Oxynoemacheilus isauricus, Yoğurtçuoğlu & Kaya & Özuluğ & Freyhof, 2021

Yoğurtçuoğlu, Baran, Kaya, Cüneyt, Özuluğ, Müfit & Freyhof, Jörg, 2021, Oxynoemacheilus isauricus, a new nemacheilid loach from Central Anatolia (Teleostei: Nemacheilidae), Zootaxa 4975 (2), pp. 369-378 : 372-376

Oxynoemacheilus isauricus , new species

( Figs. 2–4 )

Holotype. IUSHM 2021-1425 , 63 mm SL; Turkey: Isparta prov.: stream Çeltek at Çeltek, south of Şarkikaraağaç , 38.0124N 31.3152E.

Paratypes. IUSHM 2021-1463 , 3 , 48–53 mm SL; FSJF 2523, 5 , 42–50 mm SL; same data as holotype .

Additional material. FFR 01534, 9, 46– 56 mm SL; Turkey: Konya prov.: stream Akçay at Gökçehüyük, 3 km west of Seydişehir , 37.4396N 31.8000E .

Diagnosis. Oxynoemacheilus isauricus is distinguished from all other species of the O. angorae group by having a very slender caudal peduncle (caudal peduncle depth 2.2–2.6 times in its length vs. 1.3–1.6 in O. anatolicus and O. theophilii , 1.5–1.8 in O. angorae , 1.5–1.9 in O. atili , 1.2–1.7 in O. eregliensis , 1.2–1.5 in O. mediterraneus , 1.4–1.8 in O. cinicus , O. germencicus and O. mesudae , and 1.5–2.1 in O. nasreddini ). The new species is further distinguished by a combination of characters not unique to O. isauricus . It occurs sympatric with O. atili ( Fig. 5 ) in Lake Beyşehir basin. Oxynoemacheilus isauricus is further distinguished from this species by having a deeply emarginate caudal fin in which the shortest middle caudal-fin ray is 71–85% of the longest ray of the upper caudalfin lobe (vs. 83–91), a more anterior positioned anal fin (preanal length 68–74% SL vs. 74–77) and a shorter head (head length 21–24% SL vs. 24–26).

The new species is distinguished from O. eregliensis from the wider Lake Tuz basin, O. anatolicus from Lake Burdur basin and the Dalaman drainage, O. angorae from the Sakarya and Kızılırmak drainages and Lake Ilgın basin, and O. mediterraneus from the Aksu and Köprü drainages by possessing a deeply emarginate caudal fin in which the shortest middle caudal-fin ray is 71–85% of the longest ray of the upper caudal-fin lobe (vs. almost truncate, 88–98 in O. eregliensis ; 84–93 in O. anatolicus and 88–92 in O. angorae and forked, 65–76 in O. mediterraneus ). Oxynoemacheilus isauricus is further distinguished from O. eregliensis and O. anatolicus by having a shorter head (head length 21–24% SL vs. 24–27 in both of the species). It is further differentiated from O. mediterraneus by the strongly decreasing body depth between the dorsal- and caudal-fin bases (vs. almost uniform), and the flank blotches being usually disconnected from the saddles on the back (vs. usually connected). It is further distinguished from O. angorae by having irregularly shaped and set, vertically elongated blotches on the flank, rarely a mottled or marbled pattern (vs. series of dark-brown midlateral blotches usually fused into a wide, irregular shaped midlateral stripe, rarely a mottled pattern). It is further distinguished from O. anatolicus by the upper part of the cheek with none or few vermiculated dark brown spots (vs. mottled).

The new species is further distinguished from O. nasreddini from the Lake Ilgýn, Eðirdir, Eber and Akşehir basins, by a more anteriorly positioned pelvic-fin (prepelvic length 48–51% SL vs. 51–55), and a series of midlateral blotches on flank (vs. usually a series of short bars on caudal peduncle).

Oxynoemacheilus isauricus is further distinguished from O. germencicus , O. mesudae and O. cinicus from the Büyük Menderes drainages, by the tip of the anal fin not reaching the ventral adipose crest, if present (vs. usually reaching to or slightly beyond the adipose crest), and a faint inner axial stripe (vs. absent).

It is further distinguished from O. theophilii , from the Bakır drainage ( Turkey) and Lesbos Island ( Greece) by a strongly decreasing body depth between the dorsal- and caudal-fin bases (vs. body depth almost uniform), and irregularly shaped and set, usually roundish, rarely vertically elongated, blotches (vs. mottled without blotches).

Description. See Figures 2–4 for general appearance and Table 2 for morphometric data. Medium-sized, slender species. Head short, body depth at dorsal-fin origin 1.1–1.3 times in head length. Body deepest and widest at about midline between nape and dorsal-fin origin. Body depth strongly decreasing between anterior dorsal-fin base, until caudal-fin bases. Section of head roundish, flattened on ventral surface, slightly convex in interorbital space, convex on snout. Snout roundish. Caudal peduncle compressed laterally, 2.2–2.6 times longer than deep. No or only a rudimentary pelvic axillary lobe at base of pelvic fin, fully attached to flank. Pelvic-fin origin below second or third 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 60–70% of distance from pectoral-fin origin to pelvic-fin origin in female and 80–100% in male. Pelvic fin usually reaching to genital papillae, rarely reaching anus; reaching vertical tip of last dorsal-fin ray or slightly anterior to that point. Anus about 60–110% of an eye diameter anterior to anal-fin origin. Anal fin not reaching caudal-fin base. An elevated, short dorsal and ventral adipose crest on caudal peduncle behind vertical of posterior anal-fin base in some individuals, shallow or absent in other individuals. Largest known individual 63 mm SL.

Dorsal fin with 7½ branched rays, outer margin slightly concave. Anal fin with 5½ branched rays, outer margin straight or slightly concave. Pectoral fin with 8–9 branched rays, outer margin straight. Pelvic fin with 6 branched rays, outer margin straight or slightly convex. Caudal fin deeply emarginate, shortest middle caudal-fin ray 73–85% of the longest ray of upper caudal-fin lobe. Caudal fin with 9+8 (9), 9+9 (1) or 8+8 (1), branched rays. Flank and back covered by scales, scales irregularly set on predorsal back, densely set on predorsal flank below lateral line. Chest and belly without scales. Head and flank covered nuptial tubercles in males. Tubercles densely set on head and in suborbital flap ( Fig. 6 ) and pre-dorsal flank and rare on post-dorsal flank above lateral line. Lateral line complete, terminating on hypural complex. Anterior nostril opening at end of a low, ovoid, flap-like tube. Posterior tip of anterior nostril overlapping posterior nostril when folded backward. One central pore, one lateral pore on each side of supratemporal head canal, two pores in temporal head canal, 9–11 pores in infraorbital canal, 6–8 pores in supraorbital canal, and 8–10 pores in preoperculo-mandibular canal. A suborbital flap in male. Mouth small, arched. Lips thick without furrows, lower lip thicker than the upper lip. A deep median interruption in lower lip. Upper lip with a small and shallow median incision ( Fig. 6 ). Processus dentiformis narrow and rounded. Lower jaw rounded, without median notch. Barbels short; inner rostral barbel usually not reaching base of maxillary barbel, outer reaching to vertical of posterior nare, not reaching to anterior eye margin. Maxillary barbel reaching to or slightly exceeding pupil, not exceeding through posterior eye-margin.

Coloration. Background colour yellow or pale-brown with dark-brown pattern in live and preserved individuals. Dorsal head and upper part of cheek with a vermiculate or marbled pattern, cheek without pattern in a few individuals. Ventral surface of head yellowish without pattern. Flank marbled in few individuals, usually with 8–11 roundish or vertically elongate, irregularly set and shaped blotches along lateral midline, narrower or as wide as interspaces. Shape of blotches often interrupted along lateral line. Blotches on flank loosely connected by a faint inner axial stripe in preserved individuals. Inner-axial stripe absent in life. Few blotches connected to middorsal saddles, usually disconnected. Midlateral blotches usually dissociated into a fine marbles or mottled pattern on predorsal part of flank, less dissociated on postdorsal part. Back with 2–3 irregularly set and shaped predorsal saddles, saddles usually dissociated into a mottled or vermiculated pattern, 3–5 irregularly set and shaped saddles behind dorsal-fin base. Several spots, vermiculation or a mottled pattern between blotches on back and flank above lateral midline. An irregularly shaped dark-brown bar or two dark-brown blotches, often connected to each other at caudal-fin base. Dorsal fin with many, small brown blotches on rays, forming 2–3 indistinct bands. Caudal fin with many small brown blotches on rays, usually forming 2–3 distinct narrow bands. All fins yellowish to pale grey. Anal and pelvic fins hyaline in life, yellowish in preserved individuals, without blotches on rays in most individuals.

Distribution. Oxynoemacheilus isauricus was found in tributaries of Lakes Beyşehir and Suğla in Central Anatolia.

Etymology. The species is named after the ancient name for Isauria, a region in Central Anatolia. An adjective.

Remarks. The species of the O. angorae group are the only Oxynoemacheilus found in the Turkish Aegean basin, the tributaries of the Bay of Antalya and in Central Anatolian endorheic basins. Only O. ciceki from the Sultan marshes in the eastern part of Central Anatolia belongs to the O. hamwii group (see Geiger et al. 2014). Oxynoemacheilus isauricus is distinguished from O. ciceki by having 8–11 roundish or vertically elongate, irregularly set and shaped midlateral blotches along the flank (vs. flank with many small rounded spots or mottled), the back with 2–3 irregularly set and shaped predorsal saddles, dissociated in some individuals into a mottled or vermiculated pattern (vs. back with 3–6 irregularly set and shaped predorsal saddles, saddles dissociated into 3–4 paired and rounded blotches in some individuals). Oxynoemacheilus atili is very widespread in the Lake Beyşehir and Suğla basins and is known also from the Manavgat River, which drains water from Suğla Lake to the Mediterranean. We found O. isauricus and O. atili syntopic in the stream Çeltek but would expect that both species usually occur together. Further field-based research is needed to gain a better understanding of the distribution ranges of O. isauricus , which was only found at two quite distant places.

Figures

FIGURE 2. Oxynoemacheilus isauricus, IUSHM 2021-1425, holotype, male, 63 mm SL; Turkey: stream Çeltek.

FIGURE 3. Oxynoemacheilus isauricus, from top: paratype, IUSHM 2021-1463, male, 53 mm SL; Turkey: stream Çeltek; ad- ditional material FFR 01534, male, 53 mm SL; female, 48 mm SL; Turkey; stream Akçay.

FIGURE 4. Oxynoemacheilus isauricus, not preserved, about 50 mm SL; Turkey: stream Çeltek.

FIGURE 5. Oxynoemacheilus atili, from top: FFR 15525, 61 mm SL; FFR 15611, 51 mm SL; Turkey: stream Eylikler; FFR 15612, 55 mm SL; Turkey: Aslandoğmuş; FSJF 2267, 68 mm SL; Turkey: Eflatunpınarı.

FIGURE 6. Oxynoemacheilus isauricus, IUSHM 2021-1425, holotype, male, 63 mm SL; Turkey: stream Çeltek. Ventral (left) and lateral (right) of head.