Scale morphology variability in cyprinid fishes and its significance in taxonomy using light and scanning electron microscopy: A case study of the genus Garra Hamilton, 1822 (Teleostei: Cyprinidae).

To evaluate scale morphological variability (shape, size, topological macro- and microstructures, ornamentation patterns) of cyprinid fishes, nine species of the genus Garra were selected and their scales from five different body regions were studied by using light and scanning electron microscopy. The scales of the examined species were thin with a central or antero-centrally positioned focus, with no cteni in the posterior part. In addition to these typical characteristics, some morphological variation was observed in the overall shape (irregular round, true oval, round-triangular, irregular pentagonal, hexagonal, irregular hexagonal, pentagonal, ovoid), and the focus shape. These variations were mainly dependent on the fish lengths and the flank region. Morphological analysis clustered the examined species into two distinct groups. Group I consisted of G. amirhosseini and G. gymnothorax, while Group II has three subgroups, which include G. persica and G. mondica (subgroup I), G. meymehensis, G. rossica, G. nudiventris, G. hormuzensis (subgroup II), and G. rufa (subgroup III). The grouping of the studied Garra species based on the current scale morphological characters and the molecular data was only consistent for G. rossica and G. nudiventris. In addition, in the phylogenetic tree, G. persica, G. mondica, G. amirhosseini, and G. hormuzensis formed a distinct clade. However, these species did not represent close relationships in the dendrogram obtained from the scale morphology. A possible explanation why the grouping of the studied Garra species based on their scale morphological characters does not match their phylogenetic relationships is that most of the scale morphological traits vary depending on the fish size and the location of the scales on the flank. Therefore, except for some traits, that is, central or antero-centrally positioned focus, having no cteni, a specific sectioned form so called "tetra-sectioned" type, the other examined variables are not useful enough to be used in the taxonomic study of the examined cyprinid fishes. Therefore, scale morphological characters should be used carefully for taxonomic purposes. RESEARCH HIGHLIGHTS: Shape, size, topological macro- and microstructures, and ornamentation patterns of nine species of the genus Garra were studied by using light and scanning electron microscopy. The scales were thin with a central or antero-centrally positioned focus, with no cteni in the posterior part. Morphological variation was observed in the overall shape (irregular round, true oval, round-triangular, irregular pentagonal, hexagonal, irregular hexagonal, pentagonal, and ovoid), and the focus shape. The grouping of Garra species based on the current scale morphological characters and the molecular data was only consistent for G. rossica and G. nudiventris.

Predicting climate heating impacts on riverine fish species diversity in a biodiversity hotspot region.

Co-occurring biodiversity and global heating crises are systemic threats to life on Earth as we know it, especially in relatively rare freshwater ecosystems, such as in Iran. Future changes in the spatial distribution and richness of 131 riverine fish species were investigated at 1481 sites in Iran under optimistic and pessimistic climate heating scenarios for the 2050s and 2080s. We used maximum entropy modeling to predict species' potential distributions by hydrologic unit (HU) occupancy under current and future climate conditions through the use of nine environmental predictor variables. The most important variable determining fish occupancy was HU location, followed by elevation, climate variables, and slope. Thirty-seven species were predicted to decrease their potential habitat occupancy in all future scenarios. The southern Caspian HU faces the highest future species reductions followed by the western Zagros and northwestern Iran. These results can be used by managers to plan conservational strategies to ease the dispersal of species, especially those that are at the greatest risk of extinction or invasion and that are in rivers fragmented by dams.

Evaluation of scale development and its regeneration potency in the desert killifish under laboratory conditions.

Scale development and its regeneration potency were evaluated in a desert killifish Aphaniops hormuzensis (family Aphaniidae) in laboratory conditions by using light and scanning electron microscopy. Scale development in A. hormuzensis took 156 days at room temperature. Four specific regions of scale formation were detected. The first scale development began 13 days post-hatching (dph) (total length [TL] = 8.5 mm) at the caudal peduncle region and is extended anteriorly 26 dph (TL = 13.6 mm) at the area below the dorsal fin. Scales began forming independently in the head region at 33 dph (TL = 21.7 mm), and in the abdominal region, began at 41 dph (TL = 25.8 mm). Additional points of scale origin were detected on the sides of the operculum or behind and below the eyes. Scale regeneration in the caudal peduncle started 6 days after removal (dar). In 16 dar, the microstructural features appeared and the growth circles, a wide and oblong focus (focus length = 0.6 ± 0.05 µm), and lepidonts were also formed. In 36 dar, the scale shape was gradually changed from circular to a polygon, and radii were distinguishable in the anterior field. The pattern of scale formation could be useful in enhancing the understanding of systematics and phylogeny, functional morphology, and habitat use. It could also be useful in helping to define the Larval/juvenile transition period.

