Zoosyst. Evol. 100 (2) 2024, 457-468 | DOI 10.3897/zse.100.118612 Ate BERLIN Oxynoemacheilus chaboras, a new loach species from the Euphrates drainage in Ttirkiye (Teleoste1, Nemacheilidae) Ciineyt Kaya!, Irmak Kurtul*?, Ismail Aksu, Miinevver Oral!, Jorg Freyhof* Recep Tayyip Erdogan University, Faculty of Fisheries, 53100 Rize, Turkiye Marine and Inland Waters Sciences and Technology Department, Faculty of Fisheries, Ege University, Izmir, Turkiye Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Poole, Dorset, UK FW NM Museum fiir Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, 10115 Berlin, Germany https://zoobank. org/3 1342190-DE9E-42A 9-AF83-ADSAE4F0C7D1 Corresponding author: Ciineyt Kaya (cnytkaya@yahoo.com) Academic editor: Nicolas Hubert # Received 13 January 2024 # Accepted 28 March 2024 Published 26 April 2024 Abstract Oxynoemacheilus chaboras, new species, from the stream Beyazsu in the Euphrates drainage, belongs to the O. persa species group, being closely related to O. shehabi from the Orontes, O. sarus from the Seyhan and Ceyhan, O. euphraticus from the Euphrates and Tigris, O. karunensis from the Karkheh, and O. persa from Central Iran. The new species is distinguished from others in the O. persa group by having 8-9 pores in the supraorbital canal, two distinct black blotches at the caudal-fin base, a rudimentary and shallow pelvic axillary lobe, 6—10 irregularly shaped bars on the flank, and a deep head, body, and caudal peduncle. Oxynoemachei- lus chaboras sp. nov. is most closely related to O. euphraticus, from which it is differentiated by a mean uncorrected p-distance of 3.24% (min. 3.09%) in its COI barcode gene. Key Words Cypriniformes, Cytochrome c oxidase subunit I, freshwater fish, taxonomy, Western Asia Introduction The genus Oxynoemacheilus Banarescu & Nalbant, 1966, with 63 recognised species, is the most speciose genus of freshwater fishes in the western Palaearctic (Yogurtcuog- lu et al. 2022). The hotspot of species richness of Oxy- noemacheilus is Mesopotamia and the adjacent Levant, where there are 21 species of the genus only in the Ti- egris-Euphrates drainage. This high species richness can be attributed to several factors such as the unique hydro- logical conditions, diverse habitat types, and historical biogeographical processes of the region. Seven species are endemic to the Euphrates drainage, and 11 are endem- ic to the Tigris drainage (Freyhof et al. 2021, 2022). But additional species of Oxynoemacheilus are still being dis- covered in this region, as vast areas especially in Iraq and Syria remain unexplored. There are many tributaries to the upper and middle Euphrates. One of these rivers is the Khabur that has few springs in Turkiye, but mostly flows in Syria. The stream Beyazsu, located in the Turkish Mardin province, is one of the headwater streams in the Khabour drainage. It flows into Syria after crossing the border at the city of Nusaybin, only 17.5 km below its source, the spring Beyazsu (Canpo- lat and BozdoSan 2019). This karstic spring has much wa- ter throughout the year and its average annual flow rate is approximately 3.8 m?/sec. (Canpolat and Bozdogan 2019). Until now, only Turan et al. (2014) seems to have stud- ied the fishes of the Beyazsu and reported the presence of Alburnus caeruleus Heckel, 1843, Alburnus sellal Heck- el, 1843 (as Alburnus mossulensis Heckel, 1843), Bar- bus lacerta Heckel, 1843, Capoeta damascina (Valenci- ennes, 1842) (as Capoeta umbla (Heckel, 1843)), Garra rufa (Heckel, 1843), and an unidentified species of genus Copyright Kaya, C. et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 458 Kaya, C. et al.: Oxynoemacheilus chaboras, a new loach species from the Euphrates drainage Oxynoemacheilus. These authors described A/burnoides emineae Turan, Kaya, Ekmekci & Dogan, 2014 as a new species from the stream Beyazsu, indicating its unique fauna. Here we examine the Oxynoemacheilus population from the Beyazsu in detail to test 1f they might represent an undescribed species. Materials and methods The care of experimental animals was consistent with the Republic of Turkiye’s animal welfare laws, guidelines, and policies. After anaesthesia, fishes were fixed in 5% formalin and stored in 70% ethanol, fin clips directly fixed in 99% ethanol. Measurements were made with a dial calliper, recorded to 0.1 mm, from a precise point-to- point approach, never by projections. Methods for counts and measurements followed Kottelat and Freyhof (2007), structures of the suborbital groove and the adipose crest followed