Gobio sakaryaensis, Turan, Davut, Ekmekçi, Güler, Luskova, Vera & Mendel, Jan, 2012

Turan, Davut, Ekmekçi, Güler, Luskova, Vera & Mendel, Jan, 2012, Description of a new species of genus Gobio from Turkey (Teleostei: Cyprinidae), Zootaxa 3257, pp. 56-65 : 57-61

Gobio sakaryaensis , new species

( Fig. 1 )

Gobio gobio (Linnaeus, 1758) : Kuru 1980: 26 (Sakarya River)

Gobio gobio (Linnaeus, 1758) : Erkakan, 1983: 28 (Sakarya River)

Gobio cf. caucasicus Kamensky, 1901 : Naseka et al. 2006: 189 (Sakarya River)

Holotype: FFR 2504, 82 mm SL, male, Turkey: Bilecik Prov.: Tozman Stream, 40º 04’ N 30º 30’E, Black Sea Basin, F. Güler Ekmekçi, & Mehmet Ekmekçi, 20 October 2006.

Paratypes: FFR 2505, 10, 49–89 mm SL, male, 4, 73– 88 mm SL, female; same data as holotype.

Additional material: IUSHM 2010-1000, 4, 73–115 mm SL, Turkey: Eskişehir Prov.: Pürtek Stream, 39º 33’ N 31º 45’E, Sakarya River, M. Özuluġ, & J. Freyhof, 16 June 2006. - IUSHM 2010-1001, 5, 72–93 mm SL, Turkey: Eskişehir Prov.: Porsuk Stream, 39º 40’ N 30º 09’E, Sakarya River, M. Özuluġ & J. Freyhof, 16 June 2006.

Diagnosis. Gobio sakaryaensis is distinguished from all other species of Gobio in Turkey by a combination of the following characters: breast completely scaled, scales approximately extending to isthmus ( Fig. 2 ); head length 27.2–30.0 % SL; snout shorter than postorbital distance; upper profile of head convex behind the nostril level, markedly concave at the nostrils, with rounded tip; reaching posterior margin of eye in male, reaching at midpoint of eye in female; interorbital distance 1.4–1.6 times eye diameter; body depth 21.5–24.4 % SL; pectoral fins reaching to or 1 scale anterior to pelvic-fin origin in males, 2 or 3 scales anterior to pelvic-fin origin in female; 39–42 lateral line scales; 4–6 scales between anus and anal fin origin; 6–8 scales between posterior extremity of pelvic-fin bases; 8–9 midlateral blotches; 10–14 slightly marked blotches on dorsal; intense black pigments on flank and back scales.

Description. General appearance is shown in Figure 1 ; morphometric and meristic data are given in Tables 1 and 2. Body deep, slightly compressed laterally; depth at dorsal fin origin 21.5–24.4 % SL. Predorsal profile markedly convex, postdorsal profile slightly concave, ventral profile straight between isthmus and anal-fin origin. Head long, its length 27.2–30.0 % SL; dorsal profile slightly convex at interorbital area, convex in front of the nostrils, markedly concave at nostril level. Snout length 10.2–11.6 % SL; snout tip rounded, with a prominence forward of nostril level. Mouth large, horseshoe-shaped. Lower jaw length approximately equal to its width. In males barbel reaches almost to posterior margin of eye, in females, reaching at midpoint of eye. Eye diameter 5.4–6.9 % SL. Interorbital width 7.5–8.6 % SL, 1.4–1.6 times eye diameter. Largest individual is 89 mm SL.

Dorsal fin with 3 simple and 7½ branched rays, its height approximately equal to pectoral-fin length in males, distal margin slightly concave, its origin 1 scale in front of vertical through pelvic-fin origin in both sex. Pectoral fin long, its length 23.3–27.0 % SL in males, 21.8–24.5 in females, almost reaching pelvic fin origin in males, not reaching in females, distal margin straight or slightly concave, with 13–15 branched rays. Pelvic-fin, reaching behind anus in male and female, distal margin slightly rounded, with 8 branched rays. Anal fin with 3 simple and 6½ branched rays, distal margin straight or slightly concave. Caudal fin long, length of upper lobe 20.3–27.6 % SL, markedly forked, lobes slightly rounded. Lateral line with 39 (1), 40 (6), 41 (4) or 42 (4) scales; 6 (10) or 7 (5) scales rows between lateral line and dorsal-fin origin; 4 (2) or 5 (13) scales between lateral line and anal-fin origin; 6 (2), 7 (10) or 8 (3) scales between posterior extremity of pelvic fin base; 4 (6), 5 (7) or 6 (2) scales between anus and anal-fin origin. Gill rakers 2–3+1–2=3–5 on outer side of first gill arch. Pharyngeal teeth 5.3–3.5, slightly hooked.

Sexual dimorphism. The pectoral fins are longer in males than in females, its length 23.3–27.0 % SL in males, 21.8–24.5 in females. Barbels reaching posterior margin of eye in male, reaching at midpoint of eye in female.

Colouration. Formalin preserved adults and juveniles dark brown on back and flank, whitish on belly, 8–9 midlateral black blotches, and blotches not separated from one another, especially in specimens larger than 70 mm SL. 10–14 blotches on dorsal and upper part of flank. Highly dense black pigment on flank scales; dorsal, pectoral, pelvic and anal fins yellowish with small black spots.

Distribution and notes on biology. Gobio sakaryaensis is known from the Tozman Stream and Sakarya River ( Fig. 3 ). It inhabits a slow-flowing, seasonal stream disappearing into the Tozman sinkhole, and has no connection with any other surface water. Today the Tozman Stream has no connection with the main river. Despite this apparent geographic isolation, Gobio sakaryaensis is also present in the Sakarya River.

Etymology. The name of the species is derived from the Sakarya River.

Figures

FIGURE 1. Gobio sakaryaensis, holotype, FFR 2504, 82 mm SL, male; Turkey: Tozman Stream, Black Sea basin.

FIGURE 2. Ventral view of Gobio sakaryaensis, holotype.

FIGURE 3. Distribution of the Gobio species in Turkey.