Oxynoemacheilus sarus, Freyhof & Yoğurtçuoğlu & Kaya, 2021

Freyhof, Jörg, Yoğurtçuoğlu, Baran & Kaya, Cüneyt, 2021, Oxynoemacheilus sarus, a new nemacheilid loach from the lower Ceyhan and Seyhan in southern Anatolia (Teleostei: Nemacheilidae), Zootaxa 4964 (1), pp. 123-139 : 128-135

Oxynoemacheilus sarus , new species

( Figs 2–5 )

Holotype. FFR 15585, 52.5 mm SL; Turkey: Adana prov.: lower stream Çakıt, south of Salbaş , 37.1031N 35.1094E.

Paratypes. FFR 15522, 4, 39–54 mm SL; same data as holotype.— FSJF 2327 , 10 , 32–49 mm SL; Turkey: Ad- ana prov.: lower stream Çakıt, south of Salbaş , 37.0961N 35.1170E .— FSJF 2377 , 2 , 48–49 mm SL; Turkey: Adana prov.: stream Körkün at Karakuyu , 37.1529N 35.1606E .

Additional material. FFR 15586, 3, 47–51 mm SL; Turkey: Kahramanmaraş Prov.; stream Aksu at 8 km north- east of Pazarcık , 37.5390N, 37.3480E.— FSJF 2567 , 1 , 48 mm SL; Turkey: Adıyaman prov.: stream Çelik at road south of Gölbaşı , 37.6239N 37.5034E .

Material used in molecular genetic analysis. FSJF DNA-318 , Turkey: Adana prov.: lower stream Çakıt, south of Salbaş , 37.0961N 35.1170E (GenBank accession number: KJ553782 ) .— FSJF DNA-1492 ; Turkey: Adana prov.: stream Körkün at Karakuyu , 37.1529N 35.1606E. (GenBank accession number: KJ553976 ) .

Diagnosis. Oxynoemacheilus sarus is distinguished from sympatric O. seyhanicola by possessing narrow, darkbrown bands on the caudal fin (vs. hyaline or with very indistinct brown pigmentation on rays), a black spot at the upper and a black blotch on the lower caudal-fin base (vs. absent, often with a very small black spot in front of the first unbranched caudal-fin rays at the upper and lower caudal-fin base, usually an indistinct central brown blotch or short bar on middle of caudal-fin base), and a series of midlateral blotches on the flank, individual blotches not or very rarely extending to middorsal saddles (vs. flank with bars extending to middorsal saddles and meeting contralaterals in many individuals, in some individuals a series of midlateral blotches, usually overlaid by bars).

Oxynoemacheilus sarus is distinguished from O. evreni , which is found in the lower Ceyhan, by possessing a deeper caudal peduncle (caudal-peduncle depth 1.5–1.8 times in its length vs. 1.8–2.4), a forked caudal fin in which the shortest middle caudal-fin ray is 56–70% of the longest ray in the upper caudal-fin lobe (vs. 80–91%), a black blotch or spot at the upper and lower caudal-fin base (vs. absent), and a midlateral series of irregularly shaped blotches along the flank, usually disconnected from the saddles on the back (vs. flank with irregularly shaped bars or vertically elongate blotches, especially on the caudal peduncle usually connected to the saddles on the back).

Oxynoemacheilus sarus is distinguished from O. cilicicus , O. ceyhanensis , O. samanticus , and O. seyhanensis , the four other species of Oxynoemacheilus known from the Ceyhan and Seyhan, by having a more slender caudal peduncle (caudal-peduncle depth 1.5–1.8 times in its length vs. 1.0– 1.4 in O. cilicicus , 1.2–1.5 in O. seyhanensis , 2.2–3.5 in O. samanticus ), a suborbital groove in the male (vs. absent in O. cilicicus and O. seyhanensis ), a complete lateral line terminating shortly in front of or at the caudal-fin base (vs. incomplete, terminating behind the dorsal-fin base, rarely on the caudal-fin base in some individuals in O. cilicicus ), a forked caudal fin (vs. deeply emarginate in O. cilicicus , slightly emarginate in O. seyhanensis ), a black blotch at the upper and lower caudal-fin base (vs. absent, often with an indistinct central brown blotch on the middle of the caudal-fin base in O. samanticus ), and the flank with a midlateral series of irregularly shaped blotches (vs. flank with irregularly shaped bars, especially on caudal peduncle). It is distinguished from O. ceyhanensis by possessing a slender caudal peduncle (caudal-peduncle depth 1.5–1.8 times in its length vs. 1.3–1.5), a black blotch at the upper and lower caudal-fin base (vs. absent), a forked caudal fin in which the shortest middle caudal-fin ray is 56–70% of the longest ray in upper the caudal-fin lobe (vs. 80–88%), and the flank with a midlateral series of irregularly shaped blotches (vs. flank with irregularly shaped bars, especially on caudal peduncle). See below to distinguish O. sarus from other species of the O. persa species group.