Freyhof et al. (2019), and nomenclature of head pores followed Kottelat (1990). Standard length is mea- sured from the tip of the snout to the posterior extremity of the hypural complex. The length of the caudal peduncle is measured from behind the base of the last anal-fin ray to the posterior extremity of the hypural complex, at mid- height of the caudal-fin base. The last two branched rays articulating on a single pterygiophore in the dorsal and anal fins are counted as “1'4”. Simple rays of dorsal- and anal-fins are not counted as they are deeply embedded. Morphological data for Oxynoemacheilus zagrosensis Kamangar, Prokofiev, Ghaderi & Nalbant, 2014 are taken from Kamangar et al. (2014) and its position in the Oxy- noemacheilus persa (Heckel, 1847) group follow Freyhof and Geiger (2021). Abbreviations used SL, standard length; HL, head length; Collection codes: FFR, Recep Tayyip Erdogan University Zoology Collec- tion of the Faculty of Fisheries, Rize; FSJF, Fischsam- mlung J. Freyhof, Berlin, Germany. IUSHM, Istanbul University, Faculty of Science, Hydrobiology Muse- um, Istanbul; NMW, Natural History Museum Vienna; ZFMK-ICH, Zoological Research Museum Alexander Koenig, Ichthyology Collection, Bonn; ZMH, Zoolo- gisches Museum Hamburg, Hamburg. DNA extraction, PCR and sequencing Genomic DNA extraction of Oxynoemacheilus specimens was performed according to the application protocol rec- ommended by the manufacturer using the DNeasy Blood & Tissue Kit (Qiagen, Hilden, Germany). Amplification of the barcode region of the cytochrome c oxidase subunit 1 (COI) gene of vertebrate mitochondrial DNA was per- formed according to Bektas et al. (2022)’s thermocycler zse.pensoft.net conditions of which PCR protocol (4 min. first denatur- ation at 94 °C, followed by 30 cycles of denaturing for 30 1 min. at 94 °C, annealing for 30 sec. at 61 °C, extending for | min. at 72 °C and final extension for 7 min. at 72 °C) using forward FishF1 (5’-TCAACCAACCACAAAGA- CATTGGCAC-3’; Ward et al. 2005) and reverse FishR1 (5’-TAGACTTCTGGGTGGCCAAAGAATCA-3’; Ward et al. 2005) primers were used for amplification. PCR products were purified using the QIAquick PCR Purification Kit (Qiagen, Hilden, Germany) and bidirec- tional sequencing of PCR products was performed with an ABI PRISM 3730x1 Genetic Analyser using a Big- Dye Terminator 3.1 cycle sequencing ready reaction kit (Applied Biosystem) at Macrogen Europe. The obtained sequences were deposited in NCBI’s GenBank with the accession numbes between OR689585—OR689588. Molecular analysis Oxynoemacheilus species distributed in the Euphrates and all other species, except O. zagrosensis, of the O. persa species group, as well as all other species known from the Euphrates drainage, were included in our dataset (Fig. 1). References to the sequences downloaded from Genbank are as follows: Geiger et al. (2014); Esmaeili et al. (2014); Freyhof et al. (2016); Sayyadzadeh and Esmaeili (2020); Kaya et al. (2020); Freyhof and Geiger (2021); Bektas et al. (2022); Freyhof et al. (2022). The chromatograms of raw COI sequences obtained after sequencing were ex- amined with the Bioedit 7.2.5 (Hall, 1999) program and the detected errors were manually edited. Base composi- tion, and distinctive and diagnostic nucleotide positions were determined with the MEGA version X (Kumar et al. 2018) programme. The mean inter-species genetic distance values of Oxynoemacheilus were calculated in MEGA X according to the uncorrected p-distance model (Srivathsan and Meier 2012). Phylogenetic relationships among Oxynoemachei- Jus species were estimated using Maximum Likeli- hood (ML; Felsenstein 1981) algorithm in MEGA X programme, and Bayesian analysis (BI) in MrBayes v3.2.1 programme (Ronquist et al. 2012). For ML and BI analyses, the best-fit evolution models were deter- mined according to Akaike Information Criteria (AIC) and Bayesian Information Criteria (BIC) in the jMod- eltest 0.1.1 (Posada 2008). The ML tree was generated with 1000 bootstrap replicates using the GTR+G model that was selected by the lowest AIC score. The BI tree was generated implementing the GIR+G model that was selected by the lowest BIC score. The BI analyses were run for 5 million generations, sampling every 1000 generations. A conservative 25% of the trees were dis- carded as burn-in based on Bayesian analysis. No fur- ther software was used for checking the runs’ conver- gence. Visualization of the BI tree was performed by iTOL (Interactive Tree of Life; https://itol.embl.de/), a web-based software. Zoosyst. Evol. 100 (2) 2024, 