Oxynoemacheilus euphraticus ( Bănărescu & Nalbant, 1964 ), Banarescu & Nalbant, 1964

Freyhof, Jörg & Özuluğ, Müfit, 2017, Oxynoemacheilus hazarensis, a new species from Lake Hazar in Turkey, with remarks on O. euphraticus (Teleostei: Nemacheilidae), Zootaxa 4247 (4), pp. 378-390 : 385-387

Oxynoemacheilus euphraticus ( Bănărescu & Nalbant, 1964)

( Figs. 7–9 )

Noemacheilus insignis euphraticus Bănărescu & Nalbant, 1964:175 , Figs. 11–12

Oxynoemacheilus freyhofi Jouladeh –Roudbar, Eagderi & Hosseinpour, 2016: 93, Figs. 1–5

Material examined. ZMH 1889, holotype of Nemacheilus insignis euphraticus , 29 mm SL; ZMH 1890, 20 paratypes of N. i. euphraticus , 24–36 mm SL; Turkey: Malatya. — FSJF 1990, 24 , 25–61 mm SL; Turkey: Muş prov.: stream Page at Yaygın , about 30 km west of Muş, 38°55'N 41°16'E. — FSJF 1996, 5 , 36–55 mm SL; Turkey: Elazığ prov.: stream at village Karakocan , at street from Elazığ to Bingöl, 38°57'N 40°01'E. — FSJF 2636, 20 , 35– 60 mm SL; Turkey: Adıyaman prov.: upper River Göksu, 5 km northeast of Gölbaşı , 37° 50.217N 37° 41.088E. — FSJF 2910, 26 , 28–66 mm SL; Turkey: Sivas prov.: stream Kangal under railway bridge at Çetinkaya , 39.2516N 37.6189E. — FSJF 3376, 31 , 34.8–73.6 mm SL; Iraq: Rezan River near Ziraran, a tributary to Greater Zab River , 36°56.60'N 44°11.72'E.

Diagnosis. Oxynoemacheilus euphraticus is distinguished from the other Oxynoemacheilus species in the Euphrates and Tigris drainage by a combination of characters, none of them unique. Oxynoemacheilus euphraticus belongs to a group of species ( O. argyrogramma , O. bergianus , O. erdali , O. hanae , O. karunensis , O. longipinnis O. kurdistanicus O. parvinae and O. paucilepis ) having a suborbital groove in males (vs. absent in O. chomanicus , O. frenatus , O. gyndes , O. hazarensis , O. kaynaki , O. kiabii and O. zagrosensis ) and a deeply emarginate or forked caudal fin (vs. slightly emarginate or truncate in O. chomanicus , O. frenatus , O. gyndes , O. hazarensis , O. kaynaki , O. kiabii and O. zagrosensis ).

Oxynoemacheilus euphraticus is distinguished from O. bergianus , O. erdali , O. longipinnis and O. parvinae by having two prominent black jet-spots at the caudal-fin base (vs. absent), a deeper caudal peduncle (8–11% SL vs. 7–8) and the caudal peduncle usually with regularly shaped bars (vs. caudal peduncle mottled, with irregularly shaped dark-brown bars or large blotches). It should be noted, that in large individuals, especially in clear streams, the flank colour pattern might be very dark and might overlay the two spots at the caudal-fin base in O. euphraticus . In juvenile fishes, these two spots are always very well visible ( Fig. 7 ).

Oxynoemacheilus euphraticus is distinguished from O. hanae and O. karunensis by having a deep median incision in the upper lip (vs. no or a very short incision), a series of narrow and regularly or irregularly set and shaped bars at least on the flank behind the caudal-fin base (vs. a series of dark-brown roundish or ovoid blotches along the midlateral flank), the midlateral blotches reaching down to ventral side of caudal peduncle (vs. not reaching) and the bars on the flank behind the dorsal-fin-base usually being confluent with the saddles on the back (vs. midlateral blotches usually not confluent with saddles on back, but often overlapping).

