Geographical differentiation of Aphanius dispar (Teleostei: Cyprinodontidae) from Southern Iran

The Arabian cyprinodontid Aphanius dispar (Rüppell, 1829) is known to show considerable morphological variation. It has remained unknown, however, whether this variation is a result of environmental differences or allopatric divergence owing to geographical isolation. In this study, 11 populations of A. dispar from three geographically separated basins were analysed, that is, the Makran Basin (I, one river system), the Hormuzgan Basin (II, five rivers and three hot springs) and the Helleh Basin (III, two hot springs) in southern Iran. Statistical analyses do not indicate significant differences between the fishes from river and hot spring habitats (T‐test, p < 0.05), which is also supported by the Canonical Discriminant Analysis (CDA). Nevertheless, morphometric and meristic characters of the fishes, as well as otolith morphology and morphometry, demonstrate that six phenotypic characters discriminate the A. dispar populations of the three basins, that is, (1) predorsal distance (Prdd.SL), (2) head length (HL.SL), (3) pelvic fin length (Lplf.SL), (4) number of pelvic fin rays, as well as relative length of both the (5) medial part and (6) rostrum of the otolith. In addition, these characters display a consistent pattern of variation, thus providing support for the assumption that the phenotypically different A. dispar populations are a result of geographical isolation and not related to environmental differences. It is likely that the geological history of the drainage systems caused isolation event(s) that may date back to the Pleistocene (1.8 million years before present). The high phenotypic differences might suggest that the A. dispar populations from the three studied basins represent separate subspecies or even species.     

Hybrids of Aphanius dispar and Aphanius mento (Cyprinodontidae: Pisces)

The results of reciprocal hybridization of Aphanius mento and Aphanius dispar are reported. The offspring were examined individually and compared with the parents. It was found that the female hybrids are closer to A. dispar , while the males are closer to A. mento.     

Aphanius vladykovi,a new species of tooth-carp from the Zagros Mountains of Iran (Osteichthyes: Cyprinodontidae)

Synopsis A new species of tooth-carp, Aphanius vladykovi, is described from the Zagros Mountains of Iran. The new species is uniquely characterised by a high count of lateral line scales and by different pigmentation patterns from its closest, putative relative A. sophiae. It also possesses several meristic and morphometric differences with topotypic A. sophiae. It became separated from a common ancestor with A. sophiae by orogenic events which led to the formation of the Zagros Mountains and the isolation of the upper reaches of the Karun River basin by the development of tangs, narrow passes through the mountains with high water flow and steep gradient which prevent gene flow between lowland and mountain populations of these small fishes.     

Length–weight relationships for four Aphanius species of Iran (Teleostei: Cyprinodontidae)

Length–weight parameters are presented for four endemic tooth‐carps of the genus Aphanius from Iran.     

Aphanius arakensis, a new species of tooth-carp (Actinopterygii, Cyprinodontidae) from the endorheic Namak Lake basin in Iran

A new species of tooth-carp, Aphanius arakensissp. n., is described from the Namak Lake basin in Iran. The new species is distinguished by the congeners distributed in Iran by the following combination of characters: 10-12 anal fin rays, 28-32 lateral line scales, 10-13 caudal peduncle scales, 8-10 gill rakers, 12-19, commonly 15-16, clearly defined flank bars in males, a more prominent pigmentation along the flank added by relatively big blotches in the middle and posterior flank segments in females, a short but high antirostrum of the otolith that has a wide excisura, and a ventral rim with some small, drop-like processes, and 19 molecular apomorphies (17 transitions, two transversions) in the cytochrome b gene. It was suggested based on the phylogenetic analysis that the new species is sister to Aphanius sophiae from the Kor River and that Aphanius farsicus from the Maharlu Lake basin is sister to Aphanius arakensis plus Aphanius sophiae. A noticeable feature of the Aphanius diversity in Iran is the conservatism of the external morphology as well as morphometric and meristic characters, while distinctive differences are present in genetic characters, otolith morphology, and male color pattern. Transformation of the latter was probably driven by sexual selection.     

Notes on the ecology of Aphanius dispar (Pisces, Cyprinodontidae) in the Sultanate of Oman

SUMMARY. Aphanius dispar was observed in the field and some simple laboratory studies were undertaken in Oman. A. dispar is almost totally ubiquitous in all bodies of fresh water where it occupies a wide range of habitats differing in stream flow, water chemistry, temperature and substrate quality. It often is found in association with one or both of two cyprinid fishes. Cyprinion and Garra. Aphanius is tolerant of wide ranges of salinity up to full marine water and has a wide temperature range. A. dispar resembles Cyprinodon species in a number of particulars, probably reflecting phylogenetic relationships and a common evolutionary response to desert conditions. It breeds throughout the year with a probable peak in the months of April to June.     