457-468 459 69/0.99 » Oxynoemacheilus euphraticus Iraq Rubar-Shakiu (MW378597) Oxynoemacheilus euphraticus Iraq Greater Zab Tigris (OK316708) Oxynoemacheilus euphraticus Turkiye Tohma Euphrates (MMK546456) Oxynoemacheilus euphraticus Turkiye Goksu Euphrates (MMW378588) Oxynoemacheilus euphraticus Turkiye Tohma Euphrates (OL855785) 91/0.99 | Oxynoemacheilus euphraticus Iraq Lesser Zab Tigris (MW378584) Oxynoemacheilus euphraticus Turkiye Murat Euphrates (OL855783) Oxynoemacheilus euphraticus Turkiye alti Suyu Euphrates (0OK316754) Oxynoemacheilus euphraticus Turkiye Murat Euphrates (OL855786) 60/0.87 Oxynoemacheilus euphraticus Turkiye Tohma Euphrates (OL855784) Oxynoemachelilus euphraticus Iran Sirvan Tigris (MW378596) 100/11] Oxynoemacheilus shehabi Syria Orontes (KJ554073) Oxynoemacheilus shehabi Syria Orontes (KJ553795) 75/9.99 || OXynoemacheilus chaboras Turkiye Beyazsu Euphrates (OR689586) Oxynoemacheilus chaboras Turkiye Beyazsu Euphrates (OR689585) Oxynoemacheilus chaboras Turkiye Beyazsu Euphrates (OR689588) ols Oxynoemacheilus chaboras Turkiye Beyazsu Euphrates (OR689587, 7710.96 100/1; Oxynoemacheilus sarus Turkiye Seyhan (OL855826) 100/1 1s4 Oxynoemacheilus sarus Turkiye Ceyhan (OL855825) Oxynoemacheilus persa Iran Kor (KP050531) d0/0.95 Oxynoemacheilus karunensis Iran Karkheh (MW136439) 100/1L_ Oxynoemacheilus karunensis Iran Karkheh (OKO67686) 1090/1] Oxynoemacheilus kentritensis Turkiye Botan Tigris (OL855813) Oxynoemacheilus kentritensis Turkiye Botan Tigris (MMW378593) Oxynoemacheilus zarzianus Iran Lesser Zab Tigris (MW378594) me p7/1f Oxynoemacheilus marunensis Iran Marun (MW136427) Oxynoemacheilus marunensis Iran Marun (MW136428) 640.947 Oxynoemacheilus argyrogramma Turkiye Qweik (OL855752) 88/0.97 “A _ 10/1 Oxynoemacheilus argyrogramma Turkiye Merziman Euphrates (KU928280) a Oxynoemacheilus argyrogramma Turkiye Karasu Euphrates (OL855750) Oxynoemacheilus hanae Iraq Sirvan Tigris (MMW378595) 064 il Oxynoemacheilus hanae Iraq Sirvan Tigris (MW378592) oor Oxynoemacheilus chomanicus Iraq Lesser Zab Tigris (MW378582) Oxynoemacheilus chomanicus Iraq Lesser Zab Tigris (MW378585) ae Oxynoemacheilus zagrosensis Iran Choman Tigris (MW136432) ales Oxynoemacheilus zagrosensis Iran Choman Tigris (MW136433) Oxynoemacheilus kurdistanicus Iraq Lesser Zab Tigris (MW378581) 100/1L Oxynoemacheilus kurdistanicus Iraq Lesser Zab Tigris (MW378586) Oxynoemacheilus tigris Turkiye Merziman Euphrates (MK546479) Oxynoemacheilus arsaniasus Turkiye Murat Euphrates (OL855755) Oxynoemacheilus kaynaki Turkiye Tohma Euphrates (OL855805) Oxynoemacheilus kaynaki Turkiye Goksu Euphrates (OL855808) main Oxynoemacheilus muefiti Turkiye Murat Euphrates (OL855816) 100/11 Oyynoemacheilus muefiti Turkiye Murat Euphrates (MK546467) 100/1 Oxynoemacheilus araxensis Turkiye Karasu Euphrates (OL855748) 83/0.94] 98/1 Oxynoemacheilus paucilepis Turkiye Tohma Euphrates (OL855820) 61/0.83 Oxynoemacheilus bergianus Turkiye Goksu Euphrates (OL855765) sist Oxynoemacheilus bergianus Turkiye Euphrates (0L855766) Seminemacheilus attalicus (KJ554719) Turcinoemacheilus cf. kosswigi (KJ179258) Paracobitis salihae (MT651606) -———— ML/BI 0.050 Figure 1. Maximum Likelihood (ML) phylogenetic tree was reconstructed based on the COI-Barcode gene. ML and BI methods resulted in generally similar topologies with minor differences, and therefore only the ML tree is shown. The bootstrap values of ML and posterior probability values of BI are indicated on nodes (ML/BI). The bootstrap percentage values (BP) > 50% from ML analysis and Bayesian posterior probabilities (PP) > 0.50 are shown on the nodes. zse.pensoft.net 460 Results Sequence characteristic and phylogenetic reconstruction Molecular analysis was conducted with four newly-gen- erated DNA barcodes (see Genetic material section) and in addition already published data from NCBI GenBank. The average nucleotide frequency of four sequences of O. chaboras were A = 22.0%, T = 30.2%, C = 28.2% and G = 19.7%, and the nucleotide composition was A-T (52.2%) rich. Although the phylogenetic tree topologies reconstructed by both ML and BI methods indicated some minor differences from each other, they were gen- erally compatible. In both topologies, some of the internal branches corresponding to the phylogenetic relationships between species, were weakly supported (Fig. 1). The members of the O. persa species group (as defined by Freyhof and Geiger 2021) are distributed in two sub- clades with strong support according to the BI (PP: 0.96; Fig. 1) and ML (BP: 77%; Fig. 1) results. The first sub- clade