Petroleuciscus esfahani Coad & Bogutskaya, 2010, new species
Creators: name: Coad, Brian W.
name: Bogutskaya, Nina G.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Cypriniformes
Cyprinidae
Petroleuciscus
Petroleuciscus esfahani

description: Petroleuciscus esfahani, new species
(Fig. 1, 2, 3 a)
Holotype (Fig. 1): CMNFI 1979-0249, female, 106.7 mm SL, IRAN: Esfahan, stream at Dizaj in the southern Zayandeh River basin, 31°55’N, 51°30’E, B. W. Coad and Sh. Mansoorabadi, 9 June 1977.
Paratypes. CMNFI 1979-0251, 134, 22.1–83.7 mm SL, Iran, Esfahan, stream 1 km east of Daran, Pelasegan River tributary in the northern Zayandeh River basin, 32°59’N, 50°26’E, B. W. Coad and Sh. Mansoorabadi, 10 June 1977.
Diagnosis. The species is distinguished by a combination of characters from other members of the genus, including a mode of 8½ dorsal-fin branched rays, modally 10–11½ anal-fin branched rays, small scales on the flank numbering 44–54 pored scales to the hypural fold while total lateral-line scales number 45–56, a pharyngeal-tooth formula commonly 2.5–4.2, and total vertebrae commonly 40–42, the abdominal + caudal vertebral formulae being usually 22+19, 22+20 and 21+20.
Description. Holotype. Dorsal-fin with 3 unbranched and 8½ branched rays, anal fin with 3 unbranched and 10½ branched rays, pectoral fin with 14 branched rays, and pelvic fin with 8 branched rays. Scales in lateral line to hypural fold 45, total lateral-line scales 47, scales around caudal peduncle 15, predorsal scales 23, scales between lateral line and dorsal-fin origin 9, scales between lateral line and anal-fin origin 6, and scales between lateral line and pelvic-fin origin 5. Total gill rakers in outer row of first gill arch 13, d total vertebrae 41: 22 abdominal (including 14 predorsal vertebrae) and 19 caudal (Fig. 3 a).
The body is rounded in cross section with the upper body profile almost straight and the lower body profile gently convex. The snout is triangular and pointed. The lower jaw projects slightly compared to the upper jaw, forming a distinct chin such that the mouth is slightly superior. The tip of the mouth cleft is on a level with the upper margin of the pupil. The mouth cleft extends back to a level with the rear of the nostrils, and the lower jaw-quadrate junction is at the vertical through the anterior margin of the eye (Fig. 3 a). The anal-fin origin is behind the dorsal-fin insertion. The dorsal-fin is truncate and the anal-fin margin is rounded anteriorly, becoming truncate posteriorly. The caudal fin has a shallow fork with the lobes rounded.
The lateral line is moderately decurved and is centrally located on the caudal peduncle. There is a pelvic axillary scale. Scales below the dorsal-fin have a subcentral anterior focus, numerous fine circuli, relatively few anterior and posterior radii with no radii in the lateral fields, a rounded posterior margin and a wavy anterior margin. Gill rakers are moderately elongate and extend to the second adjacent raker when appressed.
General topography of cephalic sensory canals and numbers of pores are typical of most Petroleuciscus, as described by Bogutskaya (1995, 1996, 2002). The supraorbital canal is short and terminates at the parietalfrontal border (thus not entering the parietal), and has 9 pores, with 3 and 7 canal openings on the nasal and frontal bones, respectively. The infraorbital canal has 18 (left side) and 16 (right side) pores with 5 (left side) and 4 (right side) canal openings on the first infraorbital. The preopercular-mandibular canal is complete, with 17 (left side) and 16 (right side) pores with 3 (left side) and 2 canal openings on the dentary, 10 on the preoperculum and 2 on the operculum. The supratemporal canal is incomplete (mesially interrupted), with 3+3 pores.
There is no distinctive colour pattern in preserved fish. The flank above the lateral line bears a fine dark speckling of melanophores and is mostly unpigmented below the lateral line. Melanophores are present on the upper part of the operculum and extend down along the posterior edge. Melanophores on the cheek ring the lower orbit. The back bears a predorsal and postdorsal stripe. The dorsal and caudal fins have very fine melanophores on the rays only. The pectoral fin has similar fine melanophores on its anterior rays only. The anal and pelvic fins are almost unpigmented. The peritoneum is silvery to cream with very few, widely scattered, melanophores.