Habitat and river riparian assessment in the Hyrcanian Forest Ecoregion in Iran: providing basic information for the river management and rehabilitation.

The Hyrcanian Forest holds broad leaf forest remnants dating back to the early Cenozoic Era, which once covered a vast area of the North Temperate Zone. Today, many rivers within this region have been altered by human activities and urgently need rehabilitation. In this regard, 35 wadeable rivers including 14 reference and impacted sites were investigated to determine how different human pressures altered riverine landscapes and habitats. Hence, five common human pressures (agriculture, urbanization, aquaculture, dams, aggregate mining) were identified, then the riverine landscape and habitat condition of each site were assessed. At each site, 17 aquatic, riparian, and terrestrial features, including abiotic and biotic substrate types, were investigated. The number and ratio of pressure-influenced channel features and substrate types differed from those in reference sites. Reference sites were dominated by microlithal, mesolithal, and macrolithal abiotic substrates and large wood, algae, and coarse particulate organic matter biotic substrates. Urbanized sites were most altered and dominated by single channels, steep unvegetated riprap banks, and algae substrate. The results provide valuable information for managers and decision-makers to restore riverine ecosystems considering the impaired parameters resulting from human pressures.

Otolith Morphology: A Hidden Tool in the Taxonomic Study of Goatfishes (Teleostei: Perciformes: Mullidae).

Goatfishes (Teleostei, Mullidae) are a group of mainly coastal fishes that form an important part of food chains, and also have commercial value. In the marine waters of Iran, they are found in the Persian Gulf and Oman Sea (Gulf of Oman). This study evaluated whether otolith morphology can be used to distinguish of species and genera, and also to interpret whether otoliths of the same species differ among two studied marine systems. To do this objective, the otolith morphology of ten species belonging to three genera were analyzed by SEM photography and shape analysis. Among the morphometric variables, relative rostrum length was found to be the most important otolith variable for discriminating Mulloidichthys (RRL = 32.29 ± 0.59) and Parupeneus (RRL = 37.39 ± 1.10), while rectangularity (REx) was the most important shape index for discriminating Mulloidichthys (REx = 0.99 ± 1.94) from Parupeneus (REx = 0.77 ± 1.21). By considering otolith morphology, Upeneus showed a better separation than the two other genera. The otoliths of Upeneus are diagnosed by short dorsal length (RDL = 69.35 ± 1.51), higher rostrum height (RRH = 53.63 ± 1.99), short rostrum (RRL = 31.12 ± 1.99), and antirostrum lengths (RanL = 12.38 ± 1.51). The most diverged phenotype within the genus Parupeneus was found for the otoliths of P. rubescens, and the most diverged phenotype within the genus Upeneus was found for the otoliths of U. sundaicus. The otoliths of the same species did not demonstrate large variation between the Persian Gulf and the Gulf of Oman. This study provides additional morphological evidence for the separation of goatfishes at the species and genus levels. We also underline that the slight observed differences between the otoliths of two marine systems are mainly caused by the ecological differences known between these two main systems.

Morphological and microstructural characteristics of scales in longnose goby Awaous jayakari (Teleostei: Gobiidae): Light and scanning electron microscopy approaches.