Description. See Figures 2–5 for general appearance and Table 2 for morphometric data. Small-sized and slen- der species. Body deepest at nape or at midpoint of dorsal-fin origin and nape. Body width greatest at pectoral-fin base. Section of head roundish, flattened on ventral surface, slightly convex in interorbital space, convex on snout. Snout blunt. Caudal peduncle compressed laterally, 1.5–1.8 times longer than deep. Pelvic axillary lobe present, fully attached to flank. Pelvic-fin origin below first or second branched dorsal-fin ray. Anal-fin origin at in front of vertical of midline between dorsal and caudal-fin origins. Pectoral fin reaching to approximately 80–90% of distance from pectoral-fin origin to pelvic-fin origin in female, reaching to pelvic-fin origin in male. Pelvic fin reaching anus, or reaching to genital papillae; reaching vertical of tip of last dorsal-fin ray or slightly anterior to that point. Anus about 50–70% 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 54 mm SL.

Dorsal fin with 8½–10½ branched rays, outer margin concave. Anal fin with 5½ branched rays, outer margin straight or slightly concave. Pectoral fin with 9–11 branched rays, outer margin straight. Pelvic fin with 7–8 branched rays, outer margin straight or slightly convex. Caudal fin forked with 9+8 branched rays. Flank and back covered by cycloid scales, scales irregularly set on predorsal back, densely set on predorsal flank below lateral line. Chest and belly without scales. Lateral line complete, terminating between origin of hypural complex and caudalfin 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 or two lateral pore on each side of supratemporal head canal, 4 + 8–11 pores in infraorbital canal, 5–7 pores in supraorbital canal, and 5–9 pores in mandibular canal, often very small. A long 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 with a small and short median incision in two individual, absent in others. Processus dentiformis narrow and rounded. Lower jaw rounded, without median notch. Barbels moderately long; inner rostral barbel reaching or not reaching base of maxillary barbel, outer reach- ing to vertical of posterior nare or anterior eye margin. Maxillary barbel reaching to vertical through centre of eye or posterior eye-margin.

Coloration. Body with yellowish or pale brown background and dark-brown pattern in live and preserved individuals. Preserved individuals with a dark-grey, narrow inner-axial stripe especially prominent on flank behind dorsal-fin base, absent in life. Dorsal head and upper part of cheek with a vermiculate or marbled pattern, cheek without pattern in some individuals. Ventral surface of head yellowish without pattern. Flank with 7–12 dark-brown, irregularly shaped and set midlateral blotches, connected by inner axial stripe in preserved individuals. Blotches not or rarely extending to middorsal saddles. Midlateral blotches usually dissociated on predorsal part of flank. Back with 2 predorsal saddles, one saddle at dorsal-fin origin and one at posterior dorsal-fin base, a single individual with 3 predorsal saddles, and 2–4 saddles behind dorsal fin, all saddles wider than interspaces. No or few spots, vermiculation or mottling between blotches on back and flank above lateral midline. One dark-brown, often commashaped blotch at lower caudal-fin base usually reaching to middle of caudal-fin base, a second, much smaller blotch at uppermost caudal-fin base, both indistinct in some preserved individuals. Posteriormost upper and lowermost caudal peduncle without a distinct yellowish, unpigmented blotch. Dorsal and pectoral fins with many, small brown blotches on rays, forming 1–3 narrow bands. Caudal fin with many small brown blotches on rays, forming 3–6 very distinct bands. Dorsal, caudal and pectoral fin greyish. Anal and pelvic fins hyaline in life, yellowish in preserved individuals, with few dark-brown blotches on rays.