Paratypes. General characters of the holotype are also found in the paratypes. Measurements are based on 15 fish of each sex, males 36.3–83.7 mm SL and females 36.5–66.0 mm SL. Morphometric data are summarised in Table 1. Males had a significantly larger dorsal-fin base than females while this was reversed for the sexes in the anal-fin base, possibly associated with pair spawning.
The head length is about equal to body depth. The snout is short, its length equals to or slightly smaller than the orbit width. The tip of the mouth cleft is on a level with the upper margin of the pupil in large-sized individuals such that the mouth is slightly superior or somewhat below, at about the level of the middle of the eye, in small-sized ones. The lower jaw projects slightly compared to the upper jaw, often forming a distinct chin especially visible in larger specimens.
There were no significant differences (p>0.05) between males and females for all meristic characters and data for the two sexes were combined. Dorsal-fin with 3 unbranched rays and 7½ (22), 8½ (107) or 9½ (5) branched rays (mean 7.9, standard deviation 0.43); anal fin with 3 unbranched rays and 9½ (14), 10½ (90), 11½ (25) or 12½ (5) branched rays (10.2, 0.65); pectoral fin with 14(4), 15(17) or 16(9) branched rays (15.2, 0.65); pelvic fin with 7(1), 8(27) or 9(2) branched rays (8.0, 0.32); lateral-line scales to hypural fold (in 30 specimens) 45(2), 46(1), 47(3), 48(8), 49(3), 50(1), 51(4), 52(4), 53(2), 54(1), 55(-) or 56(1) (49.5, 2.70); total lateral line scales (in 60 specimens) 45(1), 46(2), 47(3), 48(2), 49(6), 50(14), 51(16), 52(7), 53(5), 54(2), 55(1) or 56(1) (50.5, 2.11); among 134 paratypes there are also 8 specimens with the lateral line widely interrupted (28–40 pored lateral-line scales from 50–53 scales in lateral series); scales around caudal peduncle 14(3), 15(11), 16(13), 17(2) or 18(1) (15.6, 0.90); predorsal scales 23(11), 24(3), 25(5), 26(10) or 27(1) (24.6, 1.38); scales between lateral line and dorsal-fin origin 9(8), 10(17) or 11(5) (9.9, 0.66); scales between lateral line and anal-fin origin 4(6), 5(22) or 6(2) (4.9, 0.51); scales between lateral line and pelvic-fin origin 3(2), 4(17) or 5(11) (4.3, 0.60); total gill rakers 12(2), 13(3), 14(8), 15(10), 16(6) or 17(1) (14.6, 1.22).
Pharyngeal teeth 2.5–4.2 (8) or 2.5–5.2(2), hooked at the tip and strongly serrated below it. The gut is an elongate s-shape. Pigmentation is generally the same as in the holotype except melanophores on the lateral sides of the head are larger and more evident, particularly in the smaller fish.
The sensory canal system was examined in the holotype and 19 paratypes, so the numbers of examined paired canals is 40. The supraorbital canal is not lengthened in its posterior section and has 8–12, commonly 9 or 10 pores (mean 9.6, standard deviation 1.33), with 3 or 4 (3 in 66%) and 5–8 (counts 6 and 7 found each in 30%) canal openings on the nasal and frontal bones, respectively. The infraorbital canal has (14, 15)16–18 pores (a mode of 16 found in 38% of canals; mean 16.6, standard deviation 1.01) with 4 or 5 (in 75%) canal openings on the first infraorbital. The preoperculo-mandibular canal is complete, with 15–17 pores (15 in 58%; 15.5, 0.74) with 4 or 5 (in 83%) and (8)9–10 (9 in 50%) canal openings on the dentary and preoperculum, respectively. It always communicates with the infraorbital canal in the pterotic, passing through the antero-dorsal process of the operculum. The supratemporal canal is complete (60% of specimens) or incomplete, with 4–6 pores.
