Rhodeus caspius, Esmaeili & Sayyadzadeh & Japoshvili & Eagderi & Abbasi & Mousavi-Sabet, 2020

Esmaeili, Hamid Reza, Sayyadzadeh, Golnaz, Japoshvili, Bella, Eagderi, Soheil, Abbasi, Keivan & Mousavi-Sabet, Hamed, 2020, Rhodeus caspius, a new bitterling from Iran (Teleostei: Cypriniformes Acheilognathidae), Zootaxa 4851 (2), pp. 319-337 : 322-334

publication ID	https://doi.org/ 10.11646/zootaxa.4851.2.6
publication LSID	lsid:zoobank.org:pub:589A7843-16F6-4829-A98D-933801B06024
DOI	https://doi.org/10.5281/zenodo.4407967
persistent identifier	https://treatment.plazi.org/id/13C945CB-4147-4BD3-B9CD-CC61189398EB
taxon LSID	lsid:zoobank.org:act:13C945CB-4147-4BD3-B9CD-CC61189398EB
treatment provided by	Plazi
scientific name	Rhodeus caspius
status	sp. nov.

Treatment

Rhodeus caspius , new species

( Figs. 2–11 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURE 11 )

Holotype. ZM-CBSU H1005, 46 mm SL; Iran: Guilan prov.: Shakhraz (=Shakhazar or Siahdarvishan) River, the Anzali Lagoon drainage, the Caspian Sea basin, at Tolamshahr , 37°16’3.98”N 49°21’53.82”E. GoogleMaps

Paratypes. ZM-CBSU H1001, 4, 42–46 mm SL; VMFC RC4 , 4 , 35–42 mm SL; same as holotype. ZM- CBSU H1010 , 1 , 34 mm SL; Iran: Mazandaran prov.: Siah River, near Qaemshahr , 36°26’6.13”N 52°56’58.91”E GoogleMaps ). ZM-CBSU H1011, 2, 36–44 mm SL; Iran: Mazandaran prov.: Tajan River at Goharbaran, the Caspian Sea basin, 36°42’44.3’’N 53°07’51.8’’E GoogleMaps . ZM-CBSU H1013, 2, 31–34 mm SL; Iran: Mazandaran prov.: Babol River, the Caspian Sea basin, 36°30’50.2’’N 52°40’36.2’’E GoogleMaps . ZM-CBSU D193, 1, 37 mm SL; ZM-CBSU D196, 1, 35 mm SL; –ZM-CBSU D199, 1, 28 mm SL; ZM-CBSU D203, 1, 35 mm SL; ZM-CBSU D205, 1, 35 mm SL; Iran: Kordestan prov.: Zarrineh River at Adinan village, Urmia Lake basin, 36°12’13.7’’N 46°25’44.9’’E GoogleMaps .

Material used in the molecular genetic analysis. Rhodeus caspius: ZM-CBSU M 526; Iran: Kermanshah prov.: Razavar River at Qazanchi village, Tigris GoogleMaps basin, 34°26’40.5’’N 47°01’30.1’’E (GenBank accession numbers: MT 878140 View Materials ). ZM-CBSU M527; Iran: Kermanshah prov.: Kamiaran River at Kamiaran, the Tigris basin, 34°48’00.34’’N 46°56’27.65’’E (GenBank accession numbers: MT 878141 View Materials ) GoogleMaps . ZM-CBSU M1303; Iran: Mazandaran prov.: Babolrud River, Caspian Sea basin, 36°30’50.2’’N 52°40’36.2’’E. (GenBank accession numbers: MT 878142 View Materials ) GoogleMaps . IMNRFI-UT 24A; Iran: Guilan prov.: Anzali Lagoon, the Caspian Sea basin, 37°26’21”N 49°27’21”E (GenBank accession numbers: MT 878143 View Materials ) GoogleMaps . IMNRFI-UT 22B; Iran: Mazandaran prov.: Babol River, Caspian Sea basin, 36°30’50.2’’N 52°40’36.2’’E (GenBank accession numbers: MT 878144 View Materials ) GoogleMaps . IMNRFI-UT 23 T; Iran: Mazandaran prov.: Tajan River, Caspian Sea basin, 36°42’44.3’’N 53°07’51.8’’E (GenBank accession numbers: MT 878145 View Materials ) GoogleMaps .

