A new species of the genus Capoeta Valenciennes, 1842 from the Caspian Sea basin in Iran (Teleostei, Cyprinidae)

Abstract A new species of algae-scraping cyprinid of the genus Capoeta Valenciennes, 1842 is described from the Kheyroud River, located in the southern part of the Caspian Sea basin in Iran. The species differs from other members of this genus by a combination of the following characters: one pair of barbels; predorsal length equal to postdorsal length; maxillary barbel slightly smaller than eye’s horizontal diameter and reach to posterior margin of orbit; intranasal length slightly shorter than snout length; lateral line with 46–54 scales; 7–9 scales between dorsal-fin origin and lateral line, and 6–7 scales between anal-fin origin and lateral line.

Capoeta species mainly inhabit fast flowing streams and rivers, but some species may also be found in lakes and springs (Turan et al. 2006). The members of this genus possess a fusiform body with small to moderately large scales and an inferior mouth (Coad 2017). Their lower lip bears a keratinized edge and lower lip is restricted to the corner of mouth (Howes 1982;Turan et al. 2006;Coad 2017). The dorsal fin is short with the last unbranched ray thickened, and has serrations posteriorly (serrations sometimes reduced to absent).
The populations of the genus Capoeta from the southern Caspian Sea basin are considered as belonging to two different species: C. gracilis and C. capoeta (Esmaeili et al. 2010;Jouladeh-Roudbar et al. 2015b). Capoeta gracilis was originally described from rivers near Esfahan, central Iran (Esfahan basin) and C. capoeta from Tiflis (Caspian Sea basin), Georgia (the Caspian Sea basin) (Güldenstädt 1773;Temminck and Schlegel 1843;Coad 2017). Several authors have considered C. gracilis as subspecies of C. capoeta, both with allopatric distribution. Capoeta c. gracilis was restricted to rivers between the Sefid and Atrak rivers in the southern part of the Caspian basin in Iran and C. c. capoeta to the Kura-Aras basin in western part of the Caspian basin (Bianco and Banarescu 1982). Furthermore, Bănărescu (1999) restricted the distribution of C. c. gracilis to the Urmia Lake basin and the Sefid River in southern part of the Caspian basin (and also to the lower Kura River in Azerbaijan) while C. capoeta aff. gracilis (an unnamed subspecies related to C. c. gracilis) was considered to inhabit the rest of the Iranian Caspian shore (Jouladeh-Roudbar et al. 2015). Posterior works have considered C. gracilis as a valid species but its distribution has been controversial (Esmaeili et al. 2014).
Currently, molecular studies have shown a high genetic differentiation in the populations of southern Caspian basins considered previously as C. gracilis or C. c. aff. gracilis and this led to the consideration of these populations as an undescribed species (Levin et al. 2012;Ghanavi et al. 2016). The presence of C. capoeta in both the Cas-pian Sea and Urmia Lake basins was also confirmed based on molecular and morphological data (Ghasemi et al. 2015;Ghanavi et al. 2016).
Previous phylogenetic and phylogeographic studies based on molecular mitochondrial data recognized three main clades within the genus Capoeta, Mesopotamian clade, Aralo-Caspian clade, and Anatolian-Iranian clade (Levin et al. 2012;Ghanavi et al. 2016). The Aralo-Caspian clade is composed by four valid species i.e. C. capoeta, C. heratensis, C. fusca and C. alborzensis in the Iranian freshwater basins Jouladeh-Roudbar et al. 2016). A detailed study of the populations of Aralo-Caspian clade in Iran, found some populations of the genus Capoeta, which were not identified as any described species ). Among them were populations distributed in the southern Caspian Sea basin, traditionally identified as C. gracilis (Jouladeh-Roudbar et al. 2015b). Our collection of the genus Capoeta from the southern Caspian Sea basin revealed the presence of two species, i.e. C. capoeta and an undescribed species (considered as Capoeta sp.1 in Ghanavi et al. 2016) that differ molecularly and morphologically from other described Capoeta species including species from the Esfahan basin (Alwan et al. 2016;Ghanavi et al. 2016). According to our intensive samplings from the Esfahan basin, only two species i.e. C. aculeata and C. coadi were found. Therefore, the main goal of this work is to study morphologically the populations of the collected Capoeta specimens from the southern Caspian Sea basin, north of Iran, previously assigned to C. gracilis, and to compare them with the remaining species of this genus from Iran, and based on differences found, they are described as a new species herein.

