Aphanius mesopotamicus Coad, 2009

Coad, Brian, 2009, A new species of tooth-carp, Aphanius mesopotamicus, from Iran and Iraq (Actinopterygii, Cyprinodontidae), ZooKeys 31 (3), pp. 149-163 : 150-158

Aphanius mesopotamicus Coad , sp. n.

urn:lsid:zoobank.org:act:8B6BFE52-8D1E-45FE-AF41-9BE20C38538D

Type material. Holotype: female, 29.3 mm SL, Iran, Khuzestan, canal branch of Karkheh River , 31°40´N, 48°35´E, 27 January 1978, B. W. Coad and S. Coad ( CM- NFI 1979-0360 A).

Paratypes: 37 (34 used in analyses, smallest male, smallest female and one deformed female not used in analyses), 14 males 17.1–23.9 mm SL and 23 females 14.6-29.1 mm SL, same locality as above ( CMNFI 1979-0360B). 6(4 used in analyses, smallest of each sex not used in analyses), 3 males 17.1–19.9 mm SL and 3 females 15.1-20.5 mm SL, Iran, Khuzestan, Karkheh River branch at Abdolkhan, 31°52'30"N, 48°20'30"E, 27 January 1978, B. W. Coad and S. Coad ( CMNFI 1979–0364). Other, non-type material: 4, 2 males 22.7–24.3 mm SL, 2 females 20.2–25.3 mm SL, Iraq, Qarmat`Ali, Basrah, 30°34'N, 47°46'E, L. A. J. Al-Hassan ( BM (NH) 1982.9.2:326-328).

Comparative material. Aphanius sophiae , material listed in Coad (1996, 1998).

Diagnosis. The new species is defined by pigmentation, distribution, meristics, and in multivariate morphometric and meristic space.

Males of the new species have clear margins to the unpaired fins, no bars on the caudal fin and have 10–15 clearly defined flank bars. Females bear irregular blotches or spots on the flank.

Pigmentation in A. mento and A. dispar , the two other and well-known species in the southern mesopotamian basin of Iraq and Iran, is highly distinctive. A. mento adult males are a dark blue-black with iridescent blue-white to silvery spots. A. dispar males have a caudal fin with 2–3 dark and light blue alternating broad bars, the last bar being yellow.

The new species has been confused with A. sophiae but this species is endemic to an endorheic basin of southern Iran. Females of A sophiae , however, have fine spotting on the flank. Twelve of 14 meristic characters are significantly different for males and 9 of 13 meristic characters for females, although ranges overlap in all cases (Table 5). Discriminant function analyses indicate that the variables with the best discriminating power are pectoral fin rays, scales to pelvic fin, postorbital length and caudal peduncle length in males and pectoral fin rays, scales to pelvic fin, scales to dorsal fin, total scales and predorsal length in females.

The new species is also distinguished from related species in western and southern Iran. Males of A. isfahanensis , a species endemic to an endorheic basin in west-central Iran, have very dark dorsal and anal fin margins. Females of A. persicus , a species endemic to an endorheic basin of southern Iran have thin, distinctive flank bars. Two other species, A. ginaonis , a hot spring endemic of southern Iran, and A. vladykovi , found in the high Zagros Mountains of Iran, are distinguished by non-overlapping meristic characters, respectively higher lateral scale counts (36–47; Coad 1988) and lower dorsal fin ray counts (5–7; Coad 1980).

Description. Meristic characters are summarised in Table 1 and morphometric characters in Table 2 in comparison with A. sophiae . Twelve of 14 meristic characters are significantly different (p<0.05) for males, although ranges overlap, the characters not significantly different being pelvic fin rays counts and precaudal vertebrae. Nine of 13 meristic characters are significantly different (p<0.05) for females, although ranges overlap, the characters not significantly different being anal and pelvic fin rays counts, gill rakers and precaudal vertebrae. Tests for normality and heteroscedasity show that 8 morphometric characters can be compared between species as ratios with t-tests in females but only one in males. Males are more similar morphometrically than females. The 8 significantly different (p <0.05) characters in females are predorsal length, head depth and prepelvic length, all in standard length, and interorbital width, postorbital length, mouth width and anal fin length, all in head length, and head depth in head length. Th e sole male character is head width in head length.

Males are more distinct on the PCA (Fig. 2), where meristic and morphometric values are combined, than females ( Fig. 3 ). The first 5 eigenvectors explain over 57% of total variance for males ( Table 3) and also for females ( Table 4). Discriminant function analyses for males show the variables with the best discriminating power are pectoral fin rays, caudal peduncle length, scales to pelvic fin and postorbital length and for females are pectoral fin rays, scales to dorsal fin, predorsal length and total scales (Table 5).

Description of pigmentation is based on preserved fish only (Fig. 1). Male pigmentation is as follows. The dorsal surface of the head and the upper flank are more heavily pigmented with melanophores than more ventral areas. Th e belly and lower

Figure |. Aphanius mesopotamicus , holotype, female, 29.3 mm SL (CMNFI 1979-0360A) above; paratype, male, 21.7 mm SL (CMNFI 1979–0360B, below).

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Figure 2. Principal components analysis for males of A. mesopotamicus s and A. sophiae k.

head are unpigmented. Th e chin and snout have dense melanophores and a rim of melanophores underscores the eye.

The dorsal, anal and caudal fins in males have wide clear margins. Th is is also seen in the material from Basrah, Iraq (BM(NH) 1982.9.2:326–328). The caudal fin in the type series of the new species is darker just proximal to the clear margin, lighter in mid-fin and dark again at the base. Th e dorsal fin has irregular pigmentation on the membranes and, to a lesser extent, on the rays. Th e pigmentation may involve an overall darker colour in contrast to the light margin or may have some pattern to it. The pattern is often elongate and short blotches with no regular arrangement and sometimes may appear as up to 5 wavy and oblique bands. Dark pigmentation is found just behind the first ray on the fin membrane. Th e anal fin is darkest just proximal to the clear margin. Up to the last 6 membranes of the anal fin are dark and this pigment may be broken up in as many as 4 elongate bars along each membrane. A similar pattern is found in some dorsal fins and the general effect on both fins is that the postero-dorsal (anal fin) and postero-ventral (dorsal fin) parts of these fins are the darkest. The dorsal, anal and caudal fins generally have more pigment on the membranes than the rays and in some this is quite distinctive, making the rays stand out.

The pectoral and pelvic fins in males are generally clear or somewhat milky and opaque and lack melanophores. The distal parts of the membranes between the last 5 rays of the pectoral fin and the small membrane area of the pelvic fins can be pigmented.

Males have flank bars circling the caudal peduncle and reaching the anal fin base but fading ventrally on the lower part of the anterior flank, not reaching the ventral margin of the belly and becoming progressively shorter and less distinct the more anterior they are. Bars are 2–5 times broader than the pale interspaces.

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Figures

Figure 3. Principal components analysis for females of A. mesopotamicus s and A. sophiae k.