includes O. chaboras, Oxynoemacheilus shehabi Freyhof & Geiger, 2021, Oxynoemacheilus euphraticus (Banarescu & Nalbant, 1964), O. persa, Oxynoemachei- lus sarus Freyhof, YoSurtcuoSlu & Kaya, 2021 and Oxy- noemacheilus karunensis Freyhof, 2016, while the sec- ond sub-clade includes Oxynoemacheilus argyrogramma (Heckel, 1847), Oxynoemacheilus kentritensis Freyhof, Kaya & Turan, 2017, Oxynoemacheilus zarzianus Frey- hof & Geiger, 2017, Oxynoemacheilus hanae Freyhof & Abdullah, 2017, Oxynoemacheilus kurdistanicus Kaman- gar, Prokofiev, Ghaderi & Nalbant, 2014, Oxynoemachei- lus marunensis Sayyadzadeh & Esmaeili, 2020, O. zagro- sensis and O. chomanicus. Oxynoemacheilus chaboras clusters as the sister species of the first sub-clade with weak support (BP: less than 50%; PP: 0.54; Fig. 1). Oxy- noemacheilus chaboras 1s distinguished from O. euphra- ticus, O. shehabi, O. persa, O. sarus and O. karunensis by 19, 23, 23, 27 and 29 diagnostic base positions, re- spectively. It is genetically most similar to O. euphrati- cus with a mean uncorrected p-distance value of 3.24% (minimum 3.09% — maximum 3.58%). It is distinguished from O. shehabi, O. persa, O. sarus and O. karunensis by mean 3.82% (min. 3.74%), 3.82% (min. 3.74%), 4.88% (min. 4.39%) and 5.20% (min. 4.88%), respectively. Ta- ble 1 displays the mean pairwise genetic distance results for each species. Oxynoemacheilus chaboras sp. nov. https://zoobank.org/A8C6E729-44C3-4B5C-9FCE-4A 1906C9CDBE Figs 2-4 Type material. Holotype. FFR 15646, 53 mm SL; Turki- ye: Mardin prov.: stream Beyazsu 14 km north of Nusay- bin, 37.1989, 41.3076. Paratypes. FFR 1428, 11, 46-60 mm SL: same data as holotype. — FFR 15633, 2, 40-51 mm SL; FSJF 4116, zse.pensoft.net Kaya, C. et al.: Oxynoemacheilus chaboras, a new loach species from the Euphrates drainage 4, 46-55; Turkiye: Mardin prov.: stream Beyazsu 12 km north of Nusaybin, 37.1730, 41.2690. Genetic material. FFR DNA-Oxy378, 379, 380, 381; same data as holotype (GenBank accession numbers: OR689585, OR689586, OR689587, OR689588). Diagnosis. Oxynoemacheilus araxensis, O. argyro- gramma, Oxynoemacheilus arsaniasus Freyhof, Kaya, Turan & Geiger, 2019, Oxynoemacheilus bergianus (Der- javin, 1934), O. euphraticus, Oxynoemacheilus kaynaki Erk’akan, Ozeren & Nalbant, 2008, Oxynoemacheilus muefiti Freyhof, Kaya, Turan & Geiger, 2019, Oxynoe- macheilus paucilepis (Erk’akan, Nalbant & Ozeren, 2007), and Oxynoemacheilus tigris (Heckel, 1843) are other species of Oxynoemacheilus known from the Eu- phrates drainage (Fig. 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 spe- cies (O. argyrogramma, O. chaboras, O. euphraticus) having two bold, black, round or comma-shaped blotch- es on the caudal-fin base (vs. absent in Oxynoemachei- lus 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 mid- dle 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 fur- ther distinguished from O. euphraticus by having a deep- er caudal peduncle (caudal-peduncle depth 1.4—1.7 times in its length vs. 2.0—2.8). Description. See Figs 2-4 for general appearance and Table 2 for morphometric data. Small-sized and slender species. Body deepest at dorsal fin origin or slightly an- terior of it. Body width greatest at pectoral-fin base. Sec- tion 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 Zoosyst. Evol. 100 (2) 2024, 457-468 461 Table 1. The interspecies genetic distances calculated by the uncorrected p-distance model for the Oxynoemacheilus species of Euphrates-Tigris and other O. persa species group. Species 1 2 3 4 5 6 7 8 9 10 1 O. chaboras 2 O. euphraticus 0.0324 3 O. shehabi 0.0382 0.0300 4 O. persa 0.0382 0.0265 0.0423 5 O. marunensis 0.0455 0.0340 0.0431 0.0431 6 O. hanae 0.0455 0.0349 0.0374 0.0439 0.0285 7 O. kurdistanicus 0.0463 0.0366 0.0455 0.0512 0.0268 0.0301 8 O. kentritensis 0.0472 0.0356 0.0415 0.0480 0.0390 0.0366 0.0415 9 O. zagrosensis 0.0488 0.0323 0.0480 0.0480 0.0260 0.0268 0.0220 0.0374 10 O.sarus 0.0488 0.0358 0.0415 0.0431 0.0520 0.0480 0.0545 0.0504 0.0537 11 O. argyrogramma 0.0507 0.0406 0.0509 0.0472 0.0388 0.0390 0.0388 0.0480 0.0363 0.0604 12. O. zarzianus 0.0512 0.0395 0.0488 0.0423 0.0325 0.0341 0.0390 0.0415 0.0350 0.0545 13 O.chomanicus 0.0512 0.0332 0.0455 0.0488 0.0268 0.0309 0.0260 0.0415 0.0187 0.0545 14. O. karunensis 0.0520 0.0414 0.0488 0.0374 0.0593 0.0537 0.0577 0.0577 0.0569 0.0472 15. O. araxensis 0.0772 0.0706 0.0764 0.0732 0.0854 0.0829 0.0837 0.0724 0.0854 0.0732 16 O. kaynaki 0.0789 0.0683 0.0715 0.0764 0.0772 0.0780 0.0780 0.0756 0.0732 0.0894 17 O. arsaniasus 0.0821 0.0716 0.0715 0.0780 