Oxynoemacheilus bergianus
Creators: name: Freyhof, Jörg
name: Kaya, Cüneyt
name: Geiger, Matthias F.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Cypriniformes
Nemacheilidae
Oxynoemacheilus
Oxynoemacheilus bergianus

description: Oxynoemacheilus bergianus (Derjavin, 1934)
(Fig. 4–11)
? Nemacheilus bergi Gratsianov, 1907: 163, 167 (based on Nemachilus spec.? of Berg, 1899: 30, 72 (type locality: Azerbaijan: Akstapha River [Akstafa, Agstafa; Aghstev, 41°15‘N 45°26‘E], right tributary of Kura River, Caspian basin)
Nemacheilus bergianus Derjavin, 1934:109, fig. 8. (type locality: Iran: Kisum village, Shah-rud, Sefid drainage).
Nemacheilus angorae lenkoranensis Abdurakhmanov, 1962: 285, fig. 50 (type locality: Azerbaijan: Lenkoran.
Orthrias brandti samantica Banarescu & Nalbant, in Banarescu, Nalbant & Balık, 1978: 263, fig. 4. (type locality: Turkey: tributary of Samanti, between Pinarbasi and Sarizi, Seyhan drainage)
Ilamnemacheilus longipinnis Coad & Nalbant, 2005: 304, fig. 1 (type locality: Iran: Meymeh River, a former tributary of Tigris-Euphrates River, 17 km west of Dehloran city and about 21 km east of Iraqi border, 32°45‘30“N 47°05‘30“E
Barbatula erdali Erk‘akan, Nalbant & Özeren, 2007: 78, fig. 8 (type locality: Turkey: Murat River — Agri, 39°40‘N 43°44‘E)
Oxynoemacheilus parvinae Sayyadzadeh, Eagderi & Esmaeili, 2016:238, figs. 2–10 (type locality: Iran: Leilehrud (Leileh River), a tributary of Sirvan River drainage at Sharvineh village, Javanrud city, Kermanshah Province, 34°49‘37.9“N, 46°21‘30.0“E.
Material examined. Kızılırmak drainage: FFR 1553, 2, 55–62 mm SL; Turkey: Yozgat prov.: stream Delice 2 km southeast of Yerköy, 39.6220N 34.4900E. — FFR 1556, 3, 37–55 mm SL; Turkey: Sinop prov.: stream Gökırmak at Çarşak 11 km east of Boyabat, 41.4530N 34.8890E. — FFR 1577, 19, 54–62 mm SL; Turkey: Samsun prov.: stream Soruk 20 km east of Vezirköprü, 41.1189N 35.2269E. — FSJF 2880, 22, 36–62 mm SL; Turkey: Sivas prov.: stream Yıldız between Yıldızeli and Sivas, 39.7585N 36.7643E. — FSJF 2904, 2, 43–45 mm SL; Turkey: Sivas prov.: Kızılırmak River south of Sivas at the road to Gürün, 39.7210N 36.9621E. — FSJF 2981, 1, 44 mm SL; Turkey: Sivas prov.: Kızılırmak River at Ortatopaç nouthwest of Şarkışla, 39.3813N 36.2504E. — FSJF 3137, 11, 37–66 mm SL; Turkey: Çorum prov.: stream Hamamözü between Dodurga and Laçin, 40.7987N 34.8567E. — FSJF 3150, 12, 49–68 mm SL; Turkey: Çankırı prov.: stream Devrez at Ilgaz, 40.9030N 33.6504E. — FSJF 3155, 37, 25–53 mm SL; Turkey: Çankırı prov.: stream Terme at Konak village 30km south of Çankırı, 40.3912N 33.6372E.
Material used in molecular genetic analysis. FSJF DNA-1406; Turkey: Sivas prov.: stream Yıldız between Yıldızeli and Sivas, 39.7585N 36.7643E (GenBank accession: OK316652).— FSJF DNA-1614; Turkey: Çankırı prov.: stream Devrez at Ilgaz, 40.9030N 33.6504E (GenBank accession: OK316630, OK316654).— FSJF DNA-2838; Turkey: Çankırı province, stream Şabanözü, 5 km south of Şabanözü, 40.4339N 33.2835E (GenBank accession: OK316758).
