Oxynoemacheilus arsaniasus, 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 : 44-48

Oxynoemacheilus arsaniasus , new species

( Figs. 12–14 )

Holotype. FFR 15530, 57 mm SL; Turkey: Muş prov.: stream Kaynarca at Tepe , 39.107 41.492.

Paratypes. FFR 15531, 5, 36–54 mm SL; same data as holotype.— FFR 1449 , 1 , 49 mm SL; Turkey: Muş prov.: stream Kaynarca about 3 km southeast Tepe , 39.068, 41.529 .— FSJF 4019 , 12 , 46–97 mm SL; Turkey: Bitlis prov.: Reservoir of stream Karasu in Kaleli , 38.5537 42.0257 .

Material used in molecular genetic analysis. FFR 15509- DNA-057 ; Turkey: Muş prov.: stream Kaynarca at Tepe, 39.107 41.492. (GenBank accession numbers: MK 546483 ). — FSJF DNA- 2667 mm SL; Turkey: Bitlis prov.: stream Karasu in Kaleli , 38.5537 42.0257. (GenBank accession numbers: MK 546444 )

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Diagnosis. Oxynoemacheilus arsaniasus is distinguished from O. ercisianus by having a central pore in the supratemporal canal (vs. absent), a bold, dark-brown bar or vertically elongated blotch at the caudal fin-base, usually M-shaped or fused with a roundish or vertically elongate, dark-brown blotch at the vertical midline (vs. a mottled pigmentation not different from the flank pattern), usually wide, dark-brown, bold bands on the caudal fin (vs. narrow, pale-brown, indistinct), no or a shallow dorsal and ventral adipose crest in individuals larger than 50 mm SL (vs. a short and high crest), a longer and more slender caudal peduncle (caudal peduncle length 1.3–1.6 times its depth vs. 1.0–1.3), a larger eye (eye diameter 19–30% HL vs. 14–19), and a short prepelvic length (48–53% SL vs. 52–57).

The new species is distinguished from O. hazarensis by having no suborbital groove in the male (vs. present), no scales on the caudal peduncle (vs. present), a shorter outer rostral barbel (22–34% HL vs. 34–41), and a shorter maxillary barbel (24–30% HL vs. 32–40).

It is distinguished from O. kaynaki by having an incomplete lateral line (vs. complete), no scales on the flank (vs. present), no pelvic axillary lobe (vs. present), and no or a short dorsal adipose crest on the caudal peduncle (vs. a long adipose ridge).

Oxynoemacheilus arsaniasus is distinguished from O. tigris by having no scales on the flank (vs. present, usually isolated and deeply embedded), a bold, dark-brown bar or a vertically elongated blotch on the caudal-fin-base or a bar fused with a roundish or vertically elongate, dark-brown blotch at the vertical midline (vs. two bold, black spots in most individuals, no pigmentation in others), no or a short dorsal-adipose crest on the caudal peduncle not reaching to the vertical through the anal-fin base (vs. a long dorsal adipose crest reaching beyond the anal-fin origin, usually below the last dorsal-fin rays when folded down) and a more slender caudal-peduncle (caudal peduncle length 1.3–1.6 times its depth, vs. 0.9–1.2).

Oxynoemacheilus arsaniasus 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 having an incomplete lateral line (vs. complete), and no suborbital groove in the male (vs. present). It is distinguished from O. argyrogramma , O. bergianus , O. euphraticus , and O. samanticus by having an incomplete lateral line (vs. complete), a slightly emarginated caudal fin (vs. deeply emarginate or slightly forked), no suborbital groove in the male (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 arsaniasus is distinguished from O. paucilepis by having an incomplete lateral line (vs. complete), and no scales (vs. flank covered by isolated scales).