0.0756 0.0764 0.0748 0.0740 0.0691 0.0854 18 O. tigris 0.0821 0.0688 0.0699 0.0748 0.0789 0.0780 0.0846 0.0724 0.0780 0.0813 19 O. muefiti 0.0894 0.0796 0.0821 0.0846 0.0862 0.0854 0.0878 0.0813 0.0756 0.0967 20 O. paucilepis 0.1024 0.0948 0.0878 0.0976 0.0951 0.0959 0.0935 0.0870 0.0927 0.0967 21 O. bergianus 0.1122 0.1156 0.1220 0.1122 0.1228 0.1171 0.1146 0.1098 0.1146 0.1179 11 12 13 14 15 16 17 18 19 20 1 O. chaboras 2 O. euphraticus 3 O. shehabi 4 O. persa 5 O. marunensis ) O. hanae vi O. kurdistanicus 8 O. kentritensis 9 0. zagrosensis 10 O. sarus 11 O. argyrogramma 12 O. zarzianus 0.0455 13. O.chomanicus 0.0390 0.0358 14 O. karunensis 0.0515 0.0650 0.0537 15. O. araxensis 0.0808 0.0748 0.0862 0.0862 16 O. kaynaki 0.0705 0.0748 0.0683 0.0902 0.0878 17. O. arsaniasus 0.0721 0.0732 0.0683 0.0902 0.0846 0.0228 18 O. tigris 0.0770 0.0732 0.0715 0.0894 0.0862 0.0423 0.0488 19 O. muefiti 0.0851 0.0813 0.0829 0.1024 0.0967 0.0220 0.0358 0.0512 20 O. paucilepis 0.0981 0.0992 0.0943 0.1008 0.0878 0.0992 0.0959 0.0943 0.1033 21 O. bergianus 0.1187 0.1203 0.1106 0.1163 0.1057 0.1098 0.1114 0.1203 0.1154 0.1008 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 9’2-10% branched rays, outer margin straight or slightly concave. Anal fin with 5’4 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, out- er 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 denti- formis narrow and rounded. Lower jaw rounded, without median notch. Barbels long; inner rostral barbel reaching base of maxillary barbel, outer reaching to vertical of pos- terior of anterior eye margin. Maxillary barbel reaching or almost reaching to vertical of posterior eye-margin. Coloration. Body with yellowish or cream_back- ground and dark-brown pattern in live and preserved in- dividuals. Preserved individuals with a dark-grey, narrow inner-axial stripe, absent in life. Dorsal head and upper zse.pensoft.net 462 Kaya, C. et al.: Oxynoemacheilus chaboras, a new loach species from the Euphrates drainage Figure 2. Oxynoemacheilus chaboras, FFR 15646, holotype, 53 mm SL; Turkiye: stream Beyazsu. part of cheek brown, with marbled pattern. Ventral sur- face 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 pre- dorsal 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, 7). Etymology. The species is named Chaboras, an an- cient Greek name of the Khabur (XaBapac), as it was zse.pensoft.net first documented by Ptolemy and Pliny the Elder ichthyo- fauna. A noun in genitive, indeclinable. Discussion Following our molecular analysis, Oxynoemacheilus chaboras belongs to the O. persa species group as de- fined by Freyhof and Geiger (2021). Within the O. persa species group, O. chaboras belongs to a group of spe- cies (O. argyrogramma, O. euphraticus, O. hanae, O. karunensis, O. kurdistanicus, O. marunensis, O. persa, O. sarus, and O. shehabi) that have a deeply emarginate or forked caudal fin (vs. slightly emarginate or truncate in O. chomanicus, O. kentritensis, O. zagrosensis, and O. zarzianus) and in which the male has a suborbital groove (vs. absent in O. chomanicus, O. kentritensis, O. zagro- sensis, and O. zarzianus). Oxynoemacheilus chaboras is most closely related to O. shehabi from the upper Orontes, O. sarus from the Sey- han and Ceyhan, O. euphraticus from the Euphrates and Zoosyst. Evol. 100 (2) 2024, 457-468 463 Figure 3. Oxynoemacheilus chaboras, paratypes, stream Beyazsu. a. FFR 1428, 50 mm SL; b. FFR 15633, 51 mm SL; ¢. FFR 1428, 50 mm SL; d. FFR 1428, 49 mm SL. J a AS So Saws | Figure 4. Oxynoemacheilus chaboras, FFR 15633, paratype, 51 mm SL; Turkiye: stream Beyazsu. Tigris, O. karunensis from the Karkheh, and O. persa from — our molecular analysis (Table 1), their phylogenetic relation- Central Iran. Oxynoemacheilus argyrogramma, O. hanae, — ships are poorly supported in our phylogenetic tree (Fig. 1). O. kurdistanicus, O. marunensis are placed in a second clus- Oxynoemacheilus chaboras is distinguished from ter of species within the O. persa species group and are not O. shehabi and O. sarus by possessing 8—9 pores in the closely related. While all these species are well-supported in — supraorbital canal (vs. 5—7), a rudimentary and shallow zse.pensoft.net 464 Kaya, C. et al.: Oxynoemacheilus chaboras, a new loach species from the Euphrates drainage Figure 5. Oxynoemacheilus species in the Euphrates drainages: a. O. bergianus, stream Sason, 61 mm SL; b. O. argyrogramma, stream Stinnep, 50 mm SL; ¢. O. euphraticus, Great Zap River, 55 mm SL; d. O. muefiti, Murat River, 69 mm SL; e. O. tigris, stream Stnnep, 55 mm