Seyhan drainage: FFR 15561, 9, 35–69 mm SL; Turkey: Kayseri prov.: stream Sarnaz a drainage of stream Zamantı at Taşçı, 38.1953N 35.7805E. — FSJF 2983, 15, 38–77 mm SL; Turkey: Kayseri prov.: stream Zamantı at Pınarbaşı, 38.7366N 36.4131E.
Material used in molecular genetic analysis.
FSJF DNA-1402 Turkey: Kayseri prov.: stream Zamantı at Pınarbaşı, 38.7366N 36.4131E (GenBank accession: KJ553908, KJ553807).
Upper Tigris drainage: — FSJF 2873, 1, 56 mm SL; Turkey: Elazığ prov.: Tigris River 5 km north of Maden, 38.4157N 39.6531E.— FSJF 2923, 2, 45–61 mm SL; Turkey: Batman prov.: stream Sason between Çatakköprü and Sason, 38.2622N 41.2591E.
Material used in molecular genetic analysis. FSJF DNA-1316; Turkey: Batman prov.: stream Sason between Çatakköprü and Sason, 38.2622N 41.2591E (GenBank accession: OK316595, OK316709, OK316751, OK316756).— FSJF DNA-1422; Turkey: Elazığ prov.: Tigris River 5 km north of Maden, 38.4157N 39.6531E (GenBank accession: OK316601).— FSJF DNA-2317; Iran: Sirvan drainage, (GenBank accession: OK316649, OK316627).
“ Oxynoemacheilus longipinnis ”: CMNFI 1979-0366, holotype, 36 mm SL; Iran: Meymeh River, 17 kilometers west of Dehloran, about 21 kilometers east of Iraqi border, 32.7583N 47.09167E.— CMNFI 1979-0367, 1, 41 mm SL; Iran: Khuzestan prov.: Meymeh River 11 km north of Dehloran, 32.7423N 47.1564E. — CMNFI 1979- 0365, 5, 32–40 mm SL; Iran: Khuzestan prov.: stream in Doveyrich drainage, 32.4167N 47.6083E. — FSJF 4056, 2, 53–56 mm SL; ZM-CBSU 1163, 1, 57 mm SL; ZM-CBSU 1166, 1, 43 mm SL; Iran: Ilam prov.: Meymeh River at Zarab, 33.140278N 46.928333E.
Material used in molecular genetic analysis. FSJF DNA-2723; Dowairij River about 5 km above reservoir, 32.6547N 47.5434E (GenBank accession: OK316680).— HRE-I577F; Iran: Tigris drainage, 33.1404N 46.9285E (GenBank accession: OK316741).— HRE-I578F; Iran: Tigris drainage, 33.1404N 46.9285E (GenBank accession: OK316637).— HRE-I580F; Iran: Tigris drainage, 33.1158N, 46.1158E (GenBank accession: OK316723).— HRE-I581F; Iran: Tigris drainage, 33.0461N, 46.5755E (GenBank accession: OK316633).
“ Oxynoemacheilus parvinae ”: FSJF 4053, 5, 51–70 mm SL; Iran: stream Leile, 34.8296N 46.3592E.— ZM-CBSU D222, 54.4 mm SL; D225, 58.2 mm SL; D226, 36.7 mm SL; D227, 59.0 mm SL; Iran: Kordestan prov.: Dehkan River at Abbas Abad, at road betwen Divandareh and Sanandaj, 35.5248N 47.0955E.
Material used in molecular genetic analysis. FSJF DNA-1687; Iran: Dehkan River flowing to Vahdat reservoir, 35.5220N 47.0945E (GenBank accession: OK316766, OK316740, OK316624).— FSJF DNA-1699; Iran: stream about two km south-east of Hoseynabad, Sanandaj, 35.5233N 47.0922E (GenBank accession: OK316644).— FSJF DNA-3289; Iran: stream south-east of Koile, 34.9033N 46.2082E (GenBank accession: OK067685).