The total number of vertebrae is 39(2), 40(22), 41(70), 42(35) or 43(5) (41.1, 0.79); the number of abdominal (precaudal) vertebrae includes the Weberian and intermediate vertebrae (those vertebrae that lost articulation with ribs and differ in the degree of transformation of the parapophyses into the haemal arch with the haemal spine); it is 21(39), 22(86) or 23(9) (21.8, 0.56); the number of caudal vertebrae is 18(12), 19(65), 20(53) or 21(4) (19.4, 0.69); and the vertebral formula is 22+19(46), 22+20(28), 21+20(23), 21+19(13), 22+18(9), 23+19(6), 22+21(3), 23+20(2), 21+18(2), 23+18(1) or 21+21(1). The number of predorsal vertebrae (in front of the first dorsal pterygiophore) is 14(51), 15(76) or 16(7) (14.7, 0.57) and the number of intermediate vertebrae is 3(17), 4(69), 5(46) or 6(2) (4.2, 0.65).
Other osteological characters available from the undissected specimens (n=10), the radiographs and three cleared-and-stained specimens are as follows. Maximum cranial width between the lateral margins of the pterotics (Lt pto) is 68–74% of cranial roof length. The supraethmoid is relatively small, its width being 25– 30% Lt pto. The neurocranium is moderately deep, with an angled parasphenoid and a well-defined interorbital septum of the orbitosphenoid. The pharyngeal process has a laterally compressed deep posterior portion. The length of the lower jaw, 32–38% of HL, is smaller than the operculum depth (38–41% HL). The 2nd–4th infraorbitals are narrow. The 5th infraorbital is sometimes absent (on both sides of the head in 2 from 20 examined specimens, and on one side, left or right, in 5 specimens); if present, it is tube-like or has a very narrow lamellate portion. The postcleithrum is reduced to a very small, laterally compressed oval bone with a slightly pointed lower end; it almost entirely adjoins the posterior corner of the cleithrum along its ascending margin. The 2nd and 3rd vertebrae are not fused.
Tubercles on two male fish, 82.5–83.7 mm SL, are fine and scattered on the upper head extending down onto the upper half of the operculum but weak to absent on the snout (Fig. 2). Fine tubercles lining scales are prominent behind the head dorsally but become less evident posteriorly and ventrally. The pectoral fin bears fine tubercles on the anterior rays but numbers decrease to none on more posterior rays.
Etymology. The new species is named after the central Iranian drainage basin which is named for its principal city of Esfahan, the third largest city in Iran.
Distribution and Habitat. The new species is known only from two streams in the Esfahan basin, which has the Zayandeh as its major river (Fig. 4). The Zayandeh and other, smaller rivers and streams of this basin flow from the eastern slopes of the Zagros Mountains to terminate in the salt swamp Gav Khuni. The stream at Dizaj is a southern or right bank tributary of the Zayandeh. The second locality is a stream tributary to the Pelasagan River which flowed into the northern or left bank of the Zayandeh. The Pelasegan now enters the Zayandeh Reservoir.
The type locality was a fresh, clear stream at an altitude of 2300 m. Water temperature at 1705 hours on 9 June was 22°C, pH was 6.2, conductivity was 0.455 mS, stream width was 2–8 m, maximum depth was 1 m, current was slow to moderate, aquatic plant material was of the submergent type, the shore was grassy, and the stream bottom was a mix of pebbles and mud. The second locality was a fresh stream with clear water at an altitude of 2410 m. Water temperature at 1225 hours on 10 June was 17°C, pH was 6.2, conductivity was 0.4 mS, stream width was 4 m, maximum depth was 70 cm, current was slow to moderate, aquatic plant material was of the encrusting type, the shore was grassy, and the stream bottom was a mix of pebbles, sand and mud.
Conservation. Construction of the dam on the Zayandeh River has altered the ecology of the river system but its effects, positive or negative, on the distribution and numbers of the new species is unknown. It may be relatively secure in higher tributary streams. However, demands on water resources from this and other rivers on the central desert plateau of Iran have increased markedly as the human population of the country has doubled in 30 years (from ca. 35 million in mid-1970s to 72 million in 2008, http://en.wikipedia.org/wiki/ Demographics_of_ Iran). Freshwater resources are under threat, exacerbated by droughts, and all species found in these desert or semi-desert areas are under stress.
