixation). Phoxinus radeki has short dark rectangular blotches along the lateral line. The area between the lateral line and belly is yellowish in both males and females. There are irregularly-shaped black spots on the upper part of the flank and no dark stripes on the middle part of the flank in males. Phoxinus strandjae (Fig. 5 ) has bars reaching from the dorsal to below the lateral line, hyaline between the lateral line and belly in females, blackish in males and no black spots on the upper part of the flank. It further differs from P. strandjae by the scales of the breast. Phoxinus radeki has breast scaled but separated unscaled area anteriorly, P. strandjae has breast scaled connected or scales not connected anteriorly (Fig. 7 ).

Phoxinus radeki is distinguished from species P. abanticus by the presence of scales on the breast in males (vs. absent, Fig. 7 ), a slenderer body (body depth dorsal fin origin 16-21% SL vs. 22-25) and a slenderer caudal peduncle (8-10% SL vs. 11-13). It further differs from P. abanticus by having more lateral line scales (75-96 vs.60-69).

Description.

The general appearance is shown in Figs 2 - 4 , and morphometric data are given in Table 1 . The maximum size is 71 mm SL. Body depth at dorsal-fin origin 16%-21% SL.The dorsal body profile more convex than the ventral profile. The head short, its length 24%-27% SL, upper profile straight or slightly convex on the interorbital area and convex on the snout. The snout short and its upper profile markedly convex. The mouth terminal to slightly subterminal, the upper lip not projecting or slightly projecting beyond the tip of the lower lip. The corner of the mouth reaches to level with the lower margin of the eye or pupil.

Lateral line complete, with 75-96 scales, and almost reaching to caudal-fin base; 9-15 scale rows between lateral line and dorsal-fin origin; and 6-9 scale rows between lateral line and anal-fin origin. Dorsal fin with three simple 7½ branched rays, outer margin straight or slightly convex. Pectoral-fin with 16-18 rays, outer margin convex. Pelvic fin with seven to eight branched rays, outer margin convex. Anal fin with three simple 6½-7½ branched rays, outer margin straight or convex. The caudal fin, deeply forked.

Coloration (Not spawning period and immediately after fixation): A short dark rectangular blotch along the lateral line, between the lateral line and belly yellowish in both males and females, irregularly shaped black spots on the upper part of the flank and no dark stipe or very faintly marked narrow stripe on the middle part of flank in males. Dorsal and caudal fins slightly gray or hyaline, pectoral, pelvic and anal fins hyaline (except for some individuals). In some specimens often 10-14 short brownish bars over-imposed on the stripe. Black spot in the middle of the caudal-fin base.

Sexual dimorphism.

Males with stronger and longer pectoral fins, and nuptial tubercles on the head, in both species.

Etymology.

The species is named for Radek Sanda (Prague) for his contribution to the knowledge of the ichthyofaunal of Europe. A noun in genitive, indeclinable.

Distribution.

Phoxinus radeki is presently known from the Ergene River (Ageaen Sea Basin) (Fig. 1 ). It inhabits the cold, well-oxygenated waters of fast-flowing mountain streams and large lowland rivers. A transboundary river known as Meriç-Ergene (Maritsa, Evros) serves as a border between Türkiye, Greece, and Bulgaria. It starts in Bulgaria and flows through Türkiye, where it forms a 203 km-long border with Greece. It is the longest river in the Balkan Region. Before flowing into the Aegean Sea, the river passes through Greece. Bulgaria (upstream), Türkiye (downstream), and Greece (downstream) are the three riparian nations in the basin. The remaining 35% of its catchment area is divided into 28% and 7% within the borders of Türkiye and Greece, respectively, while the remaining 65% of its catchment area is contained within the boundaries of Bulgaria. The border between Türkiye and Greece is formed by a piece of the Meriç River’s lower course, while the remaining portion flows in Türkiye. The river emerges into the Aegean Sea from Saros. (https://floodmerg.tarimorman.gov.tr/en/meric-ergene-river-basin). It is known that after the entry of the Ergene River into the system, the water quality of the Meriç River decreased seriously and this situation adversely affected the biota ( Elipek et al. 2010; Güher et al. 2011; Tokatlı 2020).

Figures

Figure 1. Distribution of Phoxinus species in the Aegean and Black Sea basins and Abant Lake.

Figure 2. Phoxinus radeki FFR 2327: holotype, 54 mm SL, male; Tuerkiye: Ergene River.

Figure 3. Phoxinus radeki FFR 2326, from top: paratypes, 57 - 55 mm standard length (SL), possible males; Tuerkiye: Ergene River.

Figure 4. Phoxinus radeki FFR 2311, from top: paratypes, 46 mm SL, male; 55 mm SL female; Tuerkiye: Stream Ahmetbey.

Figure 5. Phoxinus strandjae FFR 2312, from top: 62 mm SL male; 62 mm SL female; Tuerkiye: Rezve River.

Figure 7. Breast scale shape of a. Phoxinus radeki, b. P. strandjae and c. P. abanticus.