Euphrates drainage: FFR 1457, 11, 64 –72 mm SL; Turkey: Malatya prov.: stream Sultansuyu 8 km east of Akçadağ, 38.3388N 38.0620E. — FFR 1467, 28, 54–64 mm SL; Turkey: Erzurum prov.: stream Baş 10 km east of Aşkale, 39.9478N 40.8040E. — FFR 15506, 25, 33–59 mm SL; Turkey: Ağrı prov.: Murat River 17 km west of Taşlıçay, 39.6785N 43.1887E. — FSJF 1993, 5, 44–55 mm SL; Turkey: Ağrı prov.: Murat east of Ağrı, 39.6640N 43.3175E. — FSJF 2547, 8, 42–67 mm SL; Turkey: Sivas prov.: stream Malcılı about 30 km north of Gürün, 5 km west of Mancılık, 39.0607N 37.1735E. — FSJF 2561, 14, 40–63 mm SL; Turkey: Adıyaman prov.: stream Eğri km south of Adıyaman, tributary to Atatürk Dam Lake, 37.7417N 38.3351E. — FSJF 3442, 13, 30–54 mm SL; Turkey: Ağrı prov.: Murat at Ballıbostan, 12 km east of Ağrı, 39.6789N 43.1896E. — FSJF 3674, 1, 59 mm SL; mm SL; Turkey: Bitlis prov.: stream Kaleli in Kareli, 38.5537N 42.0257E.
Material used in molecular genetic analysis. FSJF DNA-893; Turkey: Sivas prov.: stream Mancınık about 30 km north of Gürün, 5 km west of Mancılık, 39.0607N 37.1735E (GenBank accession: OK316787, OK316760, OK316789).— FSJF DNA-932; Turkey: Adıyaman prov.: stream Eğri km south of Adıyaman, tributary to Atatürk Dam Lake, 37.7422N 38.3351E (GenBank accession: MK546447, MK546448).— FSJF DNA-2398; Turkey: Ağrı prov.: Murat at Ballıbostan, 12 km east of Ağrı, 39.6789N 43.1896E (GenBank accession: OK316691).— FSJF DNA-2370; Turkey: Erzurum prov.: stream: Arkaçayırlar at Paşayurdu, on road from Ilıca to Aşkale, 39.9833N 40.9920E (GenBank accession: OK316693, OK316705).— FSJF DNA-2376; Turkey: Ağrı prov.: stream near Sarıköy, 16 km west of Eleşkirt, 39.8016N 42.4816E (GenBank accession: MK546449).
Caspian Sea basin: FSJF 3212, 6, 40–50 mm SL; Iran: Gilan prov.: Ghezel-ozan River, a tributary to Sefid.— FSJF 3216, 3, 38–58 mm SL; Iran: Guilan prov.: lower Sefid River below dam at Shar Bijar, 37.0205N 49.6311E.— FSJF 3249, 5, 31–61 mm SL; Iran: Ardabil prov.: Yalekhlou River north of Kalyan, 38.0025N 47.7684E.— FSJF 3261, 21, 38–64 mm SL; Iran: Guilan prov.: lower Sefid River below dam at Shar Bijar, 37.0205N 49.6311E.— FSJF 3459, 4, 74–82 mm SL; FSJF 3494, 7, 52–60 mm SL; Iran: Sefid River.