Distribution. Oxynoemacheilus sarus was collected from the lower Ceyhan and Seyhan drainages in Turkey.

Etymology. The species is named for the Sarus, the Roman name of the Seyhan River. A noun in the genitive.

Remarks. In the Seyhan River drainage, O. sarus occurs in sympatry and even in syntopy with O. cilicicus and O. seyhanicola , and in the Ceyhan it might occur in sympatry with O. cilicicus , O. seyhanicola and O. evreni . While O. cilicicus is a deep-bodied species with an incomplete lateral line, bars on the flank, and lacking the suborbital groove ( Kaya et al. 2020), O. sarus is superficially similar to O. evreni and O. seyhanicola by possessing a slender body, a complete lateral line, a series of midlateral blotches, and a suborbital groove.

Oxynoemacheilus seyhanicola was described by Erk’akan et al. (2007) based on a single individual ( Fig. 6 ) from “Dam bridge near Adana, Seyhan basin, 38°39′N 36°37′E ”, where the type locality is exactly remains unclear. The coordinates in the original description are obviously incorrect, which are the same as for the holotypes of O. evreni and O. ceyhanensis , although the localities are different. Füsun Erk’akan told us that she does not well re- member the exact place, but likely the holotype was caught from the stream Eğlence near the Seyhan Dam in Adana (Füsun Erk’akan, pers. comm., 2021). Erk’akan et al. (2007:81) diagnose O. seyhanicola (as Schistura seyhanicola in the description, as Nanoschistura seyhanicolo in Figure 11 ) by lacking scales, having an incomplete lateral line, a long and pointed snout, and a series of large, midlateral blotches ( Erk’akan et al. 2007). A series of other characters were named but the character states are not given. The caudal fin was already broken and lost in the holotype when it was examined and the colour pattern of the individual had faded; the remaining pattern still seen on the drawing of the type has been lost since.

Both species identified by Geiger et al. (2014) as O. seyhanicola have scales on the flank and therefore, Freyhof & Geiger (2021) suggest, that a third species might be involved. Füsun Erk’akan and Filiz Özdemir (Ankara) made the holotype of O. seyhanicola ( Fig. 6 ) available. While it is clear that this is the individual on the drawing of the holotype published by Erk’akan et al. (2007), the description and the characters seen on the type do not fit together. Obviously, the scales have been overlooked by Erk’akan et al. (2007), as the flank of the type is covered by scales and the lateral line is complete terminating at the anterior part of the hypural complex.

Erk’akan et al. (2007) have drawn six midlateral blotches from behind the tip of the dorsal fin to the caudal peduncle in O. seyhanicola , a situation also found in O. sarus and O. evreni . The holotype of O. seyhanicola is drawn with two black spots at the caudal-fin base, the upper larger than the lower, but the position and size of these spots do not correspond to the situation found in the type, where two remnants of blotches are situated anterior to the end of the hypural complex ( Fig. 7 ). Therefore, these blotches do not correspond to the blotches found at the end of the hypural complex in O. sarus , and in this species, the upper blotch is always much smaller than the lower one. In some individuals of O. seyhanicola there are black spots at the level of the caudal-fin origin, both situated in the short, adipose crest directly in front of the first unbranched caudal-fin rays, while these blotches are clearly situated below and above these crests in the type of O. seyhanicola . Obviously, these blotches in O. seyhanicola belong to the pattern of the caudal peduncle and therefore do not support the identification of the holotype as the species described here as O. sarus . Morphometric characters of O. seyhanicola (FFR 1499, FSJF 4108, Table 3 ) and O. sarus ( Table 2 ) overlap largely and do not allow to confidently identify the holotype of O. seyhanicola ( Table 3 ) to belong to one of the two species discussed here. However, it is much closer to FFR 1499 & FSJF 4108 by having the caudal peduncle depth is 2.0 times in its length (vs. 1.5–1.8 in O. sarus ; 1.4–2.2 in other materials of O. seyhanicola ), a more posterior position of the dorsal- and pelvic fins (pre-dorsal length 56% SL vs. 45–52 in O. sarus , 51–53 in O. seyhanicola ; pre-pelvic length 57% SL vs. 48–53 in O. sarus , 50–55 in O. seyhanicola ), and a greater distance between pectoral- and pelvic-fin origin (32% SL vs. 25–29 in O. sarus , 27–32 in O. seyhanicola ). Therefore, we identify FFR 1499 ( Figs. 8–9 ) and FSJF 4108 as O. seyhanicola . Additional fish from the Ceyhan drainage (FSJF 2959; Fig. 10 ) were also identified as O. seyhanicola based on the character states given above confirming the occurrence of O. seyhanicola in this river also. But more work is definitively needed to understand the distribution of loaches in the area.

