A practical approach to revise the Oxynoemacheilus bergianus species group (Teleostei: Nemacheilidae) Author Freyhof, Jörg 0000-0002-7042-3127 Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, 10115 Berlin, Germany. joerg. freyhof @ mfn. berlin; https: // orcid. org / 0000 - 0002 - 7042 - 3127 joerg.freyhof@mfn.berlin Author Kaya, Cüneyt Recep Tayyip Erdogan University, Faculty of Fisheries, 53100 Rize, Turkey. Author Geiger, Matthias F. 0000-0003-2403-0805 Zoological Research Museum Alexander Koenig, Leibniz Institute for Animal Biodiversity, Adenauerallee 160, 53113 Bonn, Germany. m. geiger @ leibniz-zfmk. de; https: // orcid. org / 0000 - 0003 - 2403 - 0805 m.geiger@leibniz-zfmk.de text Zootaxa 2022 2022-04-20 5128 2 151 194 journal article 55850 10.11646/zootaxa.5128.2.1 de62b63c-58f4-4a92-b41b-e66c9e90a36a 1175-5326 6479752 17900DD5-DFEB-43D8-BBBB-DB60C74730FB Oxynoemacheilus fatsaensis Saygun, Ağdamar & Özuluğ, 2021 ( Fig. 12–14 ) Oxynoemacheilus fatsaensis Saygun, Ağdamar & Özuluğ, 2021:41 , fig. 2–4. ( type locality: Turkey : Ordu prov. : stream Elekçi , 40.5320N 37.2339E ). Material examined. FFR 1361, 5, 46–58 mm SL; Turkey : Samsun prov: stream İlhanlı at Ayvacık , 40.990N 36.634E .— FFR 1362 , 10 , 37–64 mm SL; Turkey : Giresun prov: stream Aksu at Dereli , 40.731N 38.460E .— FFR 1362 , 10 , 37–64 mm SL; Turkey : Tokat prov: stream Kelkit 9 km north of Erbaa , 40.759N 36.515E .— FFR 1516 , 31 , 38–75 mm SL; Turkey : Samsun prov. : stream Tersakan 4 km west of Havza , 40.989N 35.717E .— FSJF 3128 , 2 , 60–62 mm SL; Turkey : Amasya prov. : Yeşilırmak at Ilıcasu , 15 km west of Taşova , 40.736N 36.150E .— FSJF 3174 , 16 , 33–59 mm SL; Turkey : Amasya prov. : Yeşilırmak at Taşova , 40.758N 36.328E .— FSJF 3176 , 17 , 29–63 mm SL; Turkey : Amasya prov. : stream Çorum 15 km north of Göynücek , 40.8217N 35.9864E . Material used in molecular genetic analysis. FSJF DNA-1621 ; Turkey : Amasya prov. : stream Çorum 15 km north of Göynücek , 40.8217N 35.9864E (GenBank accession: OK 316631 , OK 316713 , OK 316702 ) . Distribution. Oxynoemacheilus fatsaensis was found in the coastal stream Elekçi in northern Anatolia and is widespread in tributaries of the adjacent Yeşilırmak River drainage. See Fig. 2 for the distribution of this species. Remarks. Oxynoemacheilus fatsaensis is distinguished from other species of the O. bergianus group by a minimum K2P distance of 3.2% to O. simavicus from the Sakarya and Büyük Melen, also supported as PTP, mPTP and ASAP entity/entities. We were not able to examine O. fatsaensis from the stream Elekçi, the type locality of the species. Individuals from the Yeşilırmak are distinguished by a minimum K2P distance of 0.7% from those from the Elekçi and are treated as conspecific. Saygun et al . (2021) also examined fishes from the Yeşilırmak and identified these as O. cf. banarescui . But in their morphological analysis, they did not distinguish O. fatsaensis from their O. cf. banarescui , but only from O. banarescui . Saygun et al . (2021) distinguish O. fatsaensis from O. bergianus by having a flank pattern that is irregularly mottled (vs. irregularly shaped bars or small blotches anteriorly mottled in some individuals), shorter postorbital distance (39.8–44.1% HL, vs. 43.1–45.7%), a deeper caudal peduncle (depth 9.4–10.1% SL, vs. 7.3–9.5), and a suborbital flap that extends forward to the mid-length of the posterior nostril (vs. reaches forwards to the front of the posterior nostril). In our materials, O. bergianus with a mottled flank pattern occur in many populations, while indeed most individuals have a blotched pattern. The postorbital distance is 39–48% HL in our O. bergianus , the caudal peduncle is 7–10% SL and we found no difference in how far the suborbital flap reaches beyond the posterior nostril. FIGURE 