Description. See Figures 12–14 for general appearance and Table 2 for morphometric data. Medium-sized and moderately 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. No hump or 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 blunt or slightly pointed. Caudal peduncle compressed laterally, 1.3–1.6 times longer than deep. No axillary lobe present at base of pelvic fin. Pelvic-fin origin below first or second branched dorsal-fin ray. Anal-fin origin in front of vertical through middle between dorsal and caudal-fin origins. Pectoral fin reaching approximately 60–70% of distance from pectoral-fin origin to pelvic-fin origin. Pelvic fin not reaching vertical through tip of last dorsal-fin ray, not reaching anus. Anus about ½–1 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, to vertical through anal-fin base in some individuals. Crests usually absent in individuals smaller than 50 mm SL. A central pore in supratemporal canal. Margin of dorsal fin straight or convex. Caudal fin slightly emarginate. Largest known specimen 97 mm SL.

Dorsal fin with 8½ branched rays. Anal fin with 5½ branched rays. Caudal fin with 8+7 (n=7), 8+8 (3) branched rays. Pectoral fin with 10 (n=1) and 11 (n=5) and pelvic fin with 7 (n=5) and 8 (n=1) rays. No scales on flank and back. Lateral line incomplete, reaching to vertical through a point between about of one snout length in front of dorsal-fin origin and middle of caudal peduncle. 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 deep median interruption in lower lip. No or a shallow median incision in upper lip. Processus dentiformis narrow and rounded. No median notch in lower jaw. Barbels moderately long, 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 vertical through middle of eye or slightly behind posterior margin of pupil.

Coloration. Body with yellowish or pale-grey background and brown or dark-grey pattern. Head and cheek brown on top without, with few or many minute yellowish spots and vermiculation, ventral surface of head without pattern. Flank marbled, usually with 9–11 midlateral, irregularly shaped and spaced dark-brown blotches or bars. Back with a marbled pattern or with 6–7, dark-brown saddles irregularly shaped and set, slightly wider than interspaces, not fused to lateral bars or blotches. Upper caudal peduncle with a marbled pattern or with 2–3 dark-brown or grey saddles not fused with blotches or bars on flank. A bold, dark-brown bar or vertically elongated blotch at caudal fin-base, bar usually M-shaped or fused with a roundish or vertically elongate, dark-brown blotch at vertical midline. Dorsal-fin with dark-brown blotches on rays, forming 1–3 bands. Caudal-fins with many elongated, darkbrown blotches on rays, forming 1–5 wide or narrow, irregularly shaped, dark-brown bands. Pectoral, anal- and pelvic-fins hyaline in small individuals, with dark-brown or grey blotches on rays in larger individuals.

Distribution. Oxynoemacheilus arsaniasus has been found in the Murat River north of Muş as well as in the upper Karasu (Bitlis) River drainage. The Karasu (Bitlis) joins the Murat north-west of Muş. The Murat flows to the Keban reservoir in the upper Euphrates drainage.

Etymology. Oxynoemacheilus arsaniasus is named for the Arsanias, the antique name of the Murat River. An adjective based on the classical Latin adjective.

Remarks. Our molecular data ( Fig. 1 ) place O. arsaniasus in the O. tigris species group. Based on DNA barcoding it is well separated from all other species in the O. tigris group, and by a minimum K2P distance of 3.0% to O. kaynaki . It is also supported by the PTP approach (the two individuals are separated) and by the mPTP delimitation as a separate entity.

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 12. Oxynoemacheilus arsaniasus, FFR 15530, holotype, 57 mm SL; Turkey: stream Kaynarca.

FIGURE 13. Oxynoemacheilus arsaniasus, from top: FFR 15531, paratype, 54 mm SL; 38 mm SL; 39 mm SL; Turkey: stream Kaynarca.

FIGURE 14. Oxynoemacheilus arsaniasus, from top: FFR 15530, holotype, 57 mm SL; FFR 15531, paratype, 54 mm SL; Turkey: stream Kaynarca; FSJF 4019, 90 mm SL; Turkey: stream Karasu.