One of us (BY) showed pictures of the species identified here as O. seyhanicola and O. sarus to Füsun Erk’akan, and she argued that the fish described here as O. sarus is O. seyhanicola and the one we identify as O. seyhanicola might tentatively be conspecific with O. euphraticus , or a different species (Füsun Erk’akan, pers. comm., 2021). However, Füsun Erk’akan based this identification solely on the presence of lateral blotches on the flank in the type of O. seyhanicola (vs. bars in some of the individuals that we identified here as O. seyhanicola ). We cannot use this statement, as lateral blotches are present in the holotype of O. seyhanicola , and are also found in several of the freshly caught fishes of the species identified here as O. seyhanicola ( Fig. 8 ) as well as in O. sarus ( Fig. 2–5 ). Therefore, the identification of the species cannot be based solely on the presence of lateral blotches vs. bars. The arguments for why we identify FFR 1499, FSJF 4108 as O. seyhanicola are given above.

In the holotype of O. seyhanicola , the caudal peduncle depth is 2.0 times in its length and other individuals examined have 1.4–2.2. This situation is very similar to O. evreni (1.8–2.4), a species not recorded from the Seyhan, but from the adjacent Ceyhan. Indeed, since the caudal fin and the colour pattern are lost in the holotype of O. seyhanicola , we cannot fully exclude that it might be conspecific with O. evreni . Future field-work is needed to test whether O. evreni might occur also in the Seyhan and to compare these populations with the type of O. seyhanicola .

Oxynoemacheilus sarus belongs to the O. persa species group and is most closely related to O. shehabi from the upper Orontes, O. euphraticus from the Euphrates and Tigris, O. karunensis from the Karun and O. persa from Central Iran. The phylogenetic relationships among O. shehabi , O. sarus , O. euphraticus , and between O. persa and O. karunensis are poorly supported in our phylogenetic tree ( Fig. 1 ).

The new species is distinguished from these and other species in the O. persa species group by a combination of characters, none of them unique. It belongs to a group of species ( O. argyrogramma , O. euphraticus , O. hanae , O. karunensis , O. kurdistanicus , O. marunensis , O. persa , and O. shehabi ) in which males have a suborbital groove (vs. absent in O. chomanicus , O. kentritensis , O. zagrosensis , and O. zarzianus ) and a deeply emarginate or forked caudal fin (vs. slightly emarginate or truncate in O. chomanicus , O. kentritensis , O. zagrosensis , and O. zarzianus ).

Oxynoemacheilus sarus is distinguished from O. shehabi by possessing a midlateral series of large blotches, disconnected from the saddles on the back (vs. 5–7 bars, irregularly shaped and set, extending to the middorsal saddles and meeting the contralaterals), and the caudal peduncle is 1.5–1.8 times longer than deep (vs. 1.8–2.4).

The new species is distinguished from O. argyrogramma and O. marunensis by possessing a midlateral series of blotches on the flank without a mottling pattern above and/or below the blotches (vs. marbled or mottled colour pattern on the flank in O. argyrogramma , mottled above and below the midlateral series of blotches in O. marunensis ), no, or only a very short, incision in the upper lip (vs. a deep median incision in O. argyrogramma ), and 9+8 branched caudal-fin rays (vs. 8+7 or 8+ 8 in O. marunensis ). Oxynoemacheilus shehabi is distinguished also from O. euphraticus and O. kurdistanicus by possessing no, or only a very shallow incision in the upper lip (vs. a deep median incision), and a midlateral series of blotches on the flank (vs. flank pattern irregularly mottled or marbled on flank in front of dorsal fin, with bars behind the dorsal-fin base). 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 having two distinct black blotches at the caudal-fin base (vs. usually a chevron shaped bar at the caudal-fin base, dissociated into a large lower blotch and a small spot or into two, usually indistinct spots in few individuals, usually fused to the last midlateral blotch). The new species is distinguished from O. karunensis and O. persa by possessing a well-developed pelvic axillary lobe, fully attached to the body (vs. lobe absent or rudimentary, shallow and knob-shaped); the caudal peduncle is 1.5–1.8 times longer than deep (vs. 1.7–3.1 in O. karunensis ). Oxynoemacheilus sarus has a regular series of midlateral blotches (vs. a midlateral series of short bars or vertically elongated blotches in O. karunensis ), and no or sparse spots, vermiculation or mottling between the blotches on the back and the flank above the lateral midline (vs. many minute dark-brown spots, with a mottled colour pattern between the saddles and large blotches in O. karunensis )

Figures

FIGURE 1. Maximum likelihood estimation of the phylogenetic relationships based on the mitochondrial DNA barcode region (GTR model, discrete Gamma distribution for rate differences with 5 categories (+G, parameter = 0.1612). Initial tree(s) for the heuristic search were obtained by applying the Neighbor-Joining method to a matrix of pairwise distances estimated using the Maximum Composite Likelihood (MCL) approach. Nucleotide positions with less than 98% site coverage were eliminated, resulting in 555 analysed positions each from 56 nucleotide sequences. Numbers of major nodes indicate bootstrap values from 500 pseudo-replicates from the ML and NJ method. The tree is drawn to scale with branch lengths depicting number of substitu- tions per site.

FIGURE 2. Oxynoemacheilus sarus, FFR15585, holotype, 52.5 mm SL; Turkey: lower stream Çakıt.

FIGURE 3. Oxynoemacheilus sarus, paratypes, FFR15522, from the top, 53 mm SL; 51 mm SL: lower stream Çakıt.

FIGURE 4. Oxynoemacheilus sarus, FFR15585, holotype, 52.5 mm SL; Turkey: lower stream Çakıt.

FIGURE 5. Oxynoemacheilus sarus, from the top, FFR 15585, holotype, 52.5 mm SL; FFR 15522, paratype, 51 mm SL; FSJF 2327, paratype 47 mm SL; Turkey: lower stream Çakıt.

FIGURE 6. Oxynoemacheilus seyhanicola, HUIC SEY-1, holotype, 40.3 mm SL; Turkey: Dam bridge near Adana.

FIGURE 7. From the left: Oxynoemacheilus seyhanicola, HUIC SEY-1, holotype, 40.3 mm SL; Turkey: Dam bridge near Adana; Oxynoemacheilus sarus, FSJF 2327, 49.6 mm SL; Turkey: Turkey: lower stream Çakıt; Oxynoemacheilus seyhanicola, FSJF 2959, 45.9 mm SL; Turkey: stream tributary to stream Kirksu. Red rectangle indicates the position of black blotches in HUIC SEY-1. Red ovals indicate black blotches in O. sarus. Black line indicate the posterior end of the hypural complex.

FIGURE 8. Oxynoemacheilus seyhanicola, FFR 1499, from the top, 43 mm SL; 38 mm SL; 35 mm SL; Turkey: stream Üçürge at Karaisali.

FIGURE 9. Oxynoemacheilus seyhanicola, FFR 1499, 53 mm SL; Turkey: stream Üçürge at Karaisali.

FIGURE 10. Oxynoemacheilus seyhanicola, FSJF 2959, from the top: 42 mm SL; 46 mm SL; 43 mm SL; 42 mm SL; Turkey: a tributary of stream Kırksu.

FIGURE 11. Oxynoemacheilus evreni, from the top: FSJF 2897, 50 mm SL; Turkey: stream Sevdili; FSJF 2640, 60 mm SL; Turkey: stream Terbüzek II.