12. Oxynoemacheilus fatsaensis , FFR 15513, 55 mm SL; FFR 01566, 74 mm SL, 67 mm SL; Turkey: stream Tersakan. FIGURE 13. Oxynoemacheilus fatsaensis , FSJF 3176, 63 mm SL; Turkey: stream Çorum. Saygun et al . (2021) distinguish O. fatsaensis from O. banarescui and “ O. samanticus ” (= O. bergianus from the Kızılırmak) by having an irregularly mottled flank pattern (vs. 6–8 large blotches in O. banarescui ; 6–9 in “ O. samanticus ” ), a deeper caudal peduncle (depth 9.4–10.1% SL, vs. 7.6–9.2 in O. banarescui ; 7.2–9.3 in “ O. samanticus ” ), a deeper caudal peduncle (its depth 1.9–2.1 times in its length, vs. 2.0– 2.7 in O. banarescui ; 2.2–2.8 in “ O. samanticus ” ), the pelvic fin that is not reaching beyond anus (vs. reaching in “ O. samanticus ” ), the pelvic-fin origin that is located below the first branched dorsal-fin ray (vs. first or second branched dorsal-fin ray in O. banarescui ), a short inner rostral barbel, not reaching base of maxillary barbel (vs. reaching, with the exception of a few O. banarescui samples not reaching), and 5–6 dark-grey saddles on back posterior to dorsal-fin base (vs. 2–3 in O. banarescui , 3–4 in “ O. samanticus ” ). In our materials, O. banarescui and O . bergianus from the Kızılırmak (=“ O. samanticus ”) with a mottled flank pattern are common in many populations of both species and we also found several O. fatsaensis with lateral blotches in our materials. The caudal peduncle depth of our specimens is 7–11% (1.6–2.9 times in its length) in O. banarescui and 6–9% (2.2–3.5 times in its length) in “ O. samanticus ” and 8–9% SL (2.0–2.6 times in its length) in O. fatsaensis from the Yeşilırmak. The pelvic fin is not reaching beyond anus in many individuals of “ O. samanticus ” and the pelvic-fin origin is located below the first or second branched, often below the last unbranched dorsal-fin ray in “ O. samanticus ” as well as in in O. fatsaensis from the Yeşilırmak. We also found no difference in the length of the barbels or in the number of saddles on the back behind the dorsal-fin base. All these values largely overlap with those given by Saygun et al . (2021) Saygun et al . (2021) distinguish O. fatsaensis from O. simavicus by having an irregularly mottled flank pattern (vs. 8–9 mid-lateral blotches along the lateral line), a greater distance between the pelvic and anal-fin origins (20.9– 23.5% SL vs. 19.9–21.6), and a deeper caudal peduncle (its depth 1.9–2.1 times in its length, vs. 2.1–2.6). In our materials, O. simavicus with a mottled flank pattern are common, including those from the Simav drainage as well as the Sakarya and in O. fatsaensis from the Yeşilırmak, individuals with mid-lateral blotches occur together with mottled individuals as in most populations of species of the O. bergianus group. We found the distance between the pelvic and anal fin origins 20–22% SL in O. simavicus from the Simav and 19–23 % SL in the Sakarya and 20–23% SL in O. fatsaensis from the Yeşilırmak. The caudal peduncle depth is 2.2–2.9 times in its length in our O. simavicus from the Simav, 1.6–3.0 in O. simavicus from the Sakarya and 2.0– 2.6 in O. fatsaensis from the Yeşilırmak. All together, we were unable to support any of the characters given by Saygun et al . (2021) to distinguish O. fatsaensis from other species of the O. bergianus group. However, in contrast to O. longipinnis , O. parvinae and O. samanticus , O. fatsaensis is much stronger differentiated from O. bergianus (as recognised herein including “ O. erdali ”, “ O. lenkoranensis ”, “ O. longipinnis ”, “ O. parvinae ”, “ O. samanticus ”, O. sp. Tigris) based on COI data, from which it is distinguished by a K2P distance of 3.8%. We treat O. fatsaensis as a valid species indistinguishable from the other species of the same group by the morphological characters studied so far.