Oxynoemacheilus fatsaensis Saygun, Agdamar & Ozulug

3.1. Oxynoemacheilus fatsaensis Saygun, Agdamar & Ozulug ¨ sp. nov

( Figs. 2 View Fig – 5 and Table 4 View Table 4 ).

3.1.1. Material examined

Holotype. IUSHM 2021 – 1449 , 77 mm SL; Turkey: Ordu prov.: Stream Elekçi , 40.53200N 37.23390E; S. Saygun, 26 October 2020 GoogleMaps .

Paratypes. IUSHM 2021 – 1450 , 6, 64 – 75 mm SL; same data as holotype; GoogleMaps IUSHM 2021 – 1451 , 8, 63 – 73 mm SL; Turkey: Ordu prov.: Stream Elekçi , 40.53200N 37.23390E; S. Saygun, 30 August 2018 GoogleMaps .

The material used in molecular genetic analysis. IUSHM 2021- 1450DNA; same data as holotype.

3.1.2. Diagnosis

O. fatsaensis is distinguished from other species ( O. angorae , O. banarescui , O. cemali , O. seyhanensis , O. samanticus , O. simavicus ) know from the Black Sea basin of Anatolia by a combination of characters, none of which are unique. It is distinguished from O. angorae , by having an axillary lobe at the pelvic-fin base (vs. absent), a deeply emarginate caudal-fin (vs. emarginate), a flank pattern that is irregularly mottled (vs. a series of fused mid-lateral blotches, forming a lateral stripe in most individuals), 3 – 7 irregularly shaped saddles on the back, anterior to the dorsal-fin origin (vs. absent), a short, inner rostral barbel, not reaching the base of maxillary barbel (vs. reaching) and a slender caudal peduncle (depth 9.4 – 10.1% SL, vs. 10.5 – 11.24).

3.1.3. Description

See Figs. 2 View Fig – 5 for general appearance and Table 4 View Table 4 for morphometric data of O. fatsaensis , new species. Body slender and compressed laterally at the caudal peduncle. Head long, body depth at dorsal-fin origin 1.2 – 1.6 times of the head length. Body deepest at the midpoint of dorsal-fin origin and nape. Body width the greatest at the pectoral-fin base. Section of head roundish, flattened on the ventral surface. Snout roundish. There is no hump at nape. Caudal peduncle compressed laterally and 1.9 – 2.1 times longer than deep. A rudimentary pelvic axillary lobe present. The pelvic-fin origin below the first branched dorsal-fin ray. The anal-fin origin anterior to the vertical midline between dorsal-fin and caudal-fin origins. Pectoral-fin reaching to approximately 65 – 95% of the distance from the pectoral-fin origin to pelvic-fin origin; not reaching to the vertical through of dorsal-fin origin. Pelvic-fin usually reaching to genital papillae. Anal-fin not reaching the caudal-fin base. There is no adipose crest on the caudal peduncle. The largest known individual is 77 mm SL.

Dorsal-fin with 7½ – 8½ branched rays, outer margin straight or slightly concave. Anal-fin with 5½ branched rays, the outer margin is slightly concave. Pectoral-fin has 10 – 12 (mode 10) rays. Pelvic-fin with 7 – 8 (mode 8) rays. Caudal-fin deeply emarginate. Caudal-fin with 9 – 8(1), 8 + 8(12), 8 – 7(1) branched rays. Flank and dorsum covered by scales. Chest and belly without scales. Head and flank covered with nuptial tubercles in males. Lateral line complete reaching to the caudal-fin base. Anterior nostril opening at the end of a low pointed, and flap-like tube. Posterior tip of anterior nostril overlapping posterior nostril when folded backward. Males show an exposed lacrimal bone, which is completely attached to the skin. Therefore, we called this a suborbital groove. Suborbital groove in males reaching to half of the posterior nostril. During the breeding period, this suborbital groove is covered with tubercles and for this reason, the ventral margin is not completely attached to the skin ( Fig. 6 View Fig ). Mouth small and narrow and slightly arched. Lips thick without furrows. The lower lip is thicker than the upper one. A median interruption in the lower lip and a median incision in the upper lip. Processus dentiformis narrow. Lower jaw rounded, without a median notch. Inner rostral barbel short, not reaching the base of maxillary barbel. Outer rostral barbel usually reaching vertically through to midpoint of the posterior nostril, and maxillary barbel, reaching vertically through to midpoint of the eye or posterior margin of the eye.

