Cobitis troasensis, Freyhof & Bayçelebi & Geiger, 2018

Freyhof, Jörg, Bayçelebi, Esra & Geiger, Matthias, 2018, Review of the genus Cobitis in the Middle East, with the description of eight new species (Teleostei: Cobitidae), Zootaxa 4535 (1), pp. 1-75 : 65-67

Cobitis troasensis , new species

( Fig. 51–53 )

Holotype. ZFMK ICH-098603 , 50 mm SL; Turkey: Çanakkale prov.: stream Tuzla about 1 km south of Ayvacık , 39.596 26.438.

Paratypes. FSJF 2383 , 8 , 43–76 mm SL; same data as holotype—FSJF 2317, 2, 59–60 mm SL; Turkey: Çanakkale prov.: stream Tuzla about 1 km north of Behramkale, 39.498 26.333.—FFR 0 5529, 1, 65 mm SL; Turkey: Çanakkale prov.: stream Tuzla about 1 km south of Ayvacık , 39.586 26.417 .

Material used in molecular genetic analysis. None

Diagnosis. Cobitis troasensis is distinguished from C. fahireae by having 11–15 small, irregularly commashaped blotches in Z4 anterior to the dorsal-fin origin (vs. 6–8 large, roundish, triangular, squarish, or horizontally elongate, often very densely set and fused to each other). In C. troasensis , the blotches in Z2 are usually fused into a stripe reaching to the vertical or the anus, fused with the pigmentation in Z1 and Z3 on the caudal peduncle into a mottled pattern (vs. blotches in Z2 usually well separate) and the black spot at the upper caudal-fin base is small and usually roundish (vs. absent in many populations of C. fahireae ).

Cobitis troasensis is distinguished from C. emrei , C. elongatoides , C. pontica , C. splendens and C. tanaitica by having 11–15 small, comma-shaped blotches in Z4 along the flank anterior to the dorsal-fin origin (vs. 5–7 horizontally elongate, often very densely set and fused into short or longer stripes in C. emrei , well separate and irregularly roundish or squarish in C. splendens , vertically elongate or roundish and well separated in C. elongatoides , C. pontica and C. tanaitica ) and the black spot at the upper caudal-fin base smaller or equal to the eye diameter (vs. larger than the eye diameter in C. elongatoides , C. pontica , C. emrei , C. splendens and C. tanaitica ).

Cobitis troasensis is further distinguished from C. emrei by having a more slender body (body width 8–9% SL vs. 9–11 in the male; 7–10% SL vs. 10–12 in the female) and a greater head length in the male (21% SL vs. 21–24). It is further distinguished from C. splendens and C. tanaitica by the pigmentation in Z3 reaching to the caudal peduncle in the male (vs. Z3 reduced to about head length in C. splendens , Z3 usually reaching to the dorsal-fin base in C. tanaitica ) and Z3 wider than Z 2 in the male (vs. usually Z3 narrower than Z2). Cobitis troasensis is distinguished from C. puncticulata by lacking the pigmentation on the flank below Z4 (vs. pigmented) and having a pale yellowish or whitish background coloration (vs. brownish).

Cobitis troasensis is distinguished from C. afifeae , C. dorademiri , C. phrygica and C. strumicae by having one laminae circularis in the males (vs. two).

Description. See Figures 51–53 for general appearance and Table 9 for morphometric data of the holotype and 11 paratypes. Greatest body depth at or slightly anterior to dorsal-fin origin, decreasing towards caudal-fin base. Head profile slightly convex, head length 1.0–1.4 times in body depth. Snout pointed, its length 0.6–0.9 times in postorbital length. Eye diameter 0.2–0.4 times in head depth at eye, 1.3–2.7 times in interorbital width. Caudal peduncle 1.2–1.7 times longer than deep. Pelvic axillary lobe present. Margin of dorsal and anal fins convex. Caudal fin truncate. Very shallow ventral keel on caudal peduncle. External part of the suborbital spine bifurcate, reaching slightly beyond centre of eye. Largest recorded specimen 76 mm SL.

Dorsal fin with 3 unbranched and 6½ (12) branched rays. Anal fin with 3 unbranched and 5½ (11) and 6½ (1) branched rays. Caudal fin with 7+7 branched rays in the 5 males and 4 females, 7+ 8 in the 2 females and 8+ 8 in the one female. Pectoral fin with 7 (4) and 8 (8) branched rays and pelvic fin with 5 (1) and 6 (11) branched rays. Body completely covered by embedded scales, except on belly and breast. Scales small. Focal area in subdorsal scales about 1/2 or 1/3 of vertical scale diameter. Lateral line short, with 4–6, pores reaching to anterior part of pectoral fin. Lips ( Fig. 54 ) thin, mental lobes of lower lip short, usually well separated, not produced into a barbel-like process. Rostral barbel reaching base of mandibular barbel. Mandibular barbel reaching to or slightly beyond vertical of nostril. Maxillary barbel reaching vertical of front border or middle of eye.

Sexual dimorphism. Males have a longer pectoral fin (18–24% SL vs. 14–16) and one lamina circularis (vs. absent).

Colouration. Body whitish with a dark-brown pigmentation pattern organised in one mid-dorsal and four lateral zones. Mid-dorsal pigmentation consists of a series of 16–20 roundish blotches in few and a marbled pattern on mid-dorsal back in most individuals. Many, very small spots in Z1, Z1 as wide as or wider than Z2, pigmentation not reaching dorsally to interspaces of mid-dorsal blotches, reaching to dorsal-fin base, pigmentation in Z1 fused with pigmentation in Z2 and Z3 on postdorsal flank. Spots in Z2 of about ½–1 pupil size, very densely set, usually fused into a stripe anterior to dorsal-fin base. Pigmentation in Z2 reaching to anus in some individuals, reaching to caudal peduncle in other individuals. Few, very small spots in Z3 along predorsal flank in most male, many small spots in female, Z3 much wider than Z 2. 11–15 predorsal, 3–4 subdorsal and 10–17 postdorsal blotches in Z4, blotches small, irregularly comma-shaped anterior to anal-fin origin, larger, more squarish or roundish on caudal peduncle. A single black spot at upper caudal-fin base, distinct, smaller than eye size. Upper part of head, opercle and snout covered by small spots. A dark-brown stripe between eye and snout. Fins hyaline. Caudal fin with 4–8 and dorsal fin with 4–5 dark, sometimes irregular shaped bars. No pigmentation on paired fins. Barbels whitish.

Etymology. Named for Alexandria Troas, an ancient Greek city located southeast of the modern village Dalyan in the Çanakkale Province. An adjective.

Distribution. Known only from the Tuzla River. The Tuzla River is flowing to the northernmost Aegean Sea in Turkey, just at the entrance of the Dardanelles.

Remarks. No molecular data are available from C. troasensis but we expect this species to belong to the C. taenia species group, as it has only one scale-shaped lamina canestini in the male (vs. two in other species groups in the area). Cobitis troasensis might be endemic to the Tuzla River. Tuzla River is also inhabited by Squalius aristotelis , a second species described as being endemic to the Tuzla River by Özuluğ & Freyhof (2011). Future studies should investigate the fish fauna of Tuzla River and adjacent rivers more in detail not only to better understand the biogeographic relationships of fish species inhabiting this river, but also to find out, if C. troasensis (and S. aristotelis ) are indeed endemic to this small area.

Figures

FIGURE 51. Cobitis troasensis, left column from the top: males, ZFMK ICH-098603, holotype, 50 mm SL; paratypes, FSJF 2383, 47 mm SL, 43 mm SL; right column from the top: females, 76 mm SL, 72 mm SL, 55 mm SL; Turkey: stream Tuzla.

FIGURE 52. Cobitis troasensis, left column from the top: males, ZFMK ICH-098603, holotype, 50 mm SL; paratypes, FSJF 2383, 47 mm SL, 43 mm SL; right column from the top: females, 76 mm SL, 72 mm SL, 55 mm SL; Turkey: stream Tuzla.

FIGURE 53. Cobitis troasensis, FSJF 2317, male, 60 mm SL; Turkey: stream Tuzla.

FIGURE 54. Upper row: Cobitis afifeae, FSJF 3022, paratype, 76 mm SL; Turkey: Büyük Menderes River; C. aliyeae, FSJF 2427, paratype, female, 65 mm SL; Turkey: Seyhan River; C. anabelae, ZFMK ICH-98633, holotype, male, 53 mm SL; Turkey: Karasu River; C. emrei, FSJF 1960, paratype, female, 77 mm SL; Turkey: Lake Sapanca basin; Lower row: C. erkakanae, FSJF 2510, paratype, female, 68 mm SL; Turkey: canal at Lake Gölbaşı; C. joergbohleni, ZFMK ICH-97624, holotype, female, 60 mm SL; Turkey: spring Soysallı; C. pirii, FSJF 2474, paratype, female, 95 mm SL; Turkey: streams Çayköy; C. troasensis, FSJF 2383, paratype, female, 72 mm SL; Turkey: stream Tuzla.