Material used in molecular genetic analysis. FSJF DNA-1688; Iran: West Azerbaijan prov.: stream Agh north of Aşağı Zengilan, 38.8616N 45.1344E (GenBank accession: MW591322).— FSJF DNA-1691; Iran: West Azerbaijan prov.: Qarah Su near Kultape, 39.2564N 47.5240E (GenBank accession: MK546446).— FSJF DNA-2012; Iran: Ardabil prov.: Yalekhlou River north of Kalyan, 38.0025N 47.7684E (GenBank accession: OK316672, OK316746).— FSJF DNA-2724; Iran: Zandshan prov.: upper Quezel Owzan River about 4 km west of Rajin Gowgelan, 37.1268N 47.7797E (GenBank accession: MK546451).— FSJF DNA-2725; Iran: Ardabil prov.: upper Quezel Owzan River at Nemehil, 37.2509N 48.4105E (GenBank accession: MW591332).— FSJF DNA-2727; Iran: Ardabil prov.: Baliqly River below reservoir, about 30 km upriver from Ardabil, 38.0739N 48.0827E (GenBank accession: MK546445). — HRE-N646F; Iran: Sefid drainage, 37.0201N 49.6333E (GenBank accession: OK316609). — HRE-N648F; Iran: Aras drainage, 38.5513N 47.8308E (GenBank accession: OK316780). — HRE-N649F; Iran: Aras drainage, 38.5513N 47.8308E (GenBank accession: OK316600). — ZFMK-ICH-TIS-52331; Azerbaijan: Lankaran drainage, 38.7105N 48.7729E (GenBank accession: OK316801). — ZFMK-ICH-TIS-52333; Azerbaijan: Lankaran drainage, 38.7105N 48.7729E (GenBank accession: OK316594). — ZFMK-ICH-TIS-52368; Azerbaijan: Lankaran drainage, 38.7105N 48.7729E (GenBank accession: OK316770). — ZFMK-ICH-TIS-52369; Azerbaijan: Lankaran drainage, 38.7105N 48.7729E (GenBank accession: OK316701).
Lake Namak basin: FSJF 1828, 28, 29–50 mm SL; FSJF 3230, 46, 32–46 mm SL; Iran: Albroz prov.: Kordan River near Karaj, 35.9531N 50.8375E.— FSJF 3227, 12, 38–52 mm SL; Iran: Iran Qom prov.: Quom River southwest of Shashme Ali, 34.3531N 50.5480E.— FSJF 3432, 7, 29–63 mm SL; Iran: stream Alakilise at Değirmenler, 40.0783N 42.1231E.
Material used in molecular genetic analysis. FSJF DNA-1993; Iran: Albroz prov.: Kordan River near Karaj, 35.9531N 50.8375E (GenBank accession: OK316757).— FSJF DNA-2317; Iran: Albroz prov.: Kordan River near Karaj, 35.9531N 50.8375E (GenBank accession: OK316728).— FSJF DNA-2736; Iran: Markazi prov.: stream north of Jalâyer, 34.8873N 50.0361E (GenBank accession: OK316690). — HRE-N647F; Iran: Sefid drainage, 37.0201N 49.6333E (GenBank accession: OK316726).— SMF 33103; Iran: Markazi prov.: Qara Chai in Tureh, 34.0353N 49.2828E (GenBank accession: OK316604).
Lake Urmia basin: HRE-M758; Iran: Urmia drainage, 37.9254N 47.3232E(GenBank accession: OK316634). — HRE-M759; Iran: Urmia basin, 37.9254N 47.3232E (GenBank accession: OK316681). — FSJF DNA-2012; Iran: Yalekhlou drainage, 38.0024N 47.7684E (GenBank accession: OK316672, OK316746).
Distribution. Oxynoemacheilus bergianus is known from the Kızılırmak drainage in the Anatolian Black Sea basin, the upper Seyhan drainage in the Mediterranean Sea basin, the upper Euphrates and Tigris drainages in Iran, Turkey and potentially in Iraq and Syria. It is also found in the Caspian Sea basin, where it is known from the Sefid in Iran northwest to the Aras River drainage. It also occurs in the Lake Namak and Urmia basins in Iran. See Fig. 2 for the distribution of this species.
Remarks. Oxynoemacheilus bergianus as recognised herein (including O. erdali, O. lenkoranensis, O. longipinnis, O. parvinae, O. samanticus) is distinguished from other species of the O. bergianus group by a minimum K2P distance of 2.9% to O. banarescui in the DNA barcode region and is supported as one entity only by mPTP.
Gratzianov (1907) described Nemacheilus bergi from the Akstapha [Akstafa] River based on Berg (1899). Recently, Çiçek et al. (2018) revalidated N. bergi as a species of Oxynoemacheilus, and the case was discussed in depth by Freyhof et al. (2021). We could not analyse DNA characters of O. bergi and have seen only a picture of a subadult individual (Freyhof et al., 2021). This information is too superficial to justify changing the name of such a widespread species as O. bergianus; the name might change again when more individuals and character states become available in the future. The identity of O. bergi remains unresolved and more fieldwork is needed to study the Oxynoemacheilus species of the Akstapha River to clarify this question. We cannot fully exclude the possibility that O. bergianus might be a junior synonym of O. bergi.
Barbatula erdali was described by Erk‘akan et al. (2007) from the upper Murat River drainage, a tributary of the Euphrates. It was already identified as a synonym of O. bergianus by Freyhof et al. (2019) and the fish on the drawing (Erk‘akan et al. (2007:78: Fig. 8) agrees very well with O. bergianus. Erk‘akan et al. (2007), however, did not distinguish O. erdali from O. bergianus. We found two molecular groups within the populations of O. bergianus in the Euphrates. The type locality of O. erdali is situated in the upper Murat at Ağrı. We examined fishes from the Murat at Ağrı (FSJF 1993, FSJF 3442/FSJF DNA-2398), which are indistinguishable from O. bergianus from the Sefid, the type locality of the species, by morphological and molecular characters. The clade found in the Euphrates that is different from the majority of O. bergianus, was found in the northernmost Euphrates drainage, north-east of Erzurum (FSJF DNA-2370, 39.9833N 40.9920E). This stream flows to the Karasu, another large tributary of the Euphrates beside the Murat. Although no voucher material is available from this population, we have a photograph of one individual (Fig. 4, right column, uppermost individual). While we cannot determine whether it might be morphologically different from O. bergianus, the fish in the figure is superficially indistinguishable from other populations of that species. The K2P distance of the fish from the Karasu and O. bergianus is only 1.2%, and both molecular clades are very likely conspecific.
Nemacheilus angorae lenkoranensis was described from Lenkoran (also spelled Lankaran) by Abdurakhmanov (1962). It is treated as a species of Oxynoemacheilus by Golzarianpour et al. (2011) and as a synonym of O. bergi by Çiçek et al. (2018) without examination of material or analysis of characters given in the description or shown in the figures. The Lenkoran River, having its estuary at Lenkoran, is a small tributary of the Caspian Sea between the Sefid and the Kura. The loach fauna of this and other coastal rivers in the area is poorly studied. We were able to include some samples from Iranian coastal rivers from south of the border between Azerbaijan and Iran in our molecular analysis and these are identified as O. bergianus. Boris Levin (Borok) allowed us to analyse some tissue samples he collected in the Lenkoran River in Azerbaijan and sent us some pictures of these fishes (Fig. 5). He also mentioned that there seems to be only a single species of nemacheilid loach in the Lenkoran River. While these individuals could be examined by us only from photos, the sequences derived from them cluster within O. bergianus. The vouchers of the tissue samples (Fig. 5) are slender loaches identical or very similar in body shape and colour pattern to O. bergianus. Abdurakhmanov (1962: fig. 50; reproduced here as Fig. 6) shows a slender loach with a narrow caudal peduncle and deeply emarginate caudal fin. It is distinguished from the loaches collected by B. Levin in the Lenkoran River by having a different snout shape and having the dorsal-fin origin above the pelvic-fin origin (vs. behind in fresh materials from Lenkoran). But these differences, as well as the unusual shape of the caudal fin could be due to limitations of the illustration. Indeed, there are rarely individuals of O. bergianus with the dorsal-fin origin above the pelvic-fin origin; and potentially, the type of O. lenkoranensis is such an individual. As there is no clear character to distinguish O. lenkoranensis from O. bergianus, we tentatively treat it as a synonym of the latter species awaiting a more detailed study of the loaches of the Lenkoran River.