Comparative remarks. The species is assigned to the genus Petroleuciscus and not to either Squalius or Leuciscus for it shares most of the diagnostic characters of the former (Bogutskaya 2002), namely small size in adults, commonly around 10 – 12 cm (vs. about 20 cm and over in Squalius and Leuciscus); commonly 8½ dorsal-fin branched rays (vs. commonly 7½ in Leuciscus); anal-fin margin convex in its anterior part (vs. analfin margin clearly concave in Leuciscus), and two teeth in the short row (5.2 or 4.2 vs. commonly 5.3 in Leuciscus); few sensory cephalic pores, 8 – 11 in the supraorbital, 14 – 18 in the infraorbital, and 15 – 17 in the preoperculo-mandibular canal (vs. 9 – 14 supraorbital, 16 – 27 infraorbital and 15 – 22 preoperculo-mandibular pores in Squalius); relatively small supraethmoid-mesethmoid block, supraethmoid width less than 30% of cranial roof length (vs. over 36% in Squalius); infraorbitals narrow, posterior margin of fourth infraorbital far from reaching the posterior margin of the preoperculum (vs. broad, posterior margin of 4th infraorbital reaching almost to posterior margin of preoperculum in Squalius); and a deep neurocranium with normally developed interorbital septum (vs. a low neurocranium with low or completely reduced septum in Squalius). However, the new species does not possess a low number of vertebrae typical for most Petroleuciscus species (Table 2; Fig. 3 b −e). The new species is not assigned to the genus Telestes because it differs from the latter by having an indistinct colour pattern with no conspicuous black mid-lateral stripe and/or a conspicuous black dotted line along the lateral line (when preserved) and a broad gold-orange stripe with the lateral line yellow, margined on each side by a narrow black line (in life) characteristic for Telestes (our observations and data from Kottelat and Freyhof (2007)).
The new species is distinguished from all other members of the genus Petroleuciscus by having a high total vertebrae count, modally 41 (vs. 35 – 39) and a high caudal vertebrae count, modally 20 (vs. 15−17) (Table 2, Fig. 3). As can be seen from Table 2, the new species has considerably more vertebrae in all regions than P. persidis (Fars, southern Iran, Fig. 3 e), and smaller lateral-line scales (45−56) than those in P. persidis (35−43). Besides vertebral counts, a terminal or superior mouth with a projecting lower jaw forming a chin is a character that makes P. esfahani sp. n. different from known species of the genus. The only exception is P. gaderanus that we tentatively consider as a synonym of P. ulanus (both are from the Lake Orumiyeh basin in northwestern Iran). The three syntypes of Leuciscus gaderanus (BMNH 1899.9.30.113-115) possess a distinct chin and a straight mouth cleft with the tip of the mouth above the middle of the eye (Fig. 5). Petroleuciscus esfahani sp. n., however, is easily distinguishable from the syntypes of P. gaderanus and P. ulanus (syntypes and additional material as listed below), besides the vertebral counts mentioned above, in having a higher range and modes for anal fin branched rays (9−12½, modes 10−11½ vs. 7−10, mode 9½) and smaller scales (45−56 vs. 36−45).
The new species differs from both P. squaliusculus and P. k u r u i in the shape of the mouth cleft and position of the mouth (an upturned straight mouth cleft with the tip of the mouth on a level with the upper margin of the pupil or only slightly below vs. an oblique curved mouth cleft and the tip of the mouth on the level of the inferior margin of the pupil or below) (P. squaliusculus is shown in Fig. 3 d). It also has more total gill rakers (1217) in contrast to P. k u r u i (11−12). The new species can be further distinguished from P. squaliusculus by having 12−17 gill rakers (vs. 9−11), 45−56 total lateral line scales (vs. 40−47), 9−12½, commonly 10−11½ branched anal fin rays (vs. 7−9½, commonly 8½). Data for some meristic characters other than vertebral counts are summarised in Table 3, and those distinguishing P. esfahani sp. n. from other members of the genus in Iran and the Tigris-Euphrates basin are outlined below in a key.
in species of the genus Petroleuciscus).
Total lateral line Dorsal-fin Anal fin branched Pharyngeal teeth Gill rakers scales branched rays rays
P. esfahani sp.n. 45−56; 50– 51 7−9½; 8½ 9−12½; 10−11½ 2.5–4.2 or 2.5–5.2; 12–17; 15 2.5–4.2
description: Published as part of Coad, Brian W. & Bogutskaya, Nina G., 2010, Petroleuciscus esfahani, a new species of fish from central Iran (Actinopterygii: Cyprinidae), pp. 37-47 in Zootaxa 2534 on pages 38-45, DOI: 10.5281/zenodo.293380