Salmo araxensis, Turan & Kottelat & Kaya, 2022

Turan, Davut, Kottelat, Maurice & Kaya, Cüneyt, 2022, The trouts of the upper Kura and Aras rivers in Turkey, with description of three new species (Teleostei: Salmonidae), Zootaxa 5150 (1), pp. 43-64 : 51-53

Salmo araxensis , new species

( Figs. 5–6 )

Salmo trutta macrostigma (non Duméril, 1858): Aras, 1974: 73–76 (Aras River).

Salmo trutta caspius (non Kessler, 1877): Tortonese, 1955: 11 (Aras River)

Holotype. FFR 3224, 259 mm SL; Turkey: Kars Prov.: Susuz district: Kırkpınar Stream, a tributary of Kars Stream , Aras River drainage (40°51’N 43°01’E); D. Turan & S. Engin, 3 September 2006.

Paratypes. FFR 3122, 6, 140–250 mm SL; CMK 19739, 2, 133–172 mm SL; same data as holotype.—FFR 3114, 12, 116–201 mm SL; Kars Prov.: Susuz district: Kayalık Stream, a tributary of Kars Stream (40°49’N 43°07’E), Aras River drainage; D. Turan & S. Engin, 3 September 2006 .— FFR 3115, 15, 93–237 mm SL; CMK 19462, 3, 117–162 mm SL; Kars Prov.: Susuz district: Porsuklu (Akçalı) Stream , a tributary of Kars Stream (40°48’N 43°11’E), Aras River drainage; D. Turan & S. Engin, 5 July 2006 .— FFR 3118, 6, 95–132 mm SL; Kars Prov.: Sarıkamış district: Boyalı Stream, a tributary of Kars Stream (40°26’N 42°34’E), Aras River drainage; D. Turan & S. Engin, 5 July 2006 .— FFR 3144, 16, 87–265 mm SL; Turkey: Kars Prov.: Susuz district: İncilipınar Stream, a tributary of Kars Stream (40°49’N 43°04’E), Aras River drainage; D. Turan, C. Kaya & E. Baycelebi, 15 July 2012 .

Diagnosis. Salmo araxensis is distinguished from all the species of Salmo in adjacent waters by a combination of the following characters: body greyish to brownish in life; commonly one black spot behind eye, faintly marked; 3–10 black spots on preopercle and opercle; black spots on body few (7–27), scattered on back and upper part of flank, ocellated with a roundish narrow white ring; red spots few (30–39), small (about half of pupil diameter), faintly marked, ocellated, surrounded by a narrow white ring in males and females, usually organized in 2–4 irregular longitudinal rows on median and lower part of flank; maxilla length 9–10% SL in males, 8–9 in females, reaching slightly beyond eye in males larger than about 130 mm SL and in females larger than about 190 mm SL; 103–114 lateral-line scales; 27–28 scale rows between lateral line and dorsal-fin origin; 17–20 scale rows between lateral line and anal-fin origin; 13–16 scale rows between lateral line and end of base of adipose fin; gill rakers 21–22 on outer side of first gill arch; 10–13 parr marks on flank, visible in specimens up to about 130 mm SL. No dark band on flank.

Description. General appearance is shown in Figs. 5–6 . Morphometric and meristic data are given in Tables 2–3 . Body somewhat deep, slightly compressed laterally. Dorsal profile arched in males, straight or slightly arched in females, ventral profile less arched than dorsal profile in males and females. Head short, its length 24–29% SL in males, 23–28 in females, upper profile convex in interorbital area and slightly concave at level of nostrils in males, markedly convex in interorbital area and snout in females. Mouth small, length of gape 12–16% SL in males, 12–15 in females, slightly subterminal in males and females. Maxilla short, its length 9–10% SL in males, 8–9 in females, reaching beyond eye in males larger than about 150 mm SL and in females larger than about 210 mm SL. Snout short, its length 6–8% SL in males, 6–7 in females, with pointed tip in males and slightly pointed in females. Adipose fin somewhat large, its height 6–10% SL in males, 6–8 in females. Vomer teeth small, in two rows.

Lateral line with 103–114 scales; 24–28 scale rows between lateral line and dorsal-fin origin; 17–20 scale rows between lateral line and anal-fin origin; 13–16 scale rows between lateral line and end of base of adipose fin. Dorsal fin with 3–4 simple and 9–11 branched rays; distal margin straight. Pectoral fin with 1 simple and 10–12 branched rays; outer margin convex. Pelvic fin with 1 simple and 7–8 branched rays; outer margin convex. Anal fin with 3 simple and 7–8 branched rays; distal margin slightly convex anteriorly and concave posteriorly. Caudal-fin slightly forked, upper lope pointed and lower lobe rounded. Gill rakers 8–10 + 11–13 = 21–22 on outer side of first gill arch.

Sexual dimorphism. Males of S. araxensis have a slightly longer head than females (24–29% SL, mean 27.2 vs. 23–28, mean 25.8), a slightly deeper body (22–27% SL, mean 25.0 vs. 21–26, mean 23.6), a slightly longer snout (6–8% SL, mean 7.1 vs. 6–7, mean 6.3), a longer maxilla (9–10% SL, mean 9.3 vs. 8–9, mean 8.6) and a somewhat greater mouth gape (9–11% SL, mean 9.7 vs. 8–10, mean 8.7) than females.

Coloration. In live and preserved specimens, body greyish to brownish on back and flank, belly yellowish. Commonly one black spot behind eye, faintly marked; 3–10 black spots on preopercle and opercle. No or 1–3 black spots on top of head. Black spots on body few (23–27 in males, 7–24 in females), small (usually smaller than pupil), ocellated, surrounded by a narrow white ring, restricted to back (but usually missing medially in predorsal area) and to upper part of flank. Red spots few (27–51), small (smaller than pupil), not conspicuous, ocellated, surrounded by a narrow white ring, usually organized in two to four irregular longitudinal rows on median and lower part of flank. Dorsal fin dark grey, with one or two rows of red spots and 2–5 rows of black spots, slightly marked. Caudal fin dark grey; pectoral, pelvic and anal fins greyish or yellowish; adipose fin dark grey, with no or one red spot along free edge. 10–13 parr marks on flank, visible in specimens up to about 130 mm SL, commonly vertically elongated.

Distribution and notes on biology. Salmo araxensis is only known from three tributaries of Kars Stream (Kırkpınar, Porsuklu and İncilipınar streams), in Aras River drainage ( Fig. 3 ). During various surveys in the area, S. araxensis has been observed neither in the lower part of the streams, nor in the other tributaries of Aras River, therefore, we consider that the species is not anadromous and is restricted to these streams. It inhabits headwaters, with clear and swift flowing water, with stone and pebble bottom. Its maximum known size is 276 mm SL. Mature individuals were observed in both sexes.

Etymology. The name araxensis is derived from Arax, the ancient name of the Aras River. An adjective.

Figures

FIGURE 3. Map of eastern Anatolia showing the distribution of the native Salmo specimens examined for this study.

FIGURE 5. Salmo araxensis; Turkey: Kars Prov.: Kırkpınar Stream; a, FFR 3224, holotype, 259 mm SL, male; b, FFR 3122, paratype, 220 mm SL, female; c, FFR 3122, paratype, 145 mm SL, juvenile.

FIGURE 6. Salmo araxensis; FFR 3144, paratype, 265 mm SL, male; Turkey: Kars Prov.: İncilipınar Stream.