Oxynoemacheilus shehabi, Freyhof & Geiger, 2021

Freyhof, Jörg & Geiger, Matthias F., 2021, Oxynoemacheilus shehabi, a new nemacheilid loach from the upper Orontes in southern Syria (Teleostei: Nemacheilidae), Zootaxa 4908 (4), pp. 571-583 : 573-581

Oxynoemacheilus shehabi , new species

( Figs 2–6 )

Holotype. ZFMK ICH 124181 , 46.3 mm SL; Syria: Orontes at Al Qusayr , 34.5086 36.5389.

Paratypes. ZFMK ICH-125126-28 , 3 , 41.5–47.6 mm SL; same data as holotype .

Material used in molecular genetic analysis. FSJF DNA-1227 ; same data as holotype (GenBank accession numbers: KJ553795 , KJ554073 )

Diagnosis. Oxynoemacheilus shehabi is distinguished from O. hamwii and O. namiri , the two other species of Oxynoemacheilus known from the Orontes , by possessing a very slender caudal peduncle (caudal-peduncle depth 1.8–2.4 times in its length vs. 1.2–1.4 in O. namiri ; 1.4–1.9 in O. hamwii ), a suborbital groove in male (vs. absent in O. namiri ), and a complete lateral line terminating on the caudal-fin base (vs. incomplete, terminating behind the dorsal-fin base, or on the caudal-fin base in some individuals in O. namiri ). It is further distinguished from O. hamwii by possessing two, usually indistinct, black blotches or spots at the caudal-fin base (vs. one bold central blotch or no bold black blotch on the caudal-fin base, often an irregularly-shaped black bar at the caudal-fin base), and the flank with 5–7 irregularly shaped bars (vs. flank in juveniles with a midlateral series of horizontally elongate blotches, adults with a brown marbled pattern). See below to distinguish O. shehabi from other species of the O. persa species group.

Description. See Figures 2–6 for general appearance and Table 2 for morphometric data. Small-sized and slender species. Body deepest at about midline between nape and dorsal-fin origin. Body width greatest at pectoral-fin base. Section of head roundish, flattened on ventral surface, slightly convex in interorbital space, convex on snout. Snout pointed. Caudal peduncle compressed laterally, 1.8–2.4 times longer than deep. Pelvic axillary lobe present, its tip attached to flank. Pelvic-fin origin below first or second branched dorsal-fin ray. Anal-fin origin at about vertical of midline between dorsal and caudal-fin origins. Pectoral fin reaching to approximately 70–90% of distance from pectoral-fin origin to pelvic-fin origin. 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 48 mm SL, expected to grow larger.

Dorsal fin with 8½ branched rays, outer margin concave. Anal fin with 5½ branched rays, outer margin straight or slightly concave. Pectoral fin with 9 branched rays, outer margin straight. Pelvic fin with 7 branched rays, outer margin straight or slightly convex. Caudal fin deeply emarginate with 9+8 branched rays. Flank and back covered by cycloid scales, scales irregularly set on back. Lateral line complete, terminating at caudal-fin 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 lateral pore on each side of supratemporal head canal, 3–4 + 8–10 pores in infraorbital canal, 6–7 pores in supraorbital canal, and 9–10 pores in mandibular canal. 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 one individual, absent in others. Processus dentiformis narrow and rounded. Lower jaw rounded, without median notch. Barbels long; inner rostral barbel reaching base of maxillary barbel, outer reaching to or slightly beyond anterior margin of eye. Maxillary barbel reaching beyond vertical through posterior margin of eye, almost to 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, absent in life. Dorsal head and upper part of cheek brown, without pattern. Ventral surface of head yellowish without pattern. Flank with 5–7 dark-brown bars, thinner than interspaces. Flank bars irregularly shaped and set, extending to middorsal saddles and meeting contralaterals. Shape of flank bars usually interrupted in shape and size at lateral midline, dissociated in blotches on predorsal part of flank in two individuals. Back with 1–2 predorsal saddles, one saddle at dorsal-fin origin and one at posterior dorsal-fin base, and 2–3 saddles behind dorsal fin, all saddles thinner than interspaces. Flank above lateral midline with short, very narrow, brown lines, often oriented along myosepts. One dark-brown blotch at lower caudal-fin base, a second, much smaller blotch at uppermost caudal-fin base, both indistinct in preserved individuals. Posteriormost upper and lowermost caudal peduncle with a pale 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 3–7 bands. Pectoral, anal and pelvic fins with dark-brown blotches on rays; anal fin hyaline or with few blotches.

Distribution. Oxynoemacheilus shehabi was collected from the upper Orontes in Syria. As the species has not been found in the lower Orontes in Turkey, it is expected to be endemic to the southern headwaters of this river.

Etymology. The species is named for Adwan Shehab, one of Syria’s most active and renowned zoologists, who hosted and logistically enabled our team during our field-work in Syria in 2008, when the type material of the species was collected. On 16 th of February 2015, Adwan was killed in the streets of Dara’a as a result of the still ongoing bloody conflict in Syria ( Amr 2015). A noun in genitive.

Remarks. Oxynoemacheilus shehabi is distinguished from other species of Oxynoemacheilus 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. “ seyhanicola ”) 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 ).