Rhodeus colchicus: ZM-CBSU M2487 , M2490, M2491, M2492; Georgia: Samegrelo GoogleMaps : Khobi River, Black Sea basin, 42° 15’ 50.7708’’ N 41° 46’ 4.242’’ E (GenBank accession numbers: MT 878146 View Materials , MT 878147 View Materials , MT 878148 View Materials , MT 878149 View Materials ).

Diagnosis. Rhodeus caspius sp. nov. is distinguished morphologically from its closest species, R. amarus by having short post-dorsal distance (28–30 vs. 31–34% SL); and from R. colchicus by having long caudal peduncle length (26–30 vs. 23–25% SL) and head length (27–30 vs. 25–26% SL). It is also characterized by one fixed diagnostic nucleotide substitutions and a K2P nearest neighbor distance of 1% to R. amarus and R. colchicus in the mtDNA COI barcode region ( Table 2). Based on Bogutskaya & Komlev (2001), Rhodeus colchicus is distinguished from congeners by a suite of characters which includes large scales (34 to 37, commonly 35, in the lateral row), commonly 9 branched rays in both the dorsal and anal fins, a low number of vertebrae (33 to 36, commonly 35, total, and 16 to 18, commonly 17, in the abdominal region), a deep shortened second infraorbital, a broad fourth infraorbital and a well-developed fifth one with a widened lamellate portion.

Rhodeus caspius sp. nov. is distinguished from R. meridionalis by having a subinferior mouth (vs. terminal), upper lip covered completely or more than half (vs. rostral cap covering upper part of upper lip (according to Kottelat & Freyhof 2007)) and low number of pored scales in lateral line (3–8, usually 6 vs. 11 (according to Karaman (1924)).

In the R. sericeus group, R. caspius sp. nov. is distinguished from R. sericeus by having low number of scales in lateral series (34–37 vs. 36–40 according to Holcik & Jedlicka 1994).

Rhodeus caspius sp. nov. is distinguished from Rhodeus sinensis which was formerly placed in R. sericeus as a subspecies, by having low number of branched dorsal fin rays 9–10, usually 9 (vs. 12–13, based on Bogutskaya & Komlev 2001), low number of branched anal fin rays 8–9, usually 9 (vs. 10, based on Bogutskaya & Komlev 2001), higher number of gill rakers 10-13 vs. 6–7, based on Arai et al. 2001), and low range of maximum body depth (35–39 vs. 32–55, based on Arai et al. 2001).

Rhodeus caspius sp. nov. is distinguished from R. pseudosericeus , another species in the Rhodeus sericeus group, by low number of anal fin branched ray (8–9 usually 9 vs. 9–11, mode 10 based on Arai et al. 2001), iris color of males (bright red vs. blackish).

Rhodeus caspius sp. nov. differs from the R. smithii complex including R. smithii (Regan, 1908) , R. notatus Nichols, 1929 , R. suigensis (Mori, 1935) , R. atremius ( Jordan & Thompson, 1914) and R. fangi (Miao, 1934) , distributed in China, Korea, and Japan, in the gill raker number on the outer side of the first gill arch (10-13, vs. 4–8, based on Arai et al. 2001).

Rhodeus caspius sp. nov. is distinguished from R. ocellatus by having lower number of branched dorsal fin ray [(9–10, usually 9 vs. 10-12 (according to Kottelat & Fryhof (2007))], and females and juveniles with a black blotch in anterior part of dorsal (vs. no blotch).

Rhodeus caspius sp. nov. is also distinguished from East Asian Rhodeus species. Rhodeus caspius sp. nov. is distinguished from R. albomarginatus Li & Arai, 2014 from the Lvjiang River, a tributary flowing into Poyang Lake of Yang-tze River basin, in Anhui Province, China by branched anal-fin rays 9–10, usually 9 (vs. modally10–11 based on Li & Arai 2014); and colour pattern of adult males (dorsal and anal fins of males edged with black margin vs. white margin, according to Li & Arai (2014)).

Rhodeus caspius sp. nov. is also distinguished from R. shitaiensis Li & Arai, 2011 by usually low number of pored scale (3–8 vs. 6–12) and transverse scale 10-12 (vs. 10 according to Li & Arai (2011)).