The scale morphology of a native goby, Awaous jayakari (Gobiidae) was studied using scanning electron microscopy and light microscopy. The morphological descriptions were based on the scale's type, shape, and features of the anterior, posterior, and lateral fields. Further characteristics of the focus, circuli, radii, lepidonts, and cteni, were investigated. Morphometric indices were calculated for some scales. Shape variability of scales was high in different regions. However, the majority of scales displayed a polygonal shape (hexagonal and pentagonal). Both ctenoid and cycloid scales were observed in the studied fishes. The ctenoid scale of A. jayakari was peripheral and characterized by the presence of one row of marginally located spines in two completed and uncompleted subtypes. The focus was positioned posteriorly or postero-centrally. The microscopic examinations revealed the presence of lepidonts of different sizes being very tiny, small, or prominent performing flat, blunt, pointed, short, or truncated shapes. The rostral margin of the scales was convex to moderately flattened and represented striate, scalloped, or waved types. Lateral fields were often flattened in all regions, while convex in the lateral fields of the scales of some individuals. The posterior field showed variations in different regions, for example, tapered and flattened ends. The anterior-posterior axis presented a laterally expanded or an elongated extension. The considerable morphological variation in the scales of various body regions makes it difficult to nominate a typical scale to be used in taxonomic studies. However, the key scales can be used for the comparison of different Awaous species.

Hidden morphological and structural characteristics in scales of mullid species (Teleostei: Mullidae) using light and scanning electron digital imaging.

The scale morphology of nine Mullidae taxa consisting of three genera and nine species from the Persian Gulf and the Gulf of Oman was described and compared using light and scanning electron microscopy from four different body regions. The general scale type in the studied mullid species was ctenoid except in the head region of Mulloidichthys vanicolensis and Parupeneus margaritatus, which had cycloid scales. The scales demonstrated a large focus with the central or centro-posterior position. The large variations of scale morphology were observed for the scales from different body regions of a single species. The shape of focus was in five types with the round type being the most common. In the scales of most examined species, there were 5-6 radii present in the anterior field. No radii exist in the lateral and posterior fields, and the radii orientation was parallel in all the studied species. The rostral margin of scales represented five types among the studied species; waved (M. vanicolensis), smooth in (P. rubescens), dentate (Upeneus doriae), scalloped (U. vittatus), and fluted (U. tragula). The lepidont shape varied among the species from blunt to flat, pointed, tiny, sharp, pointed, triangle, short, and long. The results also showed that the relative scale size has a desirable contribution to separate the examined genera. The scale morphological-based tree was largely consistent with the known systematics of the studied fishes. It was concluded that variation of scale characters has probably taxonomic and even phylogenetic information in both species and genus levels in the studied mullid fishes. However, variation of scale morphology between body regions, as shown in this study, suggests that scale characters should be used cautiously for taxonomic studies of these fishes.

Scanning electron microscopy and morphological analysis reveal size-dependent changes in the scale surface ornamentation of tooth-carp Aphaniops hormuzensis (Teleostei; Aphaniidae).

Aphanius hormuzensis is an endemic tooth-carp found in the Hormuzgan drainage in S-Iran. This study aimed to investigate the size-dependent alternations of scale surface ornamentation in this species by conducting scanning electron microscopy and morphological analysis. A total of 50 wild fish individuals were captured from Shur River, and were classified into five size classes based on the standard length; SC-I (SL = 10-20 mm), SC-II (SL = 21-30 mm), SC-III (SL = 41-50 mm), SC-IV (SL = 51-60 mm), and SC-V (SL = 61-70 mm), and their scales were removed from below the dorsal fin (key scale) and caudal peduncle regions. The results revealed a clear trend of scale structural development in A. hormuzensis. The scale of small-sized (TL < 30 mm) and large-sized fishes (TL > 30 mm) differed, respectively, in the following characters; the overall shape (often circular vs. polygonal), relative focus size (large, FL/SL = 440-610 µm vs. intermediate and small, FL/SL = 100-330 µm), types of radii (only primary vs. three types), relative radii length (short, RL/SL = 100-180 µm vs. long, RL/SL = 320-450 µm), lepidont (absent or undeveloped vs. present and developed), and the relative lepidont length (short, LL/SL = 0.83-0.90 µm vs. intermediate and long, LL/SL = 1.2-2.2 µm). These character alternations could explain certain developmental stages in this species. The size-dependent changes in the surface micro-ornamentations as shown in this study suggest that these characters should be used cautiously for taxonomic studies of the aphaniid fishes.

Digital light microscopy to characterize the scales of two goatfishes (Perciformes; Mullidae).

