Oxynoemacheilus zarzianus, Freyhof, Jörg & Geiger, Matthias, 2017

Freyhof, Jörg & Geiger, Matthias, 2017, Oxynoemacheilus zarzianus, a new loach from the Lesser Zab River drainage in Iraqi Kurdistan (Teleostei: Nemacheilidae), Zootaxa 4273 (2), pp. 258-270 : 261-268

Oxynoemacheilus zarzianus , new species

( Figs. 3–6 )

Holotype. ZFMK Ich-103667, 67 mm SL; Iraq: stream Kunamasi in Sevanja, 35°47.35'N 45°24.18'E; J. Freyhof, 6 June 2012.

Paratypes. FSJF 3352, 28 , 39–69 mm SL; same data as holotype. — FSJF 3348, 16 , 46–68 mm SL; Iraq: stream in Merga village , 36°03.09'N 45°05.67'E. — FSJF 3651, 18 , 54–75 mm SL: Iraq: stream Kunamasi in Kunamasi, 35°47'48"N 45°24'49"E.

Additional material (non types). FSJF 3372, 30 , 43–71 mm SL; Iraq: stream Suraw near Suraw village, 35°45.76'N 45°59.09'E.

Material for molecular genetic analysis: FSJF DNA- 2236 ; Iraq: stream Kunamasi in Sevanja, 35°47.35'N 45°24.18'E ; GenBank accession KY849797 .— FSJF DNA- 2203 ; Iraq: stream in Merga village , 36°03.09'N 45°05.67'E ; GenBank accessions KY849792 , KY849793 , KY849794 .— FSJF DNA- 2225 ; Iraq: stream Suraw near Suraw village, 35°45.76'N 45°59.09'E ; GenBank accessions KY849795 , KY849796 , KY884997 .

Diagnosis. Oxynoemacheilus zarzianus is distinguished from the other species of Oxynoemacheilus in the Tigris drainage by a combination of characters, none of them unique. Oxynoemacheilus zarzianus belongs to a group of species ( O. chomanicus , O. frenatus , O. gyndes , O. hazarensis , O. kentritesensis , O. kiabii , O. zagrosensis ), which lack a suborbital groove in males (vs. present in O. bergianus , O. euphraticus , O. hanae , O. longipinnis , O. karunensis , O. kurdistanicus and O. parvinae ) and have a slightly emarginate or truncate caudal fin (vs. deeply emarginate or forked in O. bergianus , O. euphraticus , O. hanae , O. longipinnis , O. karunensis , O. kurdistanicus and O. parvinae ).

Oxynoemacheilus zarzianus is most similar to O. chomanicus ( Fig. 2 ), which also occurs in the Lesser Zab drainage. It is distinguished from that species by having a convex, very rarely straight dorsal profile (vs. straight), a wider interorbital distance (1.1–1.4 times in snout length vs. 1.4–1.5) and a deeper caudal peduncle (caudalpeduncle depth 1.0–1.2 times in caudal-peduncle length vs. 1.3–1.4). It is distinguished from O. zagrosensis , an additional species from the Lesser Zab drainage, by having th e posterior process of the bony air-bladder capsule directed posteriorly (vs. directed laterally). The new species is distinguished from O. kentritesensis , from the Botan River in the Turkish Tigris drainage, by having a short maxillary barbel, which is often rudimentary, reaching the vertical of the anterior eye margin or the vertical of the middle of the eye in some individuals (vs. reaching beyond middle of the eye; maxillary barbel 12–26% HL vs. 27–34), a wider interorbital distance (31–40% HL vs. 27–32; 1.1–1.4 times in snout length vs. 1.5–1.8) and always 8+8 branched caudal-fin rays (vs. 10+9–9+8). Furthermore, the colour pattern on the flank behind the dorsal-fin base is usually mottled or marmorate in O. zarzianus . The marmorate pattern is usually organised in vertically elongated blotches. In O. kentritesensis , there are distinct, but irregularly shaped and set bars on the flank behind the dorsal-fin base.

Oxynoemacheilus zarzianus is superficially similar to O. frenatus from the upper Tigris drainage by having the colour pattern on the flank often interrupted by an unpigmented zone along the anterior part of the lateral line (vs. not interrupted on anterior part of flank in other similar species). It is distinguished from O. frenatus by having a complete lateral line (vs. incomplete) and a median incision in the upper lip (vs. absent or with shallow groove in the middle of the upper lip). It is distinguished from O. hazarensis , O. gyndes and O. kiabii by having scales on the back and flank in front of the anus (vs. absent) and a complete lateral line (vs. incomplete). The new species is further distinguished from O. kiabii by the presence of a central pore in the supratemporal canal (vs. absence), three pores in the supratemporal canal (vs. 4–6 pores) and a shorter head (length 22–25% SL vs. 24–30). Oxynoemacheilus zarzianus is further distinguished from O. hazarensis by having a deeper caudal peduncle (caudal peduncle 1.0–1.2 times longer than deep vs. 1.6–1.9).

