Aphanius arakensis Teimori, Esmaeili, Gholami, Zarei & Reichenbacher 2012

The Arak toothcarp (Aphanius arakensis) is a species of pupfish belonging to the family Cyprinodontidae. Discovered in 2012, it is endemic to the Namak Lake basin in Iran.

The males of the new species reach approximately 32 mm SL and have 12–19 flank bars, the females are usually larger than the males and reach approximately 34 mm SL. The morphometric characters are summarized in Table 1. Compared to the other examined Aphanius species, Aphanius arakensis sp. n. shows higher mean values of the minimum body depth, width and length of scales, distances between the pectoral and pelvic fins and the interorbital distance, but significantly lower mean values for the eye diameter and the caudal peduncle length (differences are statistically significant, p < 0.05). The meristic characters are summarized in Table 2. The dorsal fin is characterized by a somewhat curved superior border, and has 11–14 rays; the anal fin shows a round superior border and includes 10–12 rays; the pectoral fin is rounded and consists of 14–18 rays; the pelvic fin is relatively short, positioned just anteriorly to the anal fin and comprises 6–8 rays. The caudal fin is rounded; the caudal peduncle possesses 10–13 scales. The number of lateral line series scales is 27–32. However, the ANOVA analysis reveals that only the numbers of lateral line series scales and caudal peduncle scales (in males and females), as well as the numbers of flank bars (in males), significantly differ from the values obtained for the other examined species. Moreover, there is a significant correlation between SL and numbers of flank bars (Pearson Correlation r = 0.455, p < 0.05*). The otolith is rounded-trapezoid and characterized by a very wide excisura, a medium-sized and pointed rostrum, and a quite short antirostrum. The ventral and dorsal rims are slightly curved; the ventral rim may bear small irregular processes; the dorsal rim may show a fine crenulation; the posterior rim is steep (Fig. 3W-Aa). The flank bars in males (Fig. 2a) are narrow and the interspaces are broader than the bars. The first bar is located above the operculum, while the posteriormost bar is located at the base of the caudal fin; the interspaces are wider at the caudal peduncle than in the anterior body part. Dorsally, the head is gray and the body is dark due to a strong melanophore pigmentation. The ventral body portion does not usually show any dark pigmentation. The dorsal, anal and caudal fins have white margins; the first rays of the dorsal fin are dark. The pectoral fins are somewhat yellowish. The pelvic fin is yellowish. Most specimens are characterized by dark blotches at the base of the dorsal and anal fins. Females (Fig. 2b) are characterized by a grayish pigmentation of the back. The lateral flanks of the body are covered by dark pigmentations; series of blotches are present from the middle of the body to the caudal peduncle. The ventral part of the head and belly are light. The chin and sides of the head are speckled with melanophores. Below the eye there is a line of relatively dark melanophores. All fins are white. Meristic characters (mean ± standard deviation and range) of Iranian Aphanius species. Character Aphanius arakensisn=35, male Aphanius arakensisn=35, female Aphanius isfahanensisn=18, male Aphanius isfahanensisn=25, female Aphanius sophiaen=35, male Aphanius sophiaen=35, female Aphanius farsicusn=35, male Aphanius farsicusn=35, female Aphanius vladykovin=35, male Aphanius vladykovin=35, female Aphanius pluristriatusn=32, male Aphanius pluristriatusn=38, female Dorsal fin rays 12.2±0.8(11–14) 12.3±0.7(11–14) 11.7±0.6(11–13) 11.6±0.7(10–13) 13.7±0.6(13–15) 13.8±0.8(13–15) 12.1±0.8(11–14) 12±0.8(10–13) 13.2±0.8(12–15) 13.5±0.7(12–15) 13.8±0.7(12–15) 13.6±0.7(12–15) Pectoral fin rays 16.7±0.9(14–18) 16.8±0.6(16–18) 15.9±0.8(15–17) 16.3±0.5(15–17) 18±0.8(16.20) 17.9±0.7(17–19) 15.4±0.7(14–17) 15.4±0.6(14–17) 16.5±0.8(14–18) 16.6±0.7(15–18) 17.1±0.7(16–19) 17±0.6(16–18) Pelvic fin rays 7.3±0.5(6–8) 7.2±0.4(7–8) 7±0.6(6–8) 6.9±0.5(6–8) 7.3±0.5(6–8) 7.3±0.6(6–8) 6.7±0.4(6–7) 6.6±0.5(5–7) 7±0.6(6–9) 6.9±0.4(6–8) 7.2 ±0.5(6–8) 7.1± 0.4(8–7) Anal fin rays 11.4±0.5(10–12) 11.5±0.5(11–12) 10.9±0.3(10–11) 11.1±0.5(10–12) 12.3±0.6(11–14) 12.7±1.1(12–17) 11.1±0.6(10–12) 11.1±0.7(10–12) 13.2±0.7(12–15) 13.2±0.8(12–15) 13±0.7(12–14) 12.5±0.611–14 Lateral line series scales 30.1±1.0(29–32) 29.6±1.1(28–32) 24.9±1.5(23–27) 26±1.4(23–27) 27.9±0.9(26–29) 27.1±1.3(25–29) 25.6±1.6(22–28) 25.4±1.5(23–29) 36.3±2.8(33–43) 37.1±2.7(33–43) 27.1±1.1(24–29) 27±1.2(24–29) Caudal peduncle scales 11.6±0.6(10–13) 11.6±0.7(10–13) 10±0.5(9–11) 10.3±0.8(9–12) 9.9±0.8(8–11) 9.7±0.6(9–11) 9.26±0.6(8–11) 9.4±0.6(8–10) 12.6±1.1(10–14) 12.5±1.4(9–15) 9.2±0.7(8–11) 9.3±0.8(8–11) Gill raker 9.2±0.5(8–10) 9.3±0.5(8–10) 10.8±0.5(10–12) 11.1±0.7(10–13) 10.7±0.7(9–12) 10.7±0.8(9–12) 10.9±0.7(9–13) 10.7±0.8(9–12) 9.7±0.1(8–12) 9.7±0.7(8–11) 9.8±0.6(8–11) 9.6±0.7(8–11) Flank bars 15.9±1.4(12–19) – 10.7±0.9(9–13) – 11.9±1.5(8–15) – 12.4±1.2(10–16) – 11±1.2(8–13) – 13.8± 1.7(11–17) –

The species has been collected from a small natural shallow pond (Fig. 4) in the Namak Lake basin, 5 km south east of the city of Arak (Fig. 1). This pond, which is about 6 x 4 m in size, is fed by the drainage of a nearby natural spring. During sampling, the water body was almost stagnant and water temperature was 23°C. There was no vegetation in the pond, but the surrounding area was covered with Juncus sp. and Typha sp. The bottom of the pond was generally muddy with small gravels. The habitat was in a bad condition due to anthropogenic pollution. Around collection time, the new Aphanius species was the only fish observed living in the pond. In addition, the new species can be found in several springs located in close proximity to the type locality (Fig. 5).