Oxynoemacheilus euphraticus is also distinguished from O. karunensis by having a well developed pelvic axillary lobe with a free tip (vs. no or only a very rudimentary, shallow and knob-shaped, fully attached to the body), flank without spots, vermiculation or mottling, in some individuals with small, vertically-elongated and transversely-positioned blotches (vs. many minute dark-brown spots on the back, flank above lateral midline and caudal peduncle, with a mottled colour pattern in the interspaces of saddles and large blotches on the back or these interspaces with vermiculated pattern) and flank behind the dorsal-fin base with regularly or irregularly shaped bars usually confluent with the saddles on the back (vs. flank usually with a midlateral row of short, verticallyelongated blotches usually not confluent with the saddles on the back).

We were not able to find characters distinguishing O. kurdistanicus from O. euphraticus (see Discussion).

Distribution. Oxynoemacheilus euphraticus is very widespread in the Euphrates River drainage and records of O. hamwii from the Euphrates by Krupp & Schneider (1991) might belong to this species. Its presence in the Tigris drainage is confirmed by several findings in the Greater Zab and in streams flowing to the Greater Zab, one very small juvenile individual from the lower Lesser Zab, and from the Karun drainage in Iran. It might be more widespread.

Remarks. Freyhof et al. (2011) treat O. euphraticus as a synonym of O. argyrogramma as both species have two prominent black jet-spots on the caudal-fin base and a deeply emarginate caudal fin. Oxynoemacheilus argyrogramma has been described from the Queiq, an endorheic river west of the Euphrates. Oxynoemacheilus euphraticus has been described from the upper Euphrates drainage at Malatya in Turkey. Since the study by Freyhof et al. (2011), it turned out that there are two species in the upper Euphrates both distinguished by having two prominent black jet-spots on the caudal-fin base and a deeply emarginate caudal fin. Both species are well distinguished also by their COI sequences and by their colour pattern and the depth of the caudal peduncle, which is slender in one species and deep in the other (adults larger than 50 mm SL: caudal peduncle depth 2.0–2.8 times in the caudal peduncle length vs. 1.4–1.8). The species with the deep caudal peduncle is identified as O. argyrogramma . The syntypes of O. argyrogramma (NMW 48541, NMW 59913) from the Queiq have a deep caudal peduncle. Fishes from the Queiq drainage (Sünnep stream) collected by us (FSJF 2926), are superficially identical to the types and also have a deep caudal peduncle. COI sequences of fishes from the Queiq drainage and those from the adjacent Euphrates are almost identical. These are identified as O. argyrogramma .

The holotype and the paratypes of O. euphraticus are juveniles (24–36 mm SL) ( Fig. 7 ) and we compared them with juveniles of O. argyrogramma of about the same size (FSJF 2892: 26–38 mm SL) and with juveniles of the second species from the Euphrates (FSJF 2910: 28–35 mm SL). Already in the juveniles, the difference in the caudal peduncle depth is clear (caudal peduncle depth 1.5–1.8 times in the caudal peduncle length in O. argyrogramma , 2.1–2.8 in types of O. euphraticus , 2.0– 2.3 in fresh materials from the Euphrates). Therefore, we identify the second species, diagnosed by having two prominent black jet-spots on the caudal-fin base and a deeply emarginate caudal fin, as O. euphraticus and treat O. euphraticus as a valid species.

Juveniles of both species have a midlateral row of brown blotches on the flank. Adults of O. euphraticus ( Fig. 9 ) have bars on caudal peduncle (vs. a marbled colour pattern without bars on the flank in O. argyrogramma , Fig. 10 ). We found O. euphraticus in the area of Malatya and the species is widespread in the Euphrates and found also in the Tigris drainage. Oxynoemacheilus argyrogramma seems to be restricted to the Queiq and the westernmost tributaries of the Euphrates.