Description. For general appearance see Figs. 3–6 ; morphometric data are provided in Table 2. Medium sized and stout species with a blunt head. Dorsal profile convex, rarely straight between head and dorsal-fin origin. Body deepest at dorsal-fin origin or at about midline between nape and dorsal-fin origin, depth decreasing at dorsal-fin base and then remains almost equal towards caudal-fin base. A prominent hump before dorsal-fin origin in some individuals. Greatest body width at pectoral-fin base. Section of head roundish, flattened on ventral surface. Interorbital distance wide, 1.1–1.4 times in snout length. Caudal peduncle compressed laterally, 1.0–1.2 (mean 1.1) times longer than deep. Axillary lobe at base of pelvic fin absent or a very shallow pad. Pelvic-fin origin below second or third branched dorsal-fin ray. Anal-fin origin behind middle between base of last dorsal-fin ray and caudal-fin origins. Pectoral fin reaching approximately 50–60% of distance from pectoral-fin origin to pelvic-fin origin. Pelvic fin not reaching vertical of dorsal-fin tip, not reaching to anus. Anus about 0.9–1.3 eye diameter in front of anal-fin origin. Anal fin not reaching caudal-fin base. High to shallow dorsal and shallow ventral adipose crest on caudal peduncle. Dorsal crest reaching to vertical of anal-fin base. Margin of dorsal fin convex. Caudal fin slightly emarginate. Largest known specimen 75 mm SL.

Dorsal fin with 8½ (n=15) branched rays. Anal fin with 5½ branched rays. Caudal fin with 8+8 (n=15) branched rays. Pectoral fin with 10–12 and pelvic fin with 6–8 rays. Body covered by scales except anterior part of back, scales isolated and embedded in skin on flank before dorsal-fin origin. Lateral line complete. One lateral pore and 1 central pore in supratemporal canal. In one out of 20 individuals examined for this character, there are two central pores in supratemporal canal. Anterior nostril opening at end of a low, pointed and flap-like tube. Posterior tip of anterior nostril overlapping posterior nostril when folded backwards. No suborbital groove in males. Mouth small, arched ( Fig. 7 ). Lips thick, with marked furrows. A deep median interruption in lower lip. A median incision in upper lip. Processus dentiformis narrow and pointed. No median notch in lower jaw. Barbels short, inner rostral barbel reaching to base of maxillary barbel or to a point between base of outer rostral and maxillary barbel; outer one reaching to base of maxillary barbel. Maxillary barbel very short, rudimentary in some individuals, reaching vertical of anterior margin or middle of eye in others. No suborbital groove or flap in males.

Coloration. Body yellowish in life and preserved individuals. Head with very fine and dense brown mottling on top, on cheeks and lateral side of head, without colour pattern ventrally. No pigmentation below a line from pectoral-fin base to anus. Back brown or pale-brown with 3–4 fuzzy, irregularly shaped and set dark-brown blotches, marmorate of mottles in some individuals. Colour pattern on flank not interrupted or with a narrow interruption along anterior part of lateral line. A large, irregularly shaped, dark-brown blotch at dorsal-fin-origin and below posterior half or dorsal-fin base. Flank mottled, behind dorsal-fin origin marmorate or with 3–10 darkbrown, irregularly shaped and set, horizontally elongated blotches, about as wide as or narrower than interspaces in many individuals. Upper part of caudal peduncle often with 3–5 irregularly shaped blotches, some blotches fused with midlateral blotches in some individuals. A wide, dark-brown, irregularly shaped bar at caudal-fin base or two large dark-brown blotches at upper and lowermost caudal-fin base. Last unbranched dorsal-fin ray with a black spot at base of ray. Dorsal-fin with many elongated, dark-brown blotches on rays, forming two bands in some individuals, fuzzy in some others. Caudal-fins with many elongated, dark-brown blotches on rays, forming 2–3 wide, irregularly shaped, dark-brown bands in most individuals, fuzzy in some others. Anal-, pelvic- and pectoral fins with many elongated blotches on rays.

Distribution. Oxynoemacheilus zarzianus was found at three places in the Lesser Zab drainage. One spring fed stream ( Fig. 8 ) in the Qal-ah Chulan River drainage, one headwater stream in the Qal-ah Chulan River drainage and in one spring east of the Dukan reservoir. The Qal-ah Chulan is a tributary of the Lesser Zab River, entering the Lesser Zab from the south at about Hawat in Iraq and the Dukan reservoir is a dam lake of the Lesser Zab River.