Rhodeus caspius sp. nov. is distinguished from R. haradai Arai, Suzuki & Shen, 1990 , R. spinalis Oshima, 1926 , from southern China ( Arai et al. 1990), and R. laoensis Kottelat, Doi & Musikasinthorn in Kottelat (1998) from Laos, in having fewer anal fin branched rays (8–9 usually 9, vs. more than 11, based on Arai et al. 2001).

Rhodeus caspius sp. nov. differs from R. rheinardti (Tirant, 1883) from Vietnam in having fewer dorsal (9–10, usually 9, vs. 12–13) and anal fin branched rays (8–9 usually 9, vs. 13–14, based on Arai et al. (2001)).

Description. For general appearance and morphometric data see Figures 2–4 View FIGURE 2 View FIGURE 3 View FIGURE 4 and Table 3–4. Small sized and deep and compressed body species with short head. Head length 27–30% SL, considerably less than the maximum body depth, 34–42% SL. The greatest body depth at dorsal-fin origin and shallowest near caudal-fin base. Dorsal body surface profile convex and ventral body surface profile rounded. Snout usually shorter than eye diameter (22–30 and 28–35% HL, respectively). Mouth sub-inferior. Lower lip well developed but not thick, not interrupted in the middle. Barbels absent. Dorsal fin with 3 simple and 9–10 (usually 9) branched rays. Anal fin with 2–4 (usually 3) simple and 8–9 (usually 9) branched rays. Pectoral fin with 10-12 (usually 12) rays. Pelvic fin with 7–8 (usually 8) rays. Caudal fin forked with 9 + 8 branched rays; its lobes rounded distally; lobes nearly equal in length. First simple rays of dorsal and anal fins very small, embedded under scales at base. Longest simple ray of dorsal fin strong and stiff, distally segmented; width of basal part about twice that of first branched dorsal-fin ray base. Body covered with large cycloid scales. Lateral line incomplete: pored scales 3–8, usually 6. Longitudinal scale series 34–37. Transverse scale rows 10-12. Predorsal scale rows 14–16 including one deeply notched in front of first dorsal fin ray. Scale rows around caudal peduncle 12–14. Cephalic sensory canals ( Fig. 4 View FIGURE 4 ) categorized as Type II with incomplete infraorbital canal (IOC). Supraorbital canal pores (SOC) 6–8; infraorbital + temporal canal pores (IOC+TC) 10-15; preopercular + mandibular canal pores (PC+MC) 8–11 and supratemporal canal pores (STC) 0-4 ( Table 4). Dark spot on scales behind gill cleft. Total vertebrae 35–36. Gill rakers on external side of first gill arch 10-13. Pharyngeal teeth in one row, 0.0.5–5.0.0. A developed ovipositor in females during breeding season.

Osteological characteristics ( Figs. 5–11 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURE 11 ). In ethmoid region of neurocranium, supraethmoid with two horizontal and vertical portions; horizontal part wider possessing three posterior lobes; presence of two small processes in vertical part of supraethmoid-ethmoid with two small nasals positioned on its lateral sides; lateral ethmoid blade-shaped; vomer V-shaped anteriorly and pointed posteriorly; two cartilaginous preethmoid I in antero-lateral part of vomer; In in orbital region, frontal wide posteriorly with two lateral pointed process; two oval supraorbitals located on antero-lateral part of frontal; orbitosphenoid blade-shaped; ptersphenoid situated between orbitosphenoid and sphenotic; anterior and posterior half of parasphenoid elongated with two central wings bended dorsally; circumorbital series with four infraorbital, one supraorbital and lachrymal elements. In otic region, epiotic almost circular in shape; pterotic oval in shape the parietal tetragonal with its edges overlaping frontal, pterotic, epiotic and supraoccipital; sphenotic with an anteroventral pointed process fused to posterolateral process of frontal; ventral edge of prootics connected to each other. In occipital region, supraoccipital with a triangular crest. In ventral view, exoccipital almost L-shaped; lateral margin of basioccipital reclined dorsally having a pharyngeal process with a ventral process.

Upper jaw with two paired maxillaries and premaxillaries; anterior part of maxillary broader having a developed mid-dorsal ascending process; anterior part of premaxillae possessing rostral ascending process with posterior narrower part. In suspensorium, dorsal part of hyomandibular wider; dorsal process of metapterygoid triangular and bended medially; endopterygoid with a pointed process just above its facet; ectopterygoid under anteroventral side of endopterygoid; quadrate with two dorsal and ventral portions; symplectic elongated and narrow and anterior part of palatine pointed bearing two dorsal and one ventral processes. In opercular series, anterior part of subopercle wider bearing an anterodorsal small process; interopercle with a knife-like shape overlapping with ventral part of crescent shaped interopecle.