SL; f. O. kaynaki, Goksu River, 68 mm SL; g. O. paucilepis, stream Baliklitohma, 70 mm SL; h. O. arsaniasus, stream Kaleli, 90 mm SL; i. O. araxensis, stream Arkagayirlar, 71 mm SL. pelvic axillary lobe fully attached to the body (vs. well-de- veloped with a free tip), a deeper body (body depth at dorsal fin origin 17-22% SL vs. 14-17 in O. shehabi), deeper caudal peduncle (10-12% SL vs. 8-9 in O. sheha- bi), deeper head (head depth at eye 51-60% HL vs. 44—51 in O. sarus) and a longer anal fin (anal-fin height 18-22% SL vs. 16-19 in O. sarus). It is distinguished from O. hanae by lacking isolated patches of dark-brown spots or blotches on the lower part of the flank (vs. present) and possessing two distinct black blotches at the caudal-fin base (vs. usually absent or very small, overlaid by a chev- ron shaped bar). The new species is distinguished from O. karunensis and O. persa by lacking the dense mottling in the inter- spaces between the blotches on the flank in almost all in- dividuals (vs. very dense mottling in all individuals), pos- sessing a deeper caudal peduncle (caudal peduncle depth 1.4—1.7 times in its length vs. 1.7—3.1 in O. karunensis), and two distinct black blotches at the caudal-fin base (vs. two very large blotches, usually fused to an irregularly shaped bar in O. persa). zse.pensoft.net We were not able to compare O. chaboras to O. marunensis as we had no materials available. We noted that the description of this species by Sayyadza- deh and Esmaeili (2020) is solely based on juvenile individuals. This limitation made it impossible to make definitive statements about the adult colour pattern and some other character states of O. marunensis. Oxynoe- macheilus chaboras 1s distinguished from O. marun- ensis, based on Sayyadzadeh and Esmaeili (2020), by possessing a deeper body (body depth at dorsal-fin ori- gin 17-22% mm SL vs. 14—18), a narrower interorbital width (18-24% mm HL vs. 23-31), and 9+8 branched caudal-fin rays (vs. 8+7 or 8+8). It should be noted that O. marunensis 1s only distantly related to O. chabo- ras. The mean genetic distance between these species is 4.55%. Oxynoemacheilus chaboras is distinguished from O. kurdistanicus by possessing no, or rarely, a very short incision in the upper lip (vs. usually a deep, rarely a shal- low median incision), and a series of mid-lateral blotch- es disconnected from the saddles on the back below the Zoosyst. Evol. 100 (2) 2024, 457-468 a [_] Tigris drainage . [] Karkeh drainage Karun drainage Ae ia 465 Figure 6. Distribution map of Oxynoemacheilus chaboras and O. euphraticus. Table 2. Morphometric data of Oxynoemacheilus chaboras (holotype FFR 15646 and paratypes FFR 1428, n= 11). Holotype min max mean SD Standard length (mm) 53 46 60 51.9 4.0 In percent of standard length Head length 24.2 23.0 25.0 24.1 0.6 Body depth at dorsal-fin origin 18.4 17.4 21.8 18.8 1.2 Predorsal length 50.9 47.4 51.1 49.7 1.2 Postdorsal length 35.8 33:8°37-4— 3519. 21-2 Prepelvic length 51.2 49'6°55:58. “52.1 1.2 Preanal length LORY: 72.7 78.7 75.7 1.8 Distance between pectoral and 30.1 26.2 30.6 28.4 1.6 pelvic-fin origins Distance between pelvic and 21.4 21.4 25.2 22.8 1.0 anal-fin origins Distance between vent and anal- 3.0 Zot 237i" 82.9 BOYD fin origin Dorsal-fin height 22.7 19.9 24.3 224 1.2 Anal-fin height 18.9 15:8 19:2 17.9 1.0 Pectoral-fin length 24.1 21.8 26.7 24.2 1.7 Pelvic-fin length 18.7 16.5 19.3 18.1 08 Length of caudal peduncle 19.8 16.9 19.8 18.2 0.9 Depth of caudal peduncle 11.9 10.2 12.2 11.6 0.5 In percent of head length Head depth at eye 51 Dla” OOF IT 5389s 2-373 Maximum head width 59 59 66 63.2 2.6 Snout length 40 39 44 414 1.8 Eye diameter 19 19 23 206 1.4 Postorbital distance 45 40 50 45.2 2.7 Interorbital width 21 18 24 21.6 2.3 Length of inner rostral barbel 30 20 30 24.7 2.5 Length of outer rostral barbel 41 34 44 38.5 3.2 Length of maxillary barbel 40 33 44 39.6 3.3 dorsal-fin origin (vs. bars connected to saddles in most, but not all individuals). All O. kurdistanicus examined have a pattern of bars on flank, while most O. chaboras have a series of mid-lateral blotches usually narrowly connected to saddles. In O. chaboras, this pattern is usu- ally formed by two wide and dark elements (blotch and saddle) connected by a narrower and paler field of pig- ments while in O. kurdistanicus (and O. euphraticus and O. marunensis), bars are usually (not always) regularly shaped and not wider along the lateral midline. Comparative materials Oxynoemacheilus araxensis ZMH 4827, holotype, 61 mm SL; ZMH 4826, paratypes, 5, 36-50 mm SL; ZMH 5951, paratypes, 4, 44-64 mm SL; Turki- ye: Erzurum prov.: Kandili Karasu, Euphrates drain- age.