Oxynoemacheilus samanticus (Fig. 7) was described from the upper Seyhan drainage and these fishes, as well as those from the Kızılırmak drainage, form their own cluster in our molecular analysis. Further, one population from the uppermost Euphrates, just beyond the watershed of the Kızılırmak and the Euphrates (FSJF 2547, stream Mancılık), is placed in this cluster. However, we found no confident morphological character states or combination of character states to distinguish these populations from O. bergianus. Oxynoemacheilus samanticus is distinguished from O. bergianus by a minimum K2P distance of 2.1% in the COI mtDNA barcode region and is supported as PTP and ASAP entity/entities. Due to the small molecular difference—with regard to the data generated from the reference dataset—between both groups of populations and the lack of morphological characters found in this study, O. samanticus is treated as a synonym of O. bergianus.
Coad & Nalbant (2005) describe O. longipinnis (Fig. 8) as a distinct genus, Ilamnemacheilus, based on a single, malformed individual. Freyhof et al. (2016) re-examined the holotype and additional material collected at almost the same locality and transferred I. longipinnis into the genus Oxynoemacheilus. Sayyadzadeh et al. (2017) distinguished O. longipinnis from O. bergianus by having an oval bony swim bladder capsule connected by a narrower manubrium (vs. angular shaped connected by a wider manubrium), no tubercles on the suborbital flap or pectoralfin rays in males (vs. present), and anal and pelvic fins hyaline (vs. with dark-brown spots, few in small individuals, on rays).
We are not aware of a study examining the variability of the structure of the bony swim bladder capsule connected to the age, the sex, the fixative, and dissecting skill of researcher and potentially also the habitat of a population of Oxynoemacheilus loaches. The four individuals studied of each of O. bergianus, O. longipinnis, and O. parvinae for this character (Fig. 11) did reveal a remarkable variability in the shape of the bony swim bladder capsule. There is a difference between O. bergianus and the other two species in our materials, as O. bergianus have a pointed projection of the upper wing of the bony ridge of the capsule (vs. absent in O. longipinnis and O. parvinae). This pointed projection is absent in the sole capsule of O. bergianus shown by Sayyadzadeh et al. (2017:237), indicating a higher, possibly inter-population variability in this character complex. Further, in one individual of O. parvinae (55 mm SL), there is also such a pointed projection on the left side (right side on Fig. 11), but absent on the right side and in the other individuals studied. This character state does not correspond to the difference mentioned by Sayyadzadeh et al. (2017) as the general shape of the capsule and the width of the manubrium are identical. Furthermore, Sayyadzadeh et al. (2017) distinguish O. longipinnis by the same character state from O. bergianus and O. parvinae, while we see no difference between O. longipinnis and O. parvinae. We are convinced that the shape and structure of the bony swim bladder capsule needs deeper study of more individuals and populations. We see no reason to treat O. longipinnis and O. parvinae as a valid species only because they lack the pointed projection seen in the only four individuals of O. bergianus from one population studied by us, as additionally given that the pointed projection is absent in the individual figured by Sayyadzadeh et al. (2017).
In O. bergianus, the suborbital flap is covered by tubercles during spring, a common situation in Oxynoemacheilus. These are nuptial tubercles and they are absent except during the spawning season. Further, nuptial tubercles are easily abraded during handling and it remains unclear whether O. longipinnis invariably lacks tubercles on the suborbital flap or the pectoral fin. We found a hyaline anal and pelvic fin in many examples of O. bergianus, disqualifying this character from consideration in the diagnosis of the species. Oxynoemacheilus longipinnis is distinguished from other species of the O. bergianus group by having a pale brown flank pattern (vs. dark brown). The colour pattern of O. longipinnis is found also in the other species, but the particular pale colour of the pattern is not. However, the intensity of coloration in freshwater fishes may depend on the substrate of the stream inhabited, the turbidity of the water and other ecological factors. We do not consider the intensity of coloration by itself as a character suitable to distinguish closely related populations as species. Oxynoemacheilus longipinnis is distinguished by a minimum K2P distance of 2.1% to O. bergianus (Sayyadzadeh et al. 2017).