The normal and lateral line scales from above the head and four flank regions were investigated in two goatfishes by using light microscopy to evaluate the microscopic characteristics of scale surface ornamentation from different body parts of these fishes and to add new morphological data for their discrimination. The body scales were removed and digital images captured with a Dino-Lite digital camera connected to a Leica compound microscope. The presence of both transverse and longitudinal radii was a distinctive characteristic for the scales of studied goatfishes. The most distinctive features of the key scales discriminating the two goatfishes were the scale shape, the presence of irregular grooves in scale surface, the presence of transverse radii in the lateral fields, and the availability of lepidont at the anterior field. The lateral line scale ornamentations were almost similar in two species; however, the lateral line canal was branching in Parupeneus heptacanthus. Scale extension index indicated that in both species, the dimension of normal key scales tends to the right, while the dimension of lateral line scales tends to the left. This study accentuated that scales from different body regions may exhibit variation in surface ornamentations, that scale morphology could successfully be used to discriminate the examined goatfishes, and that the use of fish scale microscopy is an easy and relatively rapid method and does not require fish sacrifice. Since fish identification is essential for the conservation and management of species, the use of scale morphology to this purpose appears particularly promising.

Comparative ultrastructure and ornamentation characteristics of scales in gobiid species (Teleostei: Gobiidae) using the scanning electron microscope.

To study scale based phylogenetic affinity, the ultrastructure and ornamentation characteristics of body key scales were studied for 12 gobiid species from the Iranian coast of the Persian Gulf including Qeshm and Hormuz Islands and the Makran coast of the Oman Sea using scanning electron microscopy (SEM) technique. The scales were removed from below the first dorsal fin, cleaned in potassium hydroxide solution 1%, and were prepared for the SEM imaging. The presence of both ctenoid and cycloid scales in the studied gobiids was revealed. The focus of ctenoid scales was positioned posteriorly, while the focus of cycloid scales was positioned in the postero-central part of the scale. In all the studied species, radii were located only on the anterior part of the scale, and the primary radii were dominant. Also, there were no granules in the inter circular space, but bifurcation was observed in some circuli. In most species, the teeth-like structures called lepidonts were present on the crest of circuli, which functionally help to firmly attach the scales to the epithelium. The dendrogram of the between-groups-linkage method sorted the gobiid species into the two main groups of five distinct clusters: (a) Cryptocentroides arabicus and Cryptocentrus cyanotaenia (the Cryptocentrus-lineage); (b) Bathygobius meggitti and Bathygobius cocosensis (the Glossogobius-lineage); (c) Coryogalops adamsoni and Coryogalops tessellatus (the Gobius-lineage); (d) Acentrogobius dayi, Istigobius ornatus, Favonigobius reichei, Aulopareia ocellata, and Silhouettea ghazalae (the Gobiopsis-lineage). It seems that the dendrogram topology obtained based on the macro-and microscopic structures of scales, reveals phylogenetic lineages of gobies that have already been proposed for these taxa. Hence, the results of this study are largely consistent with the previous molecular studies on the gobiid fishes and implied that besides other data, the analysis of scale shape and scale-surface microstructures could be served to study the diversification of gobiid species.

Microanalysis of scale morphology in killifish, Aphaniops hormuzensis inhabiting ecologically diverse environments (Cyprinodontiformes; Aphaniidae).

Ecologically, Aphaniops hormuzensis populations occupying diverse environments in southern Iran and showed substantial morphological variation across its range. In this study, three different habitats were chosen and identified as group A (sulfur rich spring), group B (salty River), and group C (urban canal), and scale microstructures and scale shape was inspected among three groups. The SEM imaging indicated that lepidonts were more developed on the scale of larger (group C, SL > 30 mm) than younger fish (group A, SL < 30 mm). We tentatively concluded that lepidonts are formed during scale development so that in the earlier stages of fish development, scales probably do not have lepidont. Also, the size and shape of lepidonts vary between the populations, and their shape and orientation within a given species affected by the fish size rather than the local ecological conditions of habitats. The number of radii was relatively higher in group C (12.58 ± 0.66 in males and 13.00 ± 1.89 in females). Similar to what is mentioned before in the case of lepidont, the inter-population variation in the number of radii seems to be influenced by fish size. Group A (SL < 30 mm) had a relatively large focus diameter (0.14 ± 0.02 in males and 0.36 ± 0.44 in females). It is assumed that the focus size is large at the earlier stage of fish development, but later during the fish growth, and by increasing the scale size, the focus diameter is reduced. In conclusion and agreement with previous studies, scale surface morphology and microstructure could be employed to discriminate certain populations, while scale size and J-indices could not help in distinguishing the populations. It is also proposed that the characteristics of scale morphology in the population-level are influenced by the combination of genetic, and environmental factors, as well as fish development.