—FFR 1354, 11, 66-90 mm SL Turkiye: Erzurum prov.: stream Sirli at Ilica 40.2130°N, 41.0699°E — FFR 1451, 2, 68-75 mm SL; Turkiye: Erzurum prov.: stream Agarcik at Ilica, 40.2460°N, 41.0710°E.—FFR 1468, 12, 53-70 mm SL; Turkiye: Erzurum prov.: stream Bas about 1 km west of Cayk6y, 39.9470°N, 40.8040°E—FSJF 3440, 6, 42-71 mm SL; Turkiye: Erzurum prov.: stream Arkagayirlar at Pasayurdu, 39.9833°N, 40.9920°E. Oxynoemacheilus argyrogramma FFR_= 15516, 26, 37-49 mm SL; Turkiye: Kilis prov.: stream Sunnep at zse.pensoft.net 466 Kaya, C. et al.: Oxynoemacheilus chaboras, a new loach species from the Euphrates drainage a On N ee = a Ee, ee Figure 7. Type locality of Oxynoemacheilus chaboras. northeastern Ktpltice, 36.7640°N, 37.2540°E—FFR 1574, 14, 41-62 mm; FFR 1448, 11, 37-48 mm SL; Turkiye: Gaziantep prov.: stream Merziman about 3 km south of Yavuzeli, 37.2910°N, 37.5730°E. Oxynoemacheilus arsaniasus FFR 15531, paratypes, 5, 36-54 mm SL; Turkiye: Mus prov.: stream Kaynarca at Tepe, 39.1070°N, 41.4920°E.—FFR 1449, 1,49 mm SL; Turkiye: Mus prov.: stream Kaynarca about 3 km southeast Tepe, 39.0680N, 41.5290°E.—FSJF 4019, 12, 46-97 mm SL; Turkiye: Bitlis prov.: Reservoir of stream Karasu in Kaleli, 38.5537°N, 42.0257°E. Oxynoemacheilus bergianus FFR 1577, 19, 54-62 mm SL; Turkiye: Samsun prov.: stream Soruk 20 km east of Vezirkopri, 41.1189°N, 35.2269°E—FFR 15561, 9, 35-69 mm SL; Turkiye: Kayseri prov.: stream Sarnaz a drainage of stream Zamanti at Tas¢1, 38.1953°N, 35.7805°E.—FSJF 2983, 15, 38-77 mm SL; Turkiye: Kayseri prov.: stream Zamanti at Pinarbasi, 38.7366°N, 36.4131°E. —FFR 1457, 11, 64 —72 mm SL; Turkiye: Malatya prov.: stream Sultansuyu 8 km east of Akcadag, 38.3388°N, 38.0620°E.—FFR 1467, 28, 54-64 mm SL; Turki- ye: Erzurum prov.: stream Bas 10 km east of Askale, 39.9478°N, 40.8040°E.—FFR 15506, 25, 33-59 mm SL; Turkiye: Agr prov.: Murat River 17 km west of Tashicgay, 39.6785°N, 43.1887°E. Oxynoemacheilus chomanicus FSJF 3644, 5, 33-61 mm SL; Iraq: Choman River at Alut, 35.9563°N, 45.6155°E. Oxynoemacheilus euphraticus FFR 1434, 1, 56 mm SL; Turkiye: Sivas prov.: Euphrates at Ilic, 39. 4850°N, 38.5850°E.—FFR 1471, 25, 27-63 mm SL; Turkiye: Sivas prov.: stream Kangal about 1 km west of Cetinkaya, 39.2560°N, 37.6250°E.— FFR15520, 14, 41-57 mm SL; Malatya prov.: stream Sultan Suyu about 7 km east of Akcada§g, 38.3390°N, 38.0620°E.—FFR 15508, 13, 53-70 mm SL; Turkiye: Adtyaman prov.: stream Goksu at Diizbag, 37.7950°N, 37.4710°E. zse.pensoft.net Additional distribution records Own data: 39.9124°N, 40.8540°E. 39.9094°N, 40.8028°E. 36.943333°N, 44.19533°E. 39.2516°N, 37.6189°E. 38.9500°N, 40.0166°E. 38.9166°N, 41.2666°E. S92 INe PSO IeES. ASOD IN:. Ade OlSosk: BOQSIS Ns, eSZ618945E, ~“39:25)5SN;. (37.6189°E: BS 916IIN. “4h2067°R, 393013°N) -39:6743°ER:, BP83702N,. 37:6848°E, 39:1439°N, 37.2571°E: 39.2516°N, 37-6189°E,. 36.9433°N;, 44,1953SE: 37.7950°N, 37.4705°E. 37.8444°N, = 37.6702°E. 37.6500°N, 39.0500°E. 37.0666°N, 37.9500°E. 39.9833°N, 40.9920°E. 36.7484°N, 44.2997°E. 36.9433°N, 44.1953°E. 36.6164°N, 44.8781°E. 36.6106°N, 44.8381°E. Saygun et al. (2021): 37.8369°N, 37.6848°E. 39.0956°N, 41.5054°E. —39.4850°N, SS O80°Rs 389 23561" N 3 O2515E: 39 2463°Ne 37.5807°E. 37.9409°N, 38.6470°E. 37.8391°N, 37.6977E. 37.7052°N, 37.4790°E. 37.5021°N, 37.4108°E. Cicek et al. (2022): 39.7800°N, 40.4486°E. Rakici et al. (2020): 39.0741°N, 41.5195°E. 38.6928°N, 41.7142°E. 39.2672°N, 37.4748°E. 38.3471°N, = 38.0737°E. 37.8392°N, 37.6766°E. 37.9635°N, 38.6624°E. Krupp (1985): 37.1006°N, 37.8758°E. 37.6742°N, 39.0158°E. Jouladeh Roudbar et al. (2016): 33.1382°N, 49.6788°E. 33.1182°N, 49.6676°E. 33.7846°N, 48.2068°E. 33.7820°N, 48.2080°E. 33.5507°N, 49.0207°E. 33.0108°N, 49.6478°E. 33.0674°N, 49.6500°E. 33.0559°N, 49.6701°E. 32.9988°N, 49.5823°E. 33.7543°N, 46.6847°E. 34.3478°N, 47.9885°E. Za- re-Shahraki et al. (2022): 33.5647°N, 48.9855°E. 33.3783°N, 49.3888°E. 33.0819°N, 49.6319°E. 33.0570°N, 49.6668°E. 32.8860°N, 49.6560°E. 32.9997°N, 49.5888°E. 33.0322°N, 49.6564°E. Musa and Abdulrahman (2023): 36.6705°N, 44.71154°E. 36.6553°N, 44.9055°E. 36.6325°N, 44.8884°E. Oxynoemacheilus hanae ZFMK 103020, holotype, 57 mm SL; FSJF 3359, paratypes, 22, 46-61 mm SL; Iraq: stream Zalm south of Taparezina, 35.3064°N, 45.9705°E.—FSJF 3641, 63, 34-61 mm SL; Iraq: stream Zalm south of Taparezina, 35.3064°N, 45.9705°E. Oxynoemacheilus karunensis FSJF 3525, 8, 33-55 mm SL; Iran: Hamadan prov.: Gamasiab River at Do Ab, 47. 