Coloration: Body golden-orange background and dark-brown marbled pattern in live specimens. It has a yellowish background and a dark-brown or grey marbled pattern in preserved individuals. Dorsal head and cheek with a marbled pattern, on the ventral surface of the head. Only the posterior of lower lips and base of the maxillary barbels with distinct brown dots. Flank pattern mottled. In a few of the samples, the caudal peduncle with irregularly shaped dark brown blotches. The back usually with 5 – 6 mostly Xshaped dark brown saddles, posterior to dorsal-fin origin, and 3 – 4 indistinct small bar-shaped saddles anterior to dorsal-fin origin. A dark-brown bar present at the caudal-fin base. Dorsal-fin with small dark brown or black blotches on rays, forming 2 bands. Caudal-fin with small black blotches on rays, forming 2 – 4 distinct bands. Pectoral fin with irregularly black or brown blotches on rays. Pelvic- and anal-fins with few dark brown or black blotches on rays. All fins are light orange in life, yellowish in preserved individuals.

O. fatsaensis is found in the reservoir of a waterfall around an old water mill in the branch flowing into the Elekçi Stream in the K osebucag ¨ ı Village of Fatsa District ( Fig. 1 View Fig ). This is a clear water habitat with relatively less flow compared to the stream and the streambed has a little slope and small moss-covered stones ( Fig. 7. A and B View Fig ). They share this habitat with Crimean barbels ( Barbus tauricus ), Banarescu's Barbels ( Capoeta banarescui ), and Chubs ( Squalius sp. ).

3.1.5. Etymology

The species is named for its type locality, the Fatsa district in the Ordu Province. An adjective.

3.2. DNA barcoding of Oxynoemacheilus

Fig. 8 shows a molecular taxonomic cladogram based on the DNA barcoding fragment of the mitochondrial COI gene of four specimens of the new species, O. fatsaensis , and its closest congeneric species, showing the monophyly of all of them, with good statistical support. The barcodes of the new species exhibit an identical nucleotide sequence and form a cluster that differs from its closest neighbor, O. banarescui , by 3.3% (Table 5). The average congeneric distance of the Oxynoemachelius species used in this research was 9.1%, varying between 1.7% ( O. ercisianus vs O. kaynaki and O. eregliensis vs O. atili ) and 12.4% ( O. ercisianus vs O. brandtii and O. eregliensis vs O. brandtii ).

4. Discussion

O. fatsaensis is distinguished from O. seyhanensis , from the K ı z ı l ı rmak and Yeşil ı rmak basin, by having a suborbital groove in males (vs. lacking), an axillary lobe at the pelvic-fin base (vs. absent), a deeply emarginate caudal-fin (vs. emarginate), a longer caudal peduncle (length 18.6 – 20.2% SL, vs. 15.7 – 18.6), a more slender caudal peduncle (depth 9.4 – 10.1% SL, vs. 12.3 – 14.5), and by lacking a dorsal adipose crest on the caudal peduncle (vs. present).

O. fatsaensis is distinguished from O. banarescui and O. samanticus 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 rays 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 ).

O. fatsaensis is distinguished from O. cemali , from the Çoruh River basin, by having a flank pattern that is irregularly mottled (vs. 9 – 15 irregularly shaped dark-grey bars on the flank posterior to the dorsal-fin origin in most individuals), a slender caudal peduncle (depth 9.4 – 10.1% SL, vs. 10.1 – 12.2), a short inner rostral barbel, not reaching the base of maxillary barbel (vs. reaching), a suborbital groove that extends to half-length of the posterior nostril (vs. reaches the front of the posterior nostril), and black pigments on the ventral side of the head posterior to the lower lips and base of the maxillary barbels with (vs. without pigmentation).

O. fatsaensis in distinguished from O. simavicus , from the Simav River basin, 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 – 23.54% 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).

O. fatsaensis in distinguished from O. phasicus , from Enguri and Rioni River drainages in Georgia, by having a deeply emarginated caudal fin (vs. slightly emarginated), a smaller post dorsal length (34.9 – 38.5% SL vs. 39.1 – 41.0) a longer pelvic fin length (16.1 – 21.7% SL vs. 14.6 – 16.8), a short inner rostral barbel, not reaching to the base of maxillary barbel (vs. reaching), and outer margin of the dorsal fin that is straight or slightly concave (straight or slightly convex).