Materials and methods
Approximately 150 specimens of the genus Capoeta were collected by electrofishing at 14 sites covering most of its distribution area in southern Caspian Basin ( Figure 1, Table 1). Fin clips stored in 96% ethanol and deposited in the Tissue and DNA Collection of the Ichtyological Museum of Natural Resources Faculty -University of Tehran (IMNRF-UT). The fish were killed with overdoses of MS222, were fixed in 10% formalin, and were later preserved in the Ichthyology collection of IMNRF-UT, Iran. For morphometric purposes and to have a base for molecular studies 23 individuals of C. capoeta and C. fusca from the Urmia Lake and Hari River basins, respectively, were also analysed.
Morphological examinations. Thirty morphometric measurements and thirteen meristic character countings were performed using a digital caliper to the nearest 0.1 mm and stereomicroscope, respectively (Tables 4-8). Measurements follow Kottelat and Freyhof (2007). Fin ray counts separate unbranched and branched rays. The last two branched rays articulated on a single pterygiophore in dorsal and anal-fins are noted as "1".
An allometric method was used to remove size-dependent variation in morphometric characters using following formula (Elliott et al. 1995): M adj = M(L s /L 0 ) b , where M is the original measurement, M adj the size adjusted measurement, L 0 the standard length of the fish, L s the overall mean of the standard length for all fish from all samples in each analysis, and b was estimated for each character from the observed data as the slope of the regression of log M on log L 0 using all fish in any group. The adjusted morphometric characters of the studied populations were analysed using Principal Component Analysis (PCA) and compared by Non-Parametric Multivariate Analysis of Variance (NPMANOVA) based on the P-values obtained from permutation test with 1000 replicates in PAST software (version 2.14). The meristic characters of the studied populations were analysed using Correspondence Analysis (CA), and compared by Non-Parametric Multivariate Analysis Of Variance (NPMANOVA) based on the Bonferoni-corrected P-values obtained from permutation test with 1000 replicates in PAST software (version 2.14).

SL
standard length; HL lateral head length; IMNRFI-UT Ichtyological Museum of Natural Resources Faculty.
Diagnosis. Capoeta razii sp. n. is distinguished from the other species of Capoeta in Iran by a following combination of characters, none of them unique. One pair of barbels; pre-dorsal length equal to postdorsal length; maxillary barbel slightly smaller than eye's horizontal diameter and reach to posterior margin of orbit; intranasal length slightly shorter than snout length; lateral line with 46-54 scales, 7-9 scales between dorsal-fin origin and lateral line and 6-7 scales between anal-fin origin and lateral line.
Description. See Figure 4 for general appearance and Tables 4-7 for morphometric and meristic data. Body is moderately deepened and compressed laterally. Greatest body depth occurs at the level of dorsal-fin origin. Dorsal profile of the head is convex. Predorsal length is equal to post-dorsal length. Dorsal profile of the body is convex without any keel in the front of dorsal-fin origin. Snout is rounded with a triangular view in ventral. Mouth is almost straight. Upper and lower lips are adnate to jaws. Lower jaw has a strong keratinized edge. Rostral cap is well developed and usually overlaps with upper lip. One set of maxillary barbels that are short, slightly smaller than eye's horizontal diameter, reaching to posterior margin of orbit. Intranasal length is slightly shorter than snout length. Pelvic axillary scales are triangular, well developed, and pointed. Dorsal   Caudal peduncle depth 12.1 11.1-12.9 11.9 0.5 10.1-12.6 11.7 0.7 11.1-13.5 12.5 0.     fin has 3-4 unbranched and 7-8 branched rays, its outer margin is straight or slightly concave. Last unbranched dorsal-fin ray is thickened and serrated, distally flexible, and with 15-25 serrae on its posterior margin, with serrations along 50-70% of its posterior margin, denticles are long and narrowly spaced but not strongly developed. Last unbranched dorsal-fin ray slightly shorter than first branched ray, and the tip is soft. Pelvic fins are inserted under posterior of the first branched dorsal-fin base. Caudal fin is deeply forked with pointed and equal size of lobes. Pectoral fin has 16-19 branched rays. Pelvic fin has 1 unbranched and 9-10 branched rays. Anal fin has 2-3 unbranched rays, 6 branched rays and its outer margin is usually convex or straight. There are 15-21 gill rakers on the outer side of the first arch. There are 17-18 circum-peduncular scales. Lateral line is complete, with 46-54 scales. There are 7-9 scales between the dorsal-fin origin and lateral line and 6-7 are located between the anal-fin origin and lateral line.   Colouration. In life, the upper part of the body is golden brown, olive-green, or silver, and the belly is whitish up to the lateral line. The head is dark-brown or olivegreen on top and the cheeks are pale brown to white (Figure 4). Anal, pelvic, and pectoral fins are hyaline or light brown, and dorsal and caudal fins have a narrow black line on rays. In specimen smaller than 50 mm SL, minute black spots are present on flanks.
When preserved, the dorsum is dark brown on back and flanks, and yellowish white on belly ( Figure 6). Dorsum of the head is dark brown, and the cheeks beige. Fins are often light brown and pelvic and anal fins may be yellowish to hyaline. Dorsal and caudal fins are darker than lower fins. Peritoneum is black.
Distribution and habitat. Capoeta razii is found in many rivers and streams of the southern Caspian Sea basin. It is one of the most abundant species in the Caspian Sea basin along with the members of the genus Alburnoides Jeitteles, 1861. At the Kheyroud River (type locality), the current was medium to fast, river width was between 3-14 m and the maximum depth was around one meter, the stream bed was composed of cobbles and gravel, and the riparian vegetation type was deciduous forests. Following fish