Jouladeh-Roudbar et al. (2016) described O. freyhofi from the Karun drainage in Iran without considering that O. euphraticus might be an available name for the species they found. Jouladeh-Roudbar et al. (2016) try to balance the lack of correctly identified comparison materials by applying molecular data from NCBI Genbank. That would make sense if all described species would be available from NCBI Genbank, and if the species from which these sequences are derived had been definitively identified, which is not the case. We found O. freyhofi to be distinguished from other populations of O. euphraticus only by 0.5% K2P sequence difference in the COI barcode region (own unpublished data). Jouladeh-Roudbar et al. (2016) diagnose O. freyhofi by having always 10½ branched dorsal-fin rays and lacking a suborbital groove in males. Indeed, O. euphraticus frequently, but not always has 10½ branched dorsal fin ray (8½–10½). We would be more than surprised if O. freyhofi lacks the suborbital groove in males. Jouladeh-Roudbar et al. (2016) examined only a single adult individual for their description of O. freyhofi , the holotype (60.3 mm SL), which might be a female. All 10 paratypes are juveniles (43– 45 mm SL). Juvenile individuals of Oxynoemacheilus species do not show the sexual dimorphism that is visible in adults. None of the characters provided in the description of O. freyhofi allows this species to be distinguished from O. euphraticus . However, in O. argyrogramma , not all males have a suborbital groove and it cannot be excluded, that some males of O. euphraticus might also lack a suborbital groove. Freyhof (2016) already treated O. freyhofi as a synonym of O. euphraticus without giving reasons and the case is therefore considered here again. It should be noted that it is the responsibility of the authors describing a new species to provide evidence that their species has not in fact yet been described.

When Kamangar et al. (2014) described O. kurdistanicus , they also followed Freyhof et al. (2011) and considered O. euphraticus as a synonym of O. argyrogramma . It is since turned out that this is not the case and that O. euphraticus represents a valid species (see above). The fishes identified as O. argyrogramma by Kamangar et al. (2014) were collected in the Iranian part of the Sirvan River, a tributary of the Tigris, and might in fact represent O. hanae . It was easy to distinguish O. kurdistanicus from O. hanae for Kamangar et al. (2014), but to distinguish O. kurdistanicus from O. euphraticus is a challenge. Jouladeh-Roudbar et al. (2016) give several morphometric differences between O. euphraticus (as O. freyhofi ) and O. kurdistanicus but all morphometric characters mentioned by Jouladeh-Roudbar et al. (2016) substantially overlap between both species (own data). Even the measurements given by Jouladeh-Roudbar et al. (2016) cannot be used, as no ranges were given for the morphometric characters distinguishing O. euphraticus from O. kurdistanicus . We are as a result unable to distinguish O. euphraticus from O. kurdistanicus and they might be just one species or two valid but cryptic species without (known) morphological differences.

Figures

FIGURE 1. Oxynoemacheilus hazarensis, IUSHM 2017 - 1171, holotype, 44 mm SL; Turkey: North-eastern shore of Lake Hazar.

FIGURE 2. Oxynoemacheilus hazarensis, FSJF 2512, paratypes, from top to bottom 57 mm SL, 49 mm SL, 44 mm SL, 38 mm SL; Turkey: North-eastern shore of Lake Hazar.

FIGURE 3. Oxynoemacheilus hazarensis, FSJF 2512, paratypes, from top to bottom 57 mm SL, 49 mm SL, 44 mm SL, 38 mm SL; Turkey: North-eastern shore of Lake Hazar.

FIGURE 4. Oxynoemacheilus hazarensis, FSJF 2512, paratype, 49 mm SL; Turkey: North-eastern shore of Lake Hazar. Orange spot at caudal-fin base present only in this individual.

FIGURE 5. Oxynoemacheilus hazarensis, not preserved, about 65 mm SL; Turkey: North-eastern shore of Lake Hazar.

FIGURE 7. Oxynoemacheilus euphraticus, ZMH 1890, paratypes, from top to bottom, 34 mm SL, 30 mm SL, 35 mm SL, 36 mm SL; Turkey: Malatya.

FIGURE 8. Oxynoemacheilus euphraticus, FSJF 2636, 58 mm SL; male showing suborbital groove; Turkey: River Göksu northeast of Gölbaşı.

FIGURE 9. Oxynoemacheilus euphraticus, from top to bottom, FSJF 2910, 55 mm SL; Turkey: stream Kangal under railway bridge at Çetinkaya; FSJF 2636, 60 mm SL; Turkey: upper River Göksu, 5 km northeast of Gölbaşı; FSJF 3376, 70 mm SL; Iraq: Rezan River near Ziraran.

FIGURE 10. Oxynoemacheilus argyrogramma, FSJF 2587, 45 mm SL; Turkey: stream Çakal, 13 km west of Adıyaman; FSJF 2926, 50 mm SL; Turkey: stream Sünnep, 10 km east of Kilis, Queiq drainage; FSJF 2935, 56 mm SL; Turkey: stream Merziman at Bağtepe, Euphrates drainage.