4.1. Comparison with species in adjacent regions

The type locality of O. fatsaensis is a small and isolated stream flowing into the Black Sea. Two major river basins, Euphrates and Kura-Aras, are close to this region. We distinguish O. fatsaensis from O. cyri , O. brandtii , and O. veyselorum from Kura-Aras river drainage and O. arsaniasus , O. kaynaki , O. mue fi ti, O. argyrogramma , O. paucilepis , O. bergianus , O. araxensis , and O. euphtraticus from Euphrates River drainage.

O. fatsaensis is distinguished from O. cyri from Kura River drainage, by having a suborbital groove in males (vs. lacking), a deeply emarginated caudal fin (vs. emarginate), a longer caudal peduncle (length 18.6 – 20.2% SL, vs. 16.8 – 17.7), a more slender caudal peduncle (depth 9.4 – 10.1% SL, vs. 11.0 – 12.0) and having a flank pattern that is irregularly mottled (vs. 10 – 15 irregularly shaped dark-grey bars on the flank posterior to the dorsal-fin origin in most individuals).

O. fatsaensis is distinguished from O. brandtii from Kura River drainage, by having a flank pattern that is irregularly mottled (vs. 10 – 13 irregularly shaped dark-grey bars on the flank posterior to the dorsal-fin origin in most individuals), a deeper caudal peduncle (depth 9.4 – 10.1% SL, vs. 7.1 – 8.8), and a deeply emarginated caudal fin (vs. forked).

O. fatsaensis is distinguished from O. veyselorum from Aras River drainage, by a deeply emarginated caudal fin (vs. emarginate), a slenderer caudal peduncle (depth 9.4 – 10.1% SL, vs. 10.2 – 11.4), large eye diameter (13.8 – 17.4% HL, vs. 9.6 – 13.7), and shorter inner rostral barbel (not reaching the base of maxillary barbel vs. reaching).

O. fatsaensis is distinguished from O. araxensis by having an irregularly mottled flank pattern (vs. 6 – 9 irregularly shaped dark-grey bars on the flank like a lateral band), a slender caudal peduncle (depth 9.4 – 10.1% SL, vs. 12.3 – 13.2), a short inner rostral barbel, not reaching to the base of the maxillary barbel (vs. reaching), and a deeply emarginated caudal fin (vs. emarginate).

O. fatsaensis is distinguished from O. bergianus by having a flank pattern that is irregularly mottled (vs. irregularly shaped bars or small blotches anteriorly mottled in some individuals), smaller 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 groove that extends to the mid-length of the posterior nostril (vs. reaches the front of the posterior nostril) O. erdali reported from the Upper Murat river basin has been accepted as the junior synonym of O. bergianus and also confirmed with genetic and morphological examinations ( Freyhof et al. 2019). The existence of O. bergianus in the Anatolian inland waters has been confirmed.

O. fatsaensis is distinguished from O. kaynaki and O. paucilepis by having a deeply emarginated caudal fin (vs. emarginate) and a suborbital groove in males (vs. lacking); from O. arsaniasus and O. mue fi ti, by having a complete lateral line (incomplete) and slender caudal peduncle (its depth 1.9 – 2.1 times in its length, vs. 1.3 – 1.6); from O. argyrogramma by having a slender caudal peduncle (its depth 1.9 – 2.1 times in its length, vs. 1.4 – 1.8) and dark-brown bar at the caudal-fin base (vs. having two bold black jet spots).

4.2. Molecular data

The NJ analysis of the COI barcode data resulted in congruent trees constructed with high bootstrap values. In the molecular identification of this putative species employing DNA barcodes, these have proven to define the different species according to traditional taxonomy. The genetic distance value shown by these congeners is among the values described for freshwater fish ( Hubert et al. 2008). The four DNA barcodes obtained from O. fatsaensis specimens are identical to each other and cluster independently of those of the taxonomically closest Oxynoemacheilus species, with genetic distance values typical of an independent species, as the probability of conspecificity declines dramatically with a 2% divergence in fish ( Ward 2009).