Sayyadzadeh et al. (2016) distinguish O. parvinae (Fig. 9) from O. bergianus by having 8½–9½ branched dorsal-fin rays (vs. 7½–8½), and large to medium dark-brown spots especially on the postdorsal part in some individuals, independent of size and sex (vs. small and more regular bars). As most individuals of both species have 8½ branched dorsal-fin rays, this character cannot be used to distinguish between the species. Although Sayyadzadeh et al. (2016) correctly point out differences in colour pattern, the colour pattern in O. bergianus is very variable and individuals indistinguishable from O. parvinae are commonly found, especially in the Euphrates and in the Aras, occurring also in the Black Sea basin. Sayyadzadeh et al. (2016) further distinguish O. parvinae as having an angular bony swim-bladder capsule (oval in O. longipinnis). Sayyadzadeh et al. (2016) did not mention how many individuals were examined for this difficult-to-prepare and destructive character, and whether there is variability in some character states. See remarks above on this character. Oxynoemacheilus longipinnis and O. parvinae are distinguished from O. bergianus by minimum K2P distances of 1.4% and 1.8% (Sayyadzadeh et al. 2016). Due to the small molecular difference between these groups of populations and the lack of morphological characters found in this study, O. longipinnis and O. parvinae are treated as synonyms of O. bergianus.
Furthermore, there is an additional group of populations (Fig. 10) found in the upper Tigris and in the Sirvan, which is a tributary of the Tigris in Iran and Iraq. These fishes are distinguished by a minimum K2P distance of 1.5% from O. longipinnis, 1.4% from O. parvinae and 2.0% from O. bergianus in the COI mtDNA barcode region. It is also supported as PTP and ASAP entity. We identify these populations as O. bergianus and do not recognise O. bergianus and the fishes from the molecular clade from the upper Tigris as “cryptic species” due to their close relationship and absence of diagnostic morphological characters.
The depth of the caudal peduncle, which is often a stable character used to distinguish species in Oxynoemacheilus, is very variable in O. bergianus. Although most populations of O. bergianus have a rather slender or very slender caudal peduncle (caudal-peduncle depth 2.5–2.9 times in its length), we found also one population in the Euphrates (FSJF 2561) with a deeper caudal peduncle (1.9–2.0, n=2). In O. banarescui, this character is equally variable and in FSJF 3169 it is 1.6–2.3 (n=8), in FSJF 3122 it is 2.6–2.8 (n=5), and in FSJF 3119 it is 1.6–2.8 (n=7). We sequenced individuals from FSJF 3169 (FSJF DNA-1626) and FSJF 3119 (FSJF DNA-1631) and found them to be situated in the same molecular clade. Clearly, this character does not allow the two species to be distinguished and we found no other character to separate O. banarescui from O. bergianus.
On the back behind the dorsal-fin base, O. bergianus from the Sefid and Namak basin usually have relatively small saddles and a mottled or finely marbled flank pattern with narrow, vertically elongate blotches. These blotches are usually not connected to the saddles and are often continuous through the midlateral line. Although such a colour pattern is less common in the Euphrates and the Aras, where most individuals have large, bold saddles often reaching down to the lateral midline and come in contact with distinct, vertically elongate but narrow blotches below the lateral midline. Here, the shape and position of lateral blotches is notably incongruent with those of the saddles: they usually do not form continuous bars but are interrupted in shape and position at the lateral midline. This colour pattern is also found in fishes in the Sefid and Namak basin but is less common there. A variety of intermediate patterns was found in all populations where larger series of individuals were available.
description: Published as part of Freyhof, Jörg, Kaya, Cüneyt & Geiger, Matthias F., 2022, A practical approach to revise the Oxynoemacheilus bergianus species group (Teleostei: Nemacheilidae), pp. 151-194 in Zootaxa 5128 (2) on pages 169-175, DOI: 10.11646/zootaxa.5128.2.1, http://zenodo.org/record/6479752