Adult neuronal regeneration in the telencephalon of the killifish Aphaniops hormuzensis.

The potential of central nervous system regeneration was evaluated for the first time in the injured brain of the old world killifish Aphaniops hormuzensis. The histomorphological organization in the regeneration procedure was evaluated using the hematoxylin and eosin (H&E) staining and the bromodeoxyuridine (BrdU) immunohistochemistry technique. The histological tissue sections were sampled daily for 10 days. Based on the H&E staining, a large gliosis reaction was detected along with vacuolization and telencephalon deformation on 1-day post-lesion (dpl). The vacuolated zone declined fast and the telencephalon hemisphere recovered on 3 dpl. The symptoms of injured telencephalon nervous tissue were resolved within 7 dpl in both genders. In the BrdU test of the control group, BrdU-labeled cells were observed in the ventricular zone (VZ), pallium (Pa), and lateral pallium (LPa). On 1 dpl, the BrdU+ cells accumulated in the VZ, Pa, and LPa (located near the injury area). From 3 dpl onwards, the BrdU+ cells were reduced in the telencephalic VZ, Pa, and LPa. Based on the BrdU+ results, the adult brain in A. hormuzensis possesses a remarkable capacity for neuronal regeneration. By taking into account the high neural regeneration potency of A. hormuzensis and its relatively short lifespan, it could be concluded that besides the currently known models, the members of aphaniid fishes could probably be valuable animals to study the regeneration phenomenon in the vertebrates.

Comparative microscopic examination of scales in 21 clupeid species from the Caspian Sea and the Indo-Pacific regions.

The clupeid fishes are large filter-feeding organisms and have diverse groups of trophic guilds and habitats. They are known for their special body scale, which is unique among the other teleost fishes. Here, we examined microscopic characteristics of scales in 21 clupeid species from four marine resources, including the Caspian Sea, the Persian Gulf and the Gulf of Oman (Indian Ocean) and South China Sea (Haian Islands and Shanwei, Pacific Ocean) to evaluate if the scale features could properly contribute to understanding the taxonomic relationships in these fishes. Typically, the studied scales were morphologically categorized into two types; circular (i.e., true circular, cordate, discoidal) and pentagonal. Also, it was found that the number and the orientation of radii and continuous striae, the presence of pores at the posterior field, overall shape, striations on the posterior field, and scale sizes could be used as suitable features to classify the clupeids in species and genus levels. The result of morphological analysis based on the scale characteristics was largely consistent with the phylogenetic relationships of the studied species. This highlighted that morphological characteristics of the clupeid scale could adequately contribute to the understanding of taxonomic relationships in this large group.

DNA barcoding and species delimitation of the Old World tooth-carps, family Aphaniidae Hoedeman, 1949 (Teleostei: Cyprinodontiformes).

The fishes, which have currently named Aphanius Nardo, 1827 are the relict of the ancient ichthyofauna of the Tethys Sea. For a long time since 1827, the genus name has been subjected to revision by several researchers using mainly morphological features. Until recently, no comprehensive single- or multi-locus DNA barcoding study has been conducted on whole members of the family Aphaniidae. In the present study, by applying four conceptually different molecular species delimitation methods, including one distance-based method, one network-based and two topology-based methods, we examined a single-locus DNA barcode library (COI) diversity for the 268 sequences within the family Aphaniidae from the Old World (57 sequences are new in the present study and 211 sequences were retrieved from NCBI database). The molecular analyses revealed a clearer picture of intra-family relationships and allowed us to clarify the generic names, and also describe a new genus for the family Aphaniidae. Results supported distinction of three major clades related to three genera within this family: i) the first clade includes the A. mento group which are placed in a new genus, Paraphanius gen. nov., found in the Orontes (= Asi) and Tigris-Euphrates River drainage, the Levant in coastal waters and the Dead Sea basin, western Jordan, and in southern Turkey in the Mediterranean basins as well as in central Turkey. This clade positioned at the base of the phylogenetic tree, (ii) the second clade contains the A. dispar-like brackish water tooth-carps which are transferred to the genus Aphaniops Hoedeman, 1951 (type species, Lebias dispar), distributed in the coastal waters around the Red Sea and the Persian Gulf basins; and (iii) the third clade, the genus Aphanius Nardo, 1827 (type species Aphanius nanus = A. fasciatus) contains all the inland and inland-related tooth-carps, which are mainly distributed in the inland waters in Turkey and Iran and also in the inland-related drainages around the Mediterranean basin.