Morphological variation among populations of Aphanius fasciatus Nardo, 1827 (Teleostei, Cyprinodontidae) from the Mediterranean

The amount of osteological variation among 11 Italian killifish Aphanius fasciatus populations was examined by the univariate and multivariate analysis of 40 morphometric and meristic variables of the skull and vertebral column. Populations were sampled in three geographically distinct areas (the Adriatic, Sardinia and Sicily). The statistical analysis confirmed that several populations were well differentiated. In particular, discriminant analysis revealed a strong discriminating power of the morphometric variables. Morphometrics of the vertebrae, bony elements of the pharyngeal jaws, supraoccipital and parasphenoid were the most important in discriminating populations. The dendrogram obtained by UPGMA cluster analysis shows the separation of the south-eastern Sicilian populations, that of the Sardinian populations and that of the central-northern Sicilian plus Adriatic populations, as well as the isolation of the Sicilian population from Pantano Viruca and of the Sardinian populations from Pauli Figu from all the others. The significance of the observed differentiation pattern is discussed.     

Life‐history traits of Aphanius danfordii (Boulenger, 1890) (Pisces: Cyprinodontidae), endemic to Kızılırmak Basin (Turkey)

The life‐history traits of Aphanius danfordii in Hirfanl? Reservoir were studied on the basis of 2252 specimens caught between April 2008 and April 2009. Maximum age was determined as five years for both sexes. The overall sex ratio of males to females was 1 : 1.21; however, this ratio varied by age and season. Mean total length at age data derived from scale readings were used to estimate growth. The von Bertalanffy growth parameters were: L_∞ = 126.63 mm, K = ?0.09, t₀ = 2.35 for females; and L_∞ = 61.2 mm, K = ?0.19, t₀ = 2.76 for males. The gonadosomatic index (GSI) values indicated spawning to be from May to September. Absolute fecundity varied from a minimum of 143 eggs for age one to a maximum of 698 eggs for age five. Relationships between fecundity–length and fecundity–weight were described by the equations: F = 0.0002 TL^3.3222 and F = 36.032 W^1.0053, respectively. The equation of the relation between absolute fecundity and age was F = 25.372 t^1.2343.     

Effects of pesticide temephos on the gills of Aphanius dispar (Pisces: Cyprinodontidae)

The changes in the behavior of Aphanius dispar, a cyprinodont fish when exposed to different concentrations of temephos, an organophosphorus pesticide widely used to control mosquito larvae in aquatic habitats are noted. The histopathology of gills exposed to temephos is studied in detail using light microscopy (LM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The gill lesions were seen in all exposed concentrations of 1, 5, 10 and 25 ppm and the magnitude of the damage increased with the increase in concentrations. The most adverse effects of temephos are the destruction of cartilage and the large-scale cell death. Other effects included the degradation of chloride cells (CCs), desquamation, epithelial lifting, hypertrophy and lamellar fusion. The histological changes of microridges did not follow a consistent pattern in exposed concentrations. However, lamellar curling and collapsing was common in all exposed fish.     

Phylogenetic analysis of Aphanius from the endorheic Kor River Basin in the Zagros Mountains,South‐western Iran (Teleostei: Cyprinodontiformes: Cyprinodontidae)

Morphologically similar populations of Aphanius that are currently considered as A. sophiae inhabit the endorheic Kor River Basin in the Zagros Mountains. Using genetic analysis based on mtDNA (cytochrome b), combined with examination of morphology (morphometry, meristics, otoliths), we discovered that what is thought to be A. sophiae is actually two distinct species, one of which is described as A. shirini sp. n. The males of the new species can be distinguished from those of all other Iranian inland Aphanius species by having only 7–10 clearly defined white flank bars, which is the lowest number of flank bars among the Iranian inland Aphanius species. Both males and females differ from all other Iranian inland Aphanius species by having a significantly longer caudal peduncle and a smaller dorsal fin depth. Based on the PhyML and Bayesian likelihood trees, A. shirini is sister to A. vladykovi from the Karoun Basin in the Zagros Mountains. Our results indicate that an ancient exorheic Kor River Basin existed in the Late Miocene and Pliocene. The close phylogenetic relationship between A. shirini and A. vladykovi suggests that the pre‐Pliocene drainage in the ancient Kor River Basin was directed to the north‐west (to the Karoun Basin), and not to the south‐east as in the present‐day Kor Basin. Both A. shirini and A. vladykovi represent the highest altitude records for Aphanius. We conclude that the splits of A. shirini and A. vladykovi can be linked to tectonic events in the Middle to Late Miocene, which created the highest altitudes (>3000 m) in the Zagros Mountains, and led to isolation of populations. The present‐day endorheic Kor Basin is known to have formed in the Late Pleistocene or Early Holocene, and the ‘young’ age of A. sophiae is clearly related to this history. Our results contribute to elucidate the link between geological history and the present‐day species diversity in the tectonically still active Zagros Mountains of Iran.     

A new and unique species of the genus Aphanius Nardo, 1827 (Teleostei: Cyprinodontidae) from Southern Iran: A case of regressive evolution

A primarily vicariance-based speciation has been suggested for the killifish genus Aphanius Nardo, 1827, but ecological factors are likely to have promoted the speciation processes in addition. Here, we report on the discovery of a unique Aphanius species from Southern Iran and show that also regressive evolution has shaped the present-day diversity of Aphanius. The species is characterized by complete absence of scales and reduction in the biomineralization of hard structures, particularly of the caudal skeleton and jaw teeth. Based on mt-DNA sequences, morphometric and meristic data, osteology, jaw teeth and otoliths, it is described as Aphanius furcatus sp. n. The new species is sympatric with A. dispar (Rüppell, 1829) in salty rivers and hot sulphuric springs in the Hormuzgan Basin (Southern Iran), and is sister taxon to this species plus A. ginaonis Holly, 1929. Based on geological data we estimate that the divergence between the lineages of A. furcatus and A. dispar is about 12–14 million years old. We conclude that the reductive phenomena observed in A. furcatus have evolved as an evolutionary response to the extreme habitat conditions in order to save energy (because storage of Ca²⁺ is not necessary), and to transport oxygen efficiently. The results confirm that regressive evolution is an important factor in speciation and occurs independently in separate lineages.     

Embryonic and early development of the Zagros tooth‐carp,Aphanius vladykovi (Actinopterygii: Cyprinodontidae)

The embryonic and early larval development of laboratory reared Zagros tooth‐carp, Aphanius vladykovi Coad, 1988, are described and illustrated. Development and embryogenesis start with the external fertilization of sticky, transparent and spherical telolecithal/macrolecithal eggs with a mean diameter of 1.61± 0.12 mm and it continues with meroblastic/radial cleavage, blastulation/blastula formation, epibolic cell migration during gastrulation and organogenesis resulting in a newly hatched larvae of 5.23 ± 0.09 mm in length with attached yolk sac at about 164 hr (at 24 ± 1°C) after fertilization.     

The endangered cyprinodont <Emphasis Type="Italic">Aphanius ginaonis</Emphasis> (Holly, 1929) from southern Iran is a valid species: evidence from otolith morphology

Aphanius Nardo, 1827 (Actinopterygii, Cyprinodontidae) is a widely distributed genus in the Mediterranean and Persian Gulf area and includes several endangered species. The otolith morphology in Aphanius is known to represent a valuable tool for the taxonomy, and is also indicative for the genetic diversity of a particular population. The present study focuses on the otoliths of the endangered A. ginaonis (Holly, 1929), which is endemic to the Geno hot spring in southern Iran. The taxonomic status of A. ginaonis has repeatedly been questioned, and some scholars have argued that it merely represents a morphological variation of the widespread A. dispar. We present a comparison of the otolith morphology of A. ginaonis (52 specimens) with that of A. dispar (Rüppell, 1828) from the Mehran River Basin (southern Iran) (17 specimens) and an A. dispar population from the Persian Gulf coast of the United Arab Emirates (32 specimens). Our data obtained from SEM pictures, otolith morphometry and statistical analyses suggest that A. ginaonis represents a valid species. In A. ginaonis individuals with a standard length exceeding 23 mm, the otolith variables length–height and rostrum length represent useful complementary diagnostic characters discriminating this species from other Aphanius species. Besides ontogenetic variation, we found extremely high otolith form variability in A. ginaonis, including some otoliths with a morphology distinctly deviating from the basic morphology type. We hypothesize that these variations may be a result of the artificial introduction of A. dispar into the Geno hot spring during the last years and subsequent hybridisation.     

Isolation and characterization of eight polymorphic microsatellite markers in Aphanius fasciatus (Teleostei: Cyprinodontidae)

The first set of eight polymorphic microsatellites markers was successfully optimized from a partial genomic library enriched for an AC motif of the killifish Aphanius fasciatus Nardo, 1827 (Teleostei, Cyprinodontidae), a brackish‐water fish widely distributed along the coasts of the Mediterranean Sea. The developed loci proved to be polymorphic, displaying from two to six alleles per locus with expected heterozygosity ranging from 0.277 to 0.752. All loci were under Hardy–Weinberg equilibrium, except Af8 that showed significant heterozygotes deficiency, and there was no evidence of linkage associations between any pair of loci. Markers reported here will be potentially useful in monitoring of genetic population structure in this species.     

Contrbtion to the biology of Zagros tooth-carp, <Emphasis Type="Italic">Aphanius vladykovi</Emphasis> (Cyprinodontidae) in central Iran

We studied some aspects of the biology of the Zagros tooth-carp, Aphanius vladykovi, an endemic and poorly known species from Chahar-Mahall-va-Bakhtiari province in central Iran, by regular monthly collections and direct observation in aquaria over a full year. We collected individuals from Modar-Dokhtar spring of Gandoman region; we preserved some in formalin and transferred some alive to aquaria. The stomach contents consisted mostly of freshwater crustaceans, suggesting a carnivorous habit. The eggs had an average diameter of 1mm and the average absolute and relative fecundity was 415 and 110, respectively. The gonadosomatic ratio and ovary condition suggested that the reproductive season of the species was between late March and June with a peak in early April. The species is euryhaline and eurythermal and prefers neutral to basic waters. It is usually found in well-oxygenated waters, but is tolerant of hypoxia as well.