The new species is related to a fish identified as O. seyhanicola from the lower Seyhan. This species was described based on a single individual diagnosed by lacking scales, having a long and pointed snout and a series of large, midlateral blotches ( Erk’akan et al. 2007). Geiger et al. (2014) published sequences of two groups of fishes identified as O. seyhanicola , which were very different to each other, both also shown in Fig. 1 . Both populations have scales on the flank but we would need to re-examine the type of O. seyhanicola to verify that there are really no scales. Obviously two species are involved in O. seyhanicola . One of these is related to O. shehabi , while the other is related to O. evreni from the Ceyhan and O. hamwii from the Orontes . We distinguish O. shehabi from those O. “ seyhanicola ” ( Fig. 7 ) being closely related to O. shehabi and not from those related to O. evreni and O. hamwii . Further research is needed to resolve the identity of O. seyhanicola and we cannot fully exclude that a third species might be involved.

Oxynoemacheilus shehabi is distinguished from O. persa and O. “ seyhanicola ” by possessing 5–7 bars, irregularly shaped and set, extending to the middorsal saddles and meeting the contralaterals (vs. flank with a midlateral series of large blotches, disconnected from saddles on the back in O. “ seyhanicola ” and most individuals of O. persa ; blotches sometimes vertically elongated in O. persa , some individuals with 3–5 bars on flank behind the dorsal-fin base), two, usually indistinct, black blotches or spots at caudal-fin base (vs. two very large blotches, usually fused to an irregularly shaped bar in O. persa ); a well-developed pelvic axillary lobe fully attached to the body (vs. no lobe or lobe rudimentary in O. persa ); caudal peduncle 1.8–2.4 times longer than deep (vs. 1.5–1.8 in O. “ seyhanicola ”).

The new species is distinguished from O. argyrogramma and O. marunensis by possessing 5–7 irregularly shaped bars on the flank, dissociated into large blotches on the anterior flank in a few individuals (vs. marbled or mottled colour pattern on flank in O. argyrogramma , mottled with a midlateral series of blotches in O. marunensis ). Further, the caudal peduncle is more slender in O. shehabi (caudal peduncle depth 1.8–2.4 times longer than deep vs. 1.5–1.8 in O. argyrogramma , 1.4–1.9 in O. marunensis ). The two black blotches or spots on the caudal-fin base are small and indistinct in O. shehabi (vs. prominent in life and preserved fishes in O. argyrogramma and O. marunensis ) and it has no, or only a very short, incision in the upper lip (vs. a deep median incision in O. argyrogramma ).

Oxynoemacheilus shehabi is distinguished also from O. euphraticus and O. kurdistanicus by possessing two, usually indistinct, black blotches or spots at the caudal-fin base (vs. very prominent in live and preserved fishes), no, or only a very shallow incision in the upper lip (vs. a deep median incision), and possessing 5–7 irregularly shaped bars on flank (vs. flank pattern irregularly mottled or marbled on flank in front of dorsal fin and with more than 7 bars on the flank behind the dorsal-fin base in O. euphraticus ). Oxynoemacheilus shehabi is further distinguished from O. kurdistanicus by having a more slender caudal peduncle (caudal-peduncle depth 8–9% SL vs. 9–11).

It is distinguished from O. hanae by possessing 5–7 irregularly shaped bars on the flank (vs. a midlateral series of dark-brown roundish or ovoid blotches), confluent with saddles on the back (vs. blotches on the flank not confluent with saddles on the back); mid-lateral blotches reaching down to the ventral side of the caudal peduncle (vs. not reaching), and caudal peduncle 1.8–2.4 times longer than deep (vs. 1.4–1.8).

The new species is distinguished from O. karunensis by possessing a well-developed pelvic axillary lobe, fully attached to the body (vs. lobe absent or rudimentary, shallow and knob-shaped); 5–7 bars on flank (vs. a series of dark-brown roundish or ovoid blotches along mid-lateral flank), bars reaching down to ventral side of caudal peduncle (vs. not reaching), and flank bars confluent with saddles on back (vs. mid-lateral blotches usually not confluent with saddles on back, but often overlapping).

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 = 0.3468). Nucleotide positions with less than 98% site coverage were eliminated, resulting in 591 analysed positions. Numbers of major nodes indicate bootstrap values from 1000 pseudoreplicates from the ML, NJ and MP method. The tree is drawn to scale with branch lengths depicting number of substitutions per site.

FIGURE 2. Oxynoemacheilus shehabi, ZFMK ICH 124181, holotype, 46.3 mm SL; Syria: upper Orontes.

FIGURE 3. Oxynoemacheilus shehabi, ZFMK ICH 124181, holotype, 46.3 mm SL; Syria: upper Orontes (right side reversed).

FIGURE 4. Oxynoemacheilus shehabi, FSJF 2739, paratypes, from top: 41.5 mm SL, 44.7 mm SL, 47.6 mm SL; Syria: upper Orontes.

FIGURE 5. Oxynoemacheilus shehabi, FSJF 2739, paratypes, from top: 41.5 mm SL, 44.7 mm SL, 47.6 mm SL; Syria: upper Orontes.

FIGURE 6. Oxynoemacheilus shehabi; FSJF 2739, paratypes, from top: 41.5 mm SL, 44.7 mm SL, 47.6 mm SL; Syria: upper Orontes.

FIGURE 7. Oxynoemacheilus “seyhanicola”; FSJF 2327, 47 mm SL; Turkey: lower stream Çatkıt.