9167°N, 34.3724°E.—FSJF 3523, 6, 34-51 mm SL; Iran: Hamadan prov.: Haram Abad River at Ashmizan, 34.1105°N, 48.8704°E.—FSJF 3524, 7, 37-53 mm SL; Hamadan prov.: Dehno stream about 2 km south-west of Nahavand, 48.3532°N, 34.1691°E—FSJF 3526, 2, 30-40 mm SL; Iran: Hamadan prov.: Gamasiab River at Chesme Mahi, 34.3382°N, 48.0324°E——SMEF IR7, 3, 36-44 mm SL; Iran: Khozestan prov.: Marun River near Behbehan, 30.6567°N, 50.1883°E. Oxynoemacheilus kentritensis FFR 1566, holotype, 67 mm SL; Turkiye: FFR 01403, paratypes, 3, 57-68 mm SL; Bitlis prov.: stream Kesan about 1 km south of Guntepe, 38.3566°N, 42.6275°E.—FSJF Zoosyst. Evol. 100 (2) 2024, 457-468 3645, paratypes, 3, 65-79 mm SL; Turkiye: Bitlis prov.: stream Horozdere east of Hizan, 38.2447°N, 42.4791°E—FSJF 3646, paratypes, 2, 68-70 mm SL; Turkiye: Bitlis prov.: stream Oraniz about 1 km east of Donertas, 38.3141°N, 42.5655°E. Oxynoemacheilus kurdistanicus FSJF 3369, 28, 40-61 mm SL; Iraq: Nalparez River, 35.5707°N, 45.8630°E.—FSJF 3347, 25, 50-62 mm SL; Iraq: stream north-west of Saburawa, a tributary of Tabin River, 35.8336°N, 45.1044°E—FSJF 3353, 9, 40-61 mm SL; Iraq: stream KunaMassi in Sevanja, 35.7892°N, 45.4030°E.—FSJF 3373, 54, 35-62 mm SL; Iraq: stream Suraw near Suraw village, 35.7626°N, 45.9848°E.—FSJF 3643, 15, 36-62 mm SL; Iraq: Choman River at Alut, 35.9564°N, 45.6155°E. Oxynoemacheilus muefiti FFR 15507, paratypes, 2, 29— 45 mm SL; Aéri prov.: Turkiye: Murat River at Balli- bostan; 39.6780°N, 43.1890°E.—FFR 1432, 7, 42-63 mm SL, Air prov.: Turkiye: Murat River at Taslicay; 39.6460°N, 43.3670°E.—FSJF 3444, 4, 33-46 mm SL; Turkiye: Ar prov.: Murat River at Ballibostan, 12 km east of Agri, 39.6789°N, 43.1896°E.—FSJF 2556, 3, 45-47 mm SL; Turkiye: Adiyaman prov.: stream Egri south of Adiyaman, tributary to Atatiirk Reservoir, 37.7417°N, 38.3351°E—IUSHM 2019- 1410, 3, 37-68 mm SL; Turkiye: Agri prov.: stream near Sarikoy, 16 km west of Eleskirt, 39.8016°N, 42.4816°E—IUSHM 2019-1411, 3, 43-52 mm SL; Turkiye: Agri prov.: Murat River at Balibostan, 12 km east of Agri, 39.6789°N, 43.1896°E. Oxynoemacheilus paucilepis FFR15510, 10, 34-73 mm SL; Turkiye: Sivas prov.: stream Baliklitohma about 3 km south of Kocakurt, 39.1440°N, 37.2570°E— FFR15521, 15, 41-76 mm SL; Turkiye: Sivas prov.: stream Baliklitohma at Kuruayse, 39.2070°N, 37.2010°E.—FSJF 2852, 50, 24-39 mm SL; Turkiye: Sivas prov.: stream Tersakan about 15 km southwest of Kangal, 39.1439°N, 37.2571°E. Oxynoemacheilus persa NMW 48567, holotype, 50 mm SL; Iran: spring at Persepolis—FSJF 3214 (earlier IZA 7826), 25 paratypes of O. farsicus, 34-56 mm SL; Iran: Fars prov.: Shur River at Dasht-e-Arzhan, a tributary of Mond River.— FSJF 2245, 44, 31-65 mm SL; Iran: Fars prov.: Kor River about 73 km north of Shiraz, 30.1936°N, 52.4657°E. Oxynoemacheilus sarus FFR 15585, holotype, 52.5 mm SL; FFR 15522, paratypes, 4, 39-54 mm SL;Turki- ye: Adana prov.: lower stream Cakit, south of Salbas, 37.1031°N, 35.1094°E.—FSJF 2327, paratypes, 10, 32-49 mm SL; Turkiye: Adana prov.: lower stream Cakit, south of Salbas, 37.0961°N, 35.1170°E— FSJF 2377, paratypes, 2, 48-49 mm SL; Turkiye: Adana prov.: stream Korktin at Karakuyu, 37.1529°N, 35.1606°E.—FFR 15586, 3, 47-51 mm SL; Turkiye: Kahramanmaras Prov.; stream Aksu at 8 km northeast of Pazarcik, 37.5390°N, 37.3480°E.—FSJF 2567, 1, 48 mm SL; Turkiye: Adiryaman prov.: stream Celik at road south of Gélbas1, 37.6239°N, 37.5034°E. 467 Oxynoemacheilus shehabi ZFMK ICH 124181, holo- type, 46.3 mm SL; ZFMK ICH-125126-28, paratypes, 3, 41.5-47.6 mm SL; Syria: Orontes at Al Qusayr, 34.5086°N, 36.5389°E. Oxynoemacheilus zarzianus FSJF 3352, 28, 39-69 mm SL; Iraq: stream Kunamasi in Sevanja, 35.7892°N, 45.4030°E—FSJF 3348, 16, 46-68 mm SL; Iraq: stream in Merga village, 36.0515°N, 45.0945°E — FSJF 3651, 18, 54-75 mm SL: Iraq: stream Kunamasi in Kunamasi, 35.7967°N, 45.4136°E—FSJF 3372, 30, 43-71 mm SL; Iraq: stream Suraw near Suraw vil- lage, 35.7626°N, 45.9848°E. Acknowledgments Authors would like to thank Fadil Kaya (Bitlis) for his help during the fieldwork. We also thank Mufit Ozu- lug (IUSHM), Anja Palandacic (NMW), Serkan We- sel (ZFMK-ICH), and Ralf Thiel (ZMH) for allowing JF to examine materials under their care. Because the second author contributed to this manuscript at Bour- nemouth University, we would like to thank Bour- nemouth University for providing their facilities, and TUBITAK BIDEB (2219 Program) which supported her with one-year scholarships during her post-doc re- search at United Kingdom. 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