Oxynoemacheilus chaboras, Kaya & Kurtul & Aksu & Oral & Freyhof, 2024

Oxynoemacheilus chaboras sp. nov.

https://zoobank.org/A8C6E729-44C3-4B5C-9FCE-4A1906C9CDBE

Figs 2–4 View Figure 2 View Figure 3 View Figure 4

Type material. Holotype. FFR 15646 , 53 mm SL; Türkiye: Mardin prov.: stream Beyazsu 14 km north of Nusaybin , 37.1989, 41.3076 GoogleMaps .

Paratypes. FFR 1428 , 11, 46–60 mm SL: same data as holotype. GoogleMaps — FFR 15633 , 2, 40–51 mm SL; FSJF 4116, 4, 46–55; Türkiye: Mardin prov.: stream Beyazsu 12 km north of Nusaybin , 37.1730, 41.2690 GoogleMaps .

Genetic material. FFR DNA-Oxy378, 379, 380, 381; same data as holotype (GenBank accession numbers: OR689585 , OR689586 , OR689587 , OR689588 ) GoogleMaps .

Diagnosis. Oxynoemacheilus araxensis , O. argyrogramma , Oxynoemacheilus arsaniasus Freyhof, Kaya, Turan & Geiger, 2019 , Oxynoemacheilus bergianus (Derjavin, 1934), O. euphraticus , Oxynoemacheilus kaynaki Erk’akan, Özeren & Nalbant, 2008, Oxynoemacheilus muefiti Freyhof, Kaya, Turan & Geiger, 2019 , Oxynoemacheilus paucilepis (Erk’akan, Nalbant & Özeren, 2007), and Oxynoemacheilus tigris (Heckel, 1843) are other species of Oxynoemacheilus known from the Euphrates drainage ( Fig. 5 View Figure 5 ). Oxynoemacheilus chaboras , is distinguished from these by a combination of characters, none of them unique to the species.

Oxynoemacheilus chaboras belongs to a group of species ( O. argyrogramma , O. chaboras , O. euphraticus ) having two bold, black, round or comma-shaped blotches on the caudal-fin base (vs. absent in Oxynoemacheilus araxensis , O. arsaniasus , O. bergianus , O. kaynaki , O. muefiti , O. paucilepis , and O. tigris ). Furthermore, male O. chaboras have a suborbital groove (as in O. araxensis and O. bergianus vs. absent in O. arsaniasus , O. kaynaki , O. muefiti , O. paucilepis , and O. tigris ).

Oxynoemacheilus chaboras is further distinguished from O. araxensis by having a forked caudal fin (vs. slightly emarginate), and it is further distinguished from O. bergianus by having a forked caudal fin (shortest middle caudal-fin ray is 57–70% of longest ray of the upper caudal-fin lobe, vs. deeply emarginated, 70–84), and a deeper caudal peduncle (depth 1.4–1.7 times in its length vs. 1.7–3.5).

Oxynoemacheilus chaboras is distinguished from O. argyrogramma and O. euphraticus by possessing a mid-lateral series of blotches (vs. marbled or mottled pattern in O. argyrogramma ), without a mottling pattern above or below the blotches in front of dorsal-fin base (vs. irregularly mottled or marbled in O. euphraticus ), and having no, or a very short, incision in the upper lip (vs. a deep median incision in O. euphraticus ). It is further distinguished from O. euphraticus by having a deeper caudal peduncle (caudal-peduncle depth 1.4–1.7 times in its length vs. 2.0–2.8).

Description. See Figs 2–4 View Figure 2 View Figure 3 View Figure 4 for general appearance and Table 2 View Table 2 for morphometric data. Small-sized and slender species. Body deepest at dorsal fin origin or slightly anterior of it. Body width greatest at pectoral-fin base. Section of head roundish, flattened on ventral surface, straight or slightly convex in interorbital space, convex on snout. Snout blunt. Caudal peduncle compressed laterally, 1.4– 1.7 times longer than deep. Pelvic axillary lobe shallow and fully attached to flank. Pelvic-fin origin below second or third branched dorsal-fin ray. Anal-fin origin located in front of vertical of midline between dorsal and caudal-fin origins. Pectoral fin reaching to approximately 72–99% of distance from pectoral-fin origin to pelvic-fin origin. Pelvic fin reaching to genital papillae, rarely to anus; not reaching vertical of tip of last dorsal-fin ray. Anus about 40–70% of an eye diameter anterior to anal-fin origin. Anal fin not reaching caudal-fin base. No dorsal or ventral adipose crest on caudal peduncle. Largest known individual 60 mm SL.

Dorsal fin with 9½–10½ branched rays, outer margin straight or slightly concave. Anal fin with 5½ branched rays, outer margin straight. Pectoral fin with 9–11 branched rays, outer margin straight or slightly convex, tip pointed in male. Pelvic fin with 6 branched rays, outer margin straight or slightly convex. Caudal fin forked with (8+8)9+8 branched rays, lobes pointed. Flank and back covered by cycloid scales. Chest and belly without scales. Lateral line complete, terminating between origin of hypural complex and caudal fin base. Anterior nostril opening at end of a low, ovoid, flap-like tube. Posterior tip of anterior nostril overlapping posterior nostril when folded backwards. One central pore and one lateral pore on each side of supratemporal head canal, 3(4) + 9–10 pores in infraorbital canal, 8–9 pores in supraorbital canal, and 9–10 pores in mandibular canal. A suborbital groove in male. Mouth small, arched. Lips thick without furrows, lower lip thicker than upper lip. A median interruption in lower lip. Upper lip without median incision, rarely with a very small and short median incision. Processus dentiformis narrow and rounded. Lower jaw rounded, without median notch. Barbels long; inner rostral barbel reaching base of maxillary barbel, outer reaching to vertical of posterior of anterior eye margin. Maxillary barbel reaching or almost reaching to vertical of posterior eye-margin.

Coloration. Body with yellowish or cream background and dark-brown pattern in live and preserved individuals. Preserved individuals with a dark-grey, narrow inner-axial stripe, absent in life. Dorsal head and upper part of cheek brown, with marbled pattern. Ventral surface of head yellowish without pattern. Flank with 6–10 dark-brown bars or blotches, as much as, or thicker than, interspaces. Bars and blotches irregularly shaped and set, generally vertically elongated, sometimes oval, or horizontally elongated, usually extending to mid-dorsal saddles and meeting contra laterals. Back with 1–3 predorsal saddles, one saddle at dorsal-fin origin and one at posterior dorsal-fin base, and 3 saddles behind dorsal fin, as much as or thicker than interspaces. One dark-brown or black blotch at lower caudal-fin base, a second, much smaller blotch at uppermost caudal-fin base, both distinct in both live and preserved individuals. Dorsal, caudal and pectoral fins with many, small brown blotches on rays. These blotches forming 2–3 narrow bands on dorsal, and 3–5 on caudal. Pectoral, anal and pelvic fins hyaline, sometimes with a few dark-brown blotches on rays.

Distribution. The species known from the stream Beyazsu in the Euphrates drainage ( Figs 6 View Figure 6 , 7 View Figure 7 ).

Etymology. The species is named Chaboras, an ancient Greek name of the Khabur (Χαβώρας), as it was first documented by Ptolemy and Pliny the Elder ichthyofauna. A noun in genitive, indeclinable.