A new species of tooth-carp, Aphanius mesopotamicus, from Iran and Iraq (Actinopterygii, Cyprinodontidae)

A new species of tooth-carp, Aphanius mesopotamicus (Cyprinodontidae), is described from southern Mesopotamia in Iran and Iraq. It is distinguished from related species by pigmentation (males have clear margins to the unpaired fi ns, no bars on the caudal fi n and 10–15 clearly defi ned fl ank bars; females bear irregular blotches or spots on the fl ank), distribution, and a suite of morphometric and meristic characters in multivariate space (pectoral fi n rays, caudal peduncle length, scales to pelvic fi n and postorbital length in males and pectoral fi n rays, scales to dorsal fi n, predorsal length and total scales in females). Th e description is based on museum specimens and there have been no recent collections of the new taxon.


Introduction
Th e taxon Aphanius sophiae (Heckel 1849) has been widely used as the name of toothcarps in various basins in southern Iran and Iraq, and even the Middle East generally. However, this species is restricted to the endorheic Kor River basin north of the city of Shiraz in Fars Province, Iran (Coad 1996). Studies over the past 20 years have demon-strated that a series of species exist in endorheic and exorheic basins of Iran as relicts of the Tethys Sea. Th ey were initially recognized by their allopatric distributions and distinct pigment patterns and, later, in some cases by meristic characters, and in other cases principally by molecular characters (Coad 1988(Coad , 2000Hrbek et al. 2006).
Th e purpose of this paper is to describe a new species from Iran and Iraq in the Persian Gulf drainage.

Material
Th e type material is housed in the collections of the Canadian Museum of Nature, Ottawa (CMNFI). Comparative material is in the Natural History Museum, London (BM(NH)) and the Zoological Institute, St. Petersburg (ZISP).

Methods
Measurements and counts follow Coad (1988Coad ( , 1996. A set of 14 meristic counts summarised in Table 1 and of 22 standardized measurements (Table 2) were collected for all specimens.
Flank or cross-bar counts were taken by counting the number of dark bars (males only) on the mid-lateral series of scales on the left side.
Data ordination combining morphometric and meristic analyses follows Coad (1996). Principal components analysis (PCA) was done on a correlation matrix incorporating log-transformed, standardized size-free variates and untransformed meristic data using SYSTAT (SYSTAT, 2005). Discriminant function analysis (DFA) was used to identify characters that contributed most to group diff erentiation.
Males of the new species have clear margins to the unpaired fi ns, no bars on the caudal fi n and have 10-15 clearly defi ned fl ank bars. Females bear irregular blotches or spots on the fl ank.
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 fi n with 2-3 dark and light blue alternating broad bars, the last bar being yellow.
Th e 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 fi ne spotting on the fl ank. Twelve of 14 meristic characters are signifi cantly diff erent 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 fi n rays, scales to pelvic fi n, postorbital length and caudal peduncle length in males and pectoral fi n rays, scales to pelvic fi n, scales to dorsal fi n, total scales and predorsal length in females.
Th e 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 fi n margins. Females of A. persicus, a species endemic to an endorheic basin of southern Iran have thin, distinctive fl ank 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 fi n 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 signifi cantly diff erent (p<0.05) for males, although ranges overlap, the characters not signifi cantly diff erent being pelvic fi n rays counts and precaudal vertebrae. Nine of 13 meristic characters are signifi cantly diff erent (p<0.05) for females, although ranges overlap, the characters not signifi cantly diff erent being anal and pelvic fi n 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. Th e 8 signifi cantly diff erent (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 fi n 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). Th e fi rst 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 fi n rays, caudal peduncle length, scales to pelvic fi n and postorbital length and for females are pectoral fi n rays, scales to dorsal fi n, predorsal length and total scales ( Table 5).
Description of pigmentation is based on preserved fi sh only (Fig. 1). Male pigmentation is as follows. Th e dorsal surface of the head and the upper fl ank are more heavily pigmented with melanophores than more ventral areas. Th e belly and lower Th e dorsal, anal and caudal fi ns in males have wide clear margins. Th is is also seen in the material from Basrah, Iraq (BM(NH) 1982.9.2:326-328). Th e caudal fi n in the type series of the new species is darker just proximal to the clear margin, lighter in mid-fi n and dark again at the base. Th e dorsal fi n 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. Th e 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 fi rst ray on the fi n membrane. Th e anal fi n is darkest just proximal to the clear margin. Up to the last 6 membranes of the anal fi n 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 fi ns and the general eff ect on both fi ns is that the postero-dorsal (anal fi n) and postero-ventral (dorsal fi n) parts of these fi ns are the darkest. Th e dorsal, anal and caudal fi ns generally have more pigment on the membranes than the rays and in some this is quite distinctive, making the rays stand out.
Th e pectoral and pelvic fi ns in males are generally clear or somewhat milky and opaque and lack melanophores. Th e distal parts of the membranes between the last 5 rays of the pectoral fi n and the small membrane area of the pelvic fi ns can be pigmented.   Males have fl ank bars circling the caudal peduncle and reaching the anal fi n base but fading ventrally on the lower part of the anterior fl ank, 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.
Females have a similar head and dorsal and ventral body pigmentation but it is much lighter than in males. Fins have little or no pigmentation. Th e proximal third to half of the dorsal fi n rays and membranes, particularly the anterior ones, have pigment in some fi sh but this is weakly expressed compared to the condition in males. Some fi sh have a few faint melanophores lining the anal fi n rays.
Th e most distinctive feature in these females is a spot, oval to lozenge-shaped, at the central base of the caudal fi n. Th e spot has the greatest concentration of melanophores of any pigmentation feature.
Th e fl ank in females can have up to 14 thin, dark, wavy and irregular vertical patches of pigment. Th ese patches may be interrupted in their vertical extent and are weakly expressed anteriorly. Th ey fade ventrally, ending above the lower edge of the caudal peduncle and above the anal fi n base, and are absent on the lower anterior fl ank. Th e patches are light and not as contrasting with the lighter interspaces as the bars found in males. Patches are thin, half to one third of the width of the interspaces. Very often the patches are broken up into spots and elongate blotches of various sizes, and a regular barred appearance is not usual. Th e spots and blotches are all smaller than the eye size by at least half. Material from Basrah, Iraq fi gured by Berg (1949;Fig. 5 herein) has the spots emphasised but material from Basrah (BM(NH) 1982.9.2:326-328) examined for this study has a more blotchy appearance and spots are not well-defi ned.  Etymology. Th e species is named for Mesopotamia (the land between the rivers) referring to the Tigris-Euphrates basin where the species is found. A proposed common name is Mesopotamian tooth-carp.
Distribution. Aphanius mesopotamicus is recorded from the southern Karkheh River basin of Iran and at Qarmat `Ali in Iraq at the northern part of Basrah on the Shatt al Arab, the confl uence of the Tigris and Euphrates rivers (Fig. 4). Th e Karkheh River drains to the Hawr-al-Azim marshes of the Tigris River basin on the Iran-Iraq border.
Conservation. Th e new species is known from only about 4 localities in southern Mesopotamia and has not been collected since 1978 in Iran and the early 1980s in Iraq. Specimens from Iran were easily caught using a dip-net. Several recent attempts post-2000 by the author and colleagues in both countries have failed to capture more specimens. It is not possible to assess whether this was due to chance or loss of the populations.
Habitat. The habitat of the new species is known only from field notes made at the time of capture in Iran on the Khuzestan plains. The two localities are a river and a canal branching from that river. The 25 m wide river had a water temperature of 22 °C at 1205 hours, pH 6.0, conductivity 1.0 milliSiemens, a mud bottom and the principal plant materials were rushes and reeds. The 30 m wide canal had a water temperature of 15 °C at 0930 hours, pH 6.0, conductivity 1.8 milliSiemens, a mud bottom and the principal plant material was filamentous green algae. Discussion. Aphanius species in Iran and Iraq show sexual dimorphism in pigmentation that can be used to identify and separate species. Generally, morphometric and meristic characters overlap and are only useful in multivariate space. Molecular techniques and otolith morphometry add confi rmatory evidence to colour patterns (Hrbek et al. 2006;Reichenbacher et al. 2007) but are not available for older material. Attempts to capture fresh material for molecular or otolith analyses of the new species by colleagues in Iran and Iraq have so far proved nugatory. Hrbek et al. (2006) give comparative tables for meristic and morphometric characters in species found in drainages adjacent to the new species (see Fig. 4).  (lower one CMNFI 1979-0360A andB, upper 1979-0364) Fish with wide, clear margins to the dorsal, anal and caudal fi ns in males is seen in material from Basrah fi gured by Berg (1949;Fig. 5 herein) although only in some printed versions of the fi gures (available only in photocopies) and this is not as evident in the fi gures here taken from the original drawings in St. Petersburg. Coad (1996) reviews the nomenclatural history of nominal Aphanius species in southern Iran.
While these small fi shes thrive in habitats marginal for other species, such as very small springs around salt lakes and saline habitats, they are less common in larger water bodies, at least in Iran. Introductions of exotics, particularly the mosquitofi sh Gambusia holbrooki, have placed the tooth-carps at a competitive disadvantage. Largescale aquaculture projects involving cyprinids and the malaria eradication programme involving mosquitofi sh have accidentally introduced many species outside their normal distribution in Iran. Th is may confound natural distribution patterns as smaller species are transported unawares along with the desired species. Historical collections are therefore important in describing and assessing the biodiversity of the Iranian ichthyofauna and even relatively recent collections may add to the known fauna as an understanding of diversity develops.  Berg (1949). Female (above), 30 mm, and male, 29 mm.