In hyoid arch, narrow basihyal with a ventral blade-shaped process; urohyal with two horizontal and vertical parts; posterior part of ceratohyal wider and epihyal triangular in shape and a small interhyal bone located on its posterior part; hypohyal with two paired dorsal and ventral elements. Three pairs of branchiostegal rays, branchial apparatus with four pairs of ceratobranchial, four pairs of epibranchial, three pairs of hypobranchial, two pairs of oval shaped pharyngobranchial and three unpaired basibranchial bones. Pharyngeal teeth in a row with a dental formula of 5-5. Pectoral girdle with an almost L-shaped cleithrum having a large and narrow postcleithrum in its rear; coracoid triangular in shape connecting to cleithrum with a spiral mesocoracoid; scapula broadened ventrally and pointed dorsally with a large foramen in its middle part; supracleithrum narrow, attached to a triangular-shaped posttemporal dorsally; four radials in pectoral fin. In pelvic girdle, paired anteriorly bifurcated basipterygium attached to each other; L-shape paired lateral-pterygium positioned in lateral side of basipterygium and three pairs of meta-pterygium located behind it.

Dorsal fin with 3 unbranched and 9½ branched rays, 10 pterygiophores and one stay; first dorsal pterygiophore adjacent to 11 th or12 th vertebra; 7–8 supraneurals in front of dorsal fin; anal fin with 3 unbranched and 9½ branched rays (10½ found in one species), 10 pterygiophores and a small stay, first pterygoid is next to 18 th or 19 th vertebra. 35–36 vertebrae in axial skeleton. Caudal fin forked, and its skeletal structure including epural, parahypural, pleurostyle, uroneural and six hypurals bones. Caudal fin with 19 branched rays and various numbers of procurrent rays.

Sexual dimorphism. The female has an ovipositor near the genital opening; males develop tubercle-bearing scales on the snout, mature males are colorful during the spawning season.

Coloration. Adult males are especially colorful in the spawning season: Dorsal surface of head and back olive to bright green, reddish or dark violet, iris bright red, flanks iridescent with violet and steel-blue colors most evident, throat and belly orange to red, anal fin bright red and margined with black, a well-pronounced bright red spot on the first four rays of dorsal fin, caudal fin bright green at the base and yellow distally, pectoral and pelvic fins yellowish with dark pigments specially on pelvic fin membranes, females more yellowish and less iridescent than males in the spawning season, both sexes similar in color with a grey-green back, silvery flanks and yellowish belly outside the breeding season, a grey-green to greenish-blue stripe originates under the dorsal fin and extends back to the tail base, broadening posteriorly being broader in males, the dorsal fin blackish and other fins reddish to yellowish, the dorsal, and sometimes the anal fin, with a dark interrupted stripe, the iris silvery or yellowish.

Distribution. Rhodeus caspius sp. nov. is originally known from the Caspian Sea basin but it has been translocated to two the Tigris River drainage and Urmia Lake basin ( Fig. 12 View FIGURE 12 ).

Habitat. Rhodeus caspius sp. nov. favors heavily vegetated areas of lakes, ponds and slow-running rivers, rarely in the faster waters. It is found in the lower reaches of rivers on the Caspian Sea coast, Urmia Lake and Tigris River drainage of Iran ( Fig. 13 View FIGURE 13 ).

Biology. Reproductive season in the Siah River from March to June, peaking in April, average absolute fecundity 329.74 eggs and average relative fecundity 187.4 eggs/g based on Patimar et al. (2010). Average number of eggs 78.8 for examined fishes from the Sefid River ( Norouzi & Abbasi 2015). Ovipositor length up to 126.5% of standard length in the Anzali Lagoon in April (Holcik in Bănărescu 1999). Maximum life span 8–9 years ( Norouzi et al. 2014, Norouzi & Abbasi 2015).

Mirhashemi Nasab et al. (2017) reported a trematode worm Diplostomum spathaceum in fish from the Anzali Lagoon with a prevalence of 18.18% and a range of 1–4 worms per fish.

Etymology. The species is named for the Caspian Sea basin where the type materials were collected.