Etymology. Oxynoemacheilus zarzianus is named for the Zarzian culture, which is an archaeological culture of late Paleolithic and Mesolithic in Kurdistan. An adjective.

Remarks. The fishes from the stream Suraw (FSJF 3372) a headwater stream in the Qal-ah Chulan River drainage are distinguished from the two other populations by at least 2.6% K2P distance based on the cytochrome b sequences. However, these fishes fit perfectly the diagnosis of O. zarzianus and no morphological difference was found. Therefore, they are identified as O. zarzianus .

Four species of Oxynoemacheilus are actually known from the Lesser Zab River drainage. Oxynoemacheilus kurdistanicus is widespread. This is a slender species with a deeply emarginate caudal fin and very narrow caudal peduncle. The occurrence of three ( O. chomanicus , O. zarzianus , O. zagrosensis ) superficially similar, deep bodied species with a slightly emarginate caudal fin and a very similar colour pattern in the Lesser Zab drainage is the surprising result of this study. The fishes from the Suraw represent even an additional, remarkably isolated population of O. zarzianus . There is indication, that these deep bodied loaches are specialists to headwater streams. In the upper Choman River at the Iraq-Iran border area, JF was not able to find O. chomanicus in the Choman River itself, but only in a very small tributary stream. All over the Lesser Zab drainage in Iraq, usually only O. kurdistanicus is present, but at most sites, no Oxynoemacheilus could be found at all. We suspect that the deep bodied Oxynoemacheilus in the Lesser Zab drainage all have very limited distribution areas, being restricted to springs, cold, spring fed streams or high altitude streams. This very specific habitat choice seems to lead to highly isolated populations and our molecular data support the view that even within one tributary of the Lesser Zab (Qalah Chulan River), isolated populations occur (Suraw & Kunamasi). Our molecular data also support the view that this isolation is not of recent origin but must have lasted for substantial period of time. While deep bodied Oxynoemacheilus species are well known for local endemics, the diversity in the Lesser Zab drainage is an exceptional case.

The occurrence of 15 different species of Oxynoemacheilus within the Tigris drainage is a surprising situation. If we consider that seven additional species occur in the Euphrates drainage, including Lake Van basin ( O. araxensis , O. argyrogramma , O. ercisianus , O. erdali , O. kaynaki , O. paucilepis , O. samanticus ) this raises the number of Oxynoemacheilus species within this combined drainage system to twenty-two. We are not aware of any other genus of fishes with so many species within one drainage system in the Western Palaearctic and we are not aware of any other river being inhabited by so many different Oxynoemacheilus species. In the old world, similar or even much higher species numbers of one genus within one drainage system are found in the Indus, Ganges, Mekong and some other major rivers in South and South-East Asia ( Freyhof & Serov 2001, Kottelat 1990, Kottelat 2000, Kottelat 2012). Here also, Nemacheilid loaches are known to be very diverse and restricted to one or few headwater streams within these large drainage systems. Like no other group of freshwater fishes, Nemacheilid loaches seem to become easily isolated in headwaters of rivers.

Comparative material. Listed by Freyhof et al. (2012), Freyhof (2016), Freyhof & Abdullah (2017), Freyhof & Özuluğ (2017) and Freyhof et al. (2017).

Figures

FIGURE 2. Oxynoemacheilus chomanicus, FSJF 3644, 62 mm SL; Iraq: Choman River at Alut.

FIGURE 3. Oxynoemacheilus zarzianus, ZFMK Ich- 103667, holotype, 67 mm SL; Iraq: stream Kunamasi.

FIGURE 4. Oxynoemacheilus zarzianus, FSJF 3352, paratypes, 62 mm SL, 54 mm SL, 50 mm SL; 39 mm SL; Iraq: stream Kunamasi.

FIGURE 5. Oxynoemacheilus zarzianus, FSJF 3352, paratypes, 62 mm SL, 54 mm SL, 50 mm SL; 39 mm SL; Iraq: stream Kunamasi.

FIGURE 6. Oxynoemacheilus zarzianus, from the top, FSJF 3352, paratype, male, 62 mm SL, stream Kunamasi; FSJF 3651, paratype, male, 73 mm SL; 60 mm SL; Iraq: stream Kunamasi; FSJF 3348, paratype, male, 60 mm SL; Iraq: stream in Merga; FSJF 3372, 55 mm SL, female; Iraq: stream Suraw.

FIGURE 7. Oxynoemacheilus zarzianus, ZFMK Ich- 103667, holotype, 67 mm SL; Iraq: stream Kunamasi.

FIGURE 8. Type locality of O. zarzianus; Iraq: stream Kunamasi.