Characterization of age-dependent variability in the flank scales of two scorpaeniformes fishes by applying light and scanning electron microscopy imaging.

The morphology of scales from four flank regions in two species of Scorpaeniforme fishes of the family Platycephalidae was studied by applying light and scanning electron microscopy, and the age-dependent variability of scale structures was discussed. The scales of four flank regions from three size classes in both species were ctenoid. The posterior margin of all the ctenoid scales was formed by two rows of cteni, while the three complete rows of cteni were not observed in the examined scales. The cteni of both rows were similar in morphology. Some scale characteristics showed alteration during the fish growth, including the shape of the anterior region of scale in Platycephalus indicus, the presence of lepidonts in Grammoplites suppositus, and the general shape of scale as well as the indices SCL.SCW and JSW.SL in both species. Also, the number of cteni in posterior margin of scales was increased during fish development, while their general morphology did not change significantly. The number of cteni in the scales of small and large fishes in G. suppositus was found to be obviously lower than P. indicus. By considering the function of lepidonts in improving the hydrodynamic efficiency of swimming, it can be assumed that G. suppositus is not probably very active in swimming as P. indicus. As a conclusion, modification in the ornamentations of the posterior region are subject to alteration during the growth of the fish. Besides its developmental changes, some scale characters in the adult forms have taxonomic significance, including the square-shaped scales in P. indicus vs. the oval-shaped scale in G. suppositus; a total of 26-31 radii in the anterior field in P. indicus vs. 11-12 radii in G. suppositus; the presence of many (54-58) cteni in the posterior part in P. indicus vs. a moderate (19-23) cteni in G. suppositus. These characters could be used as additional morphological data to be used for studying systematics and even phylogeny of the flathead fishes.

Paraschistura kermanensis, a new stone loach species from southeastern Iran (Teleostei: Nemacheilidae).

Paraschistura kermanensis from the endorheic Kerman-Naein basin in Iran is distinguished from its closest congeners (P. abdolii, P. delvarii, P. kessleri and P. naumanni) by lacking scales on the flanks anterior to the dorsal-fin origin, having scales on the caudal peduncle, and having the pelvic-fin origin situated anterior to or below the vertical through the dorsal-fin origin. It is also characterised by six fixed diagnostic nucleotide substitutions and a K2P nearest neighbour distance of 4% to P. abdolii in the mtDNA COI barcode region.

Histomicroscopy and normal anatomy of the adult killifish Aphanius hormuzensis (Teleostei; Aphaniidae) from the Persian Gulf coastal environment.

The histomicroscopy and normal anatomy of the major body organ systems were investigated in the adult killifish, Aphanius hormuzensis using histological examination, X-ray imaging, double staining, light microscopy and scanning electron microscopy (SEM). Based on the histomicroscopic observations, the kidney, liver and swim bladder in the studied species were comparable to other fish models. The anterior portion of the kidney is bulbous, while the posterior portion is narrow and elongated; the liver has a single lobe and the swim bladder is a single-chambered organ with no connection to the digestive tract (physoclistous). X-ray imaging and double staining examination showed 12 abdominal and 15 caudal vertebrae and a single hypural plate in the caudal skeleton. According to light microscopy, the scales were rounded to pentagonal in shape with three types of radii (primary, secondary and tertiary), and the urohyal bone was elongated. SEM microscopy showed a single row of tricuspid teeth on the upