Oxynoemacheilus muefiti, Freyhof & Kaya & Turan & Geiger, 2019

Freyhof, Jörg, Kaya, Cüneyt, Turan, Davut & Geiger, Matthias, 2019, Review of the Oxynoemacheilus tigris group with the description of two new species from the Euphrates drainage (Teleostei: Nemacheilidae), Zootaxa 4612 (1), pp. 29-57 : 48-52

Oxynoemacheilus muefiti , new species

( Figs 15–17 )

Holotype. FFR 15532, 70 mm SL, Ağrı prov.: Turkey: Murat River at Ballıbostan; 39.678 43.189.

Paratypes. FFR 15507, 2, 29–45 mm SL, same data as holotype.—FFR 1432, 7, 42–63 mm SL, Ağrı prov.: Turkey: Murat River at Taşlıçay; 39.646 43.367 .

Additional material. FSJF 3444 , 4 , 33–46 mm SL; Turkey: Ağrı prov.: Murat River at Ballıbostan , 12 km east of Ağrı, 39.6789 43.1896 .— FSJF 2556 , 3 , 45–47 mm SL; Turkey: Adıyaman prov.: stream Eğri south of Adıyaman, tributary to Atatürk reservoir, 37.7417 38.3351 .— IUSHM 2019-1410 , 3 , 37–68 mm SL; Turkey: Ağrı prov.: stream near Sarıköy, 16 km west of Eleşkirt , 39.8016 42.4816 .— IUSHM 2019-1411 , 3 , 43–52 mm SL; Turkey: Ağrı prov.: Murat River at Balıbostan , 12 km east of Ağrı, 39.6789 43.1896 .

Material used in molecular genetic analysis. FFR DNA- 330; Turkey: Ağrı prov.: Murat River at Ballıbostan, 12 km east of Ağrı, 39.6789 43.1896. ( GenBank accession numbers: MK 546505 ).— FSJF DNA-931 ; Turkey: Adıyaman prov.: stream Eğri km south of Adıyaman, tributary to Atatürk reservoir, 37.7417 38.3351. ( GenBank accession numbers: MK 546463 - MK 546465 ).— FSJF DNA-2366 ; Turkey: Ağrı prov.: Murat River at Ballıbostan, 12 km east of Ağrı, 39.6789 43.1896. ( GenBank accession number: MK 546466 ).— FSJF DNA-2380 ; Turkey: Ağrı prov.: stream near Sarıköy, 16 km west of Eleşkirt , 39.8016 42.4816. (GenBank accession number: MK 546467 ) .

Diagnosis. Oxynoemacheilus muefiti is distinguished from O. arsaniasus by lacking the central pore in the supratemporal canal (vs. present), having a mottled colour pattern on the caudal-fin base (vs. a bold bar, usually fused with a roundish or vertically elongate, dark-brown blotch at the vertical midline), a fine, brown, mottled colour pattern on the flank, usually organised in narrow, pale-brown bars on the flank behind the dorsal-fin base (vs. flank marmorate, often with a midlateral series of large, bold, dark-brown, very irregularly shaped blotches or short bars), the bars on the caudal peduncle not separated from the adjacent saddles on the back (vs. separated), and narrow, pale-brown, indistinct bands on the caudal fin (vs. usually bands wide, bold and dark-brown).

The new species is distinguished from O. ercisianus by having a longer and more slender caudal peduncle (caudal peduncle length 1.3–1.6 times its depth vs. 1.0–1.3) in individuals larger than 50 mm SL, a narrower body (body width at dorsal-fin origin 11–13% SL vs. 13–17), and a shallow dorsal adipose crest on the caudal peduncle reaching to the vertical through the base of the last anal-fin ray in individuals larger than 50 mm SL (vs. higher crest, not reaching to the vertical through the base of the last anal-fin ray base in individuals larger than 50 mm SL).

It is distinguished from O. hazarensis by lacking a suborbital groove in the male (vs. present), having no scales on the caudal peduncle (vs. with scales), a shorter outer rostral barbel (20–34% HL vs. 34–41), and shorter maxillary barbel (25–33% HL vs. 32–40). The new species is distinguished from O. kaynaki by having an incomplete lateral line (vs. complete), no pelvic axillary lobe (vs. present), no scales (vs. present), and no bold, black bar at the caudalfin origin (vs. present).

Oxynoemacheilus muefiti is distinguished from O. tigris by having a mottled flank pattern without bold bars (vs. 10–16 bold bars, very prominent on the caudal peduncle), no bold, black spots at the upper and lower caudal-fin base (vs. two bold, black spots in most individuals), and no scales (vs. present).

Oxynoemacheilus muefiti is further distinguished from the other species inhabiting the Euphrates drainage not belonging to the O. tigris species group by a combination of characters. It is distinguished from O. araxensis by lacking a suborbital groove in the male (vs. present), and lacking scales (vs. present). It is distinguished from O. argyrogramma , O. bergianus , O. euphraticus , and O. samanticus by having a slightly emarginated caudal-fin (vs. deeply emarginate or slightly forked), no suborbital groove in the male (vs. present), and no scales (vs. present), and no black spots at the caudal-fin base (vs. having two bold black jet spots in O. argyrogramma and O. euphraticus ). Oxynoemacheilus muefiti is distinguished from O. paucilepis by having an incomplete lateral line (vs. complete), and no scales (vs. flank covered by often isolated scales).

Description. See Figures 15–17 for general appearance and Table 3 for morphometric data. Medium-sized and stout species. Body deepest at about midline between nape and dorsal-fin origin, depth steeply decreasing at dorsal-fin base, slightly decreasing towards caudal-fin base. A shallow or well developed hump at nape. Greatest body width at pectoral-fin base. Section of head roundish, flattened on ventral surface, straight in interorbital space, convex on snout. Snout roundish. Caudal peduncle compressed laterally, 1.3–1.6 times longer than deep. No axillary lobe at base of pelvic fin. Pelvic-fin origin below third branched dorsal-fin ray. Anal-fin origin in front of vertical through middle between dorsal and caudal-fin origins. Pectoral fin reaching approximately 65–70% of distance from pectoral-fin origin to pelvic-fin origin. Pelvic fin not reaching vertical through tip of last dorsal-fin ray, not reaching to in front of anus. Anus about ½ eye diameter in front of anal-fin origin. Anal fin not reaching caudal-fin base. A shallow dorsal and ventral adipose crest on caudal peduncle. Dorsal adipose crest reaching to vertical through middle of caudal peduncle, not reaching to vertical through anal-fin base. Crests usually absent in individuals smaller than 50 mm SL. No central pore in supratemporal canal. Margin of dorsal fin straight or slightly convex. Caudal fin slightly emarginated. Largest known specimen 70 mm SL.

Dorsal fin with 8½ branched rays. Anal fin with 5½ branched rays. Caudal fin with 8+8 (n=6) and 9+8 (n=2) branched rays. Pectoral fin with 10 (n=3) and 11(n=5) and pelvic fin with 7 (n=7) and 8 (n=1) rays. No scales on back and flank. Lateral line incomplete, reaching to slightly in front of or behind vertical through dorsal-fin origin. Anterior nostril opening at end of a low, pointed and flap-like tube. Posterior tip of anterior nostril reaching to posterior nostril when folded backwards. No suborbital groove or flap in male. Mouth small, arched. Lips thick with large furrows. A short median interruption in lower lip. A shallow median incision in upper lip. Processus dentiformis wide and rounded. No median notch in lower jaw. Barbels short, inner rostral barbel not reaching to base of maxillary barbel; outer one reaching to vertical between posterior nare and anterior eye margin. Maxillary barbel reaching to middle of eye or slightly beyond.

Coloration. Body with yellowish, brownish or whitish background and coarse, dark- or pale-brown mottled pattern. Head pale brown or yellowish, check without pigmentation or with small, brown spots and vermiculation, ventral surface of head without pattern. Flank mottled, usually with irregularly set and shaped blotches or narrow, irregularly shaped bars on flank behind dorsal-fin origin. Back with 5–8 large, irregular shaped, brown blotches, wider than interspaces. No bold bar or blotch on caudal-fin base. Dorsal fin with many, small, black blotches on rays, forming 2–4 narrow, indistinct bands. Caudal fin with many small black blotches on rays, forming 3–4 indistinct bands. Pectoral, anal and pelvic fins hyaline in small individuals, with dark-brown or grey blotches on rays in larger individuals.

Distribution. Oxynoemacheilus muefiti has been found in the upper Murat River drainage as well as in the Eğri, a tributary to Atatürk reservoir.

Etymology. Oxynoemacheilus muefiti is named for Müfit Özuluğ (Istanbul) for his strong support to our work over many years. A noun in genitive, indeclinable.

Remarks. Our molecular data ( Fig. 1 ) place O. muefiti in the O. tigris species group. Based on DNA barcoding it is separated from all other species in the O. ercisianus group, and by a minimum K2P distance of 1.8% to O. ercisianus , which is the most closely related species based on the COI data we analysed. It is not supported by the PTP or mPTP delimitation as an own entity.

Oxynoemacheilus muefiti is known from two widely separated areas in the Euphrates drainage, the upper Murat River and the Eğri, a tributary to Atatürk reservoir ( Fig. 2 ). Both populations are distinguished by a minimum K2P distance of 1.0%. Our material is too limited to test, if there might be morphological differences between the two population groups which might be two species or two populations (see also Freyhof et al. 2019 for discussion). We suspect that the distribution area of O. muefiti might be still very incompletely known and many more populations will be discovered in the future which will fill the large gap in the known distribution range of the species.

Figures

FIGURE 1. Maximum likelihood estimation of the phylogenetic relationships based on the mitochondrial COI barcode region (K2P model, discrete Gamma distribution for rate differences with 3 categories (+G, parameter = 0.2094)). Nucleotide positions with less than 95% site coverage were eliminated, resulting in 605 analysed positions. Numbers of major nodes indicate bootstrap values from 1000 pseudoreplicates from the ML, NJ and MP method. X denotes highest possible support from all three methods (>95). Solid bars right to the specimen labels indicate species delimitation results from PTP followed by the results of the mPTP approach as dashed bars. Except to the out group. The tree is drawn to scale with branch lengths depicting number of substitutions per site.

FIGURE 2. Site scale records of species of the Oxynoemacheilus tigris species group based on material listed in this study.

FIGURE 15. Oxynoemacheilus muefiti, FFR 15532, holotype, 59 mm SL; Turkey: Murat River at Taşlıçay.

FIGURE 16. Oxynoemacheilus muefiti, from top: FFR 15532, paratype, 69 mm SL; Turkey: Murat River at Balıbostan; FFR 1432, paratypes, 57 mm SL; 43 mm SL; Turkey: Murat River at Taşlıçay.

FIGURE 17. Oxynoemacheilus muefiti, from top: FFR 15532, paratype, 69 mm SL; IUSHM 2019-1411, 52 mm SL; Turkey: Murat at Balıbostan; IUSHM 2019-1410, 68 mm SL, dorsal fin malformed, Turkey: stream near Sarıköy; FSJF 2556, 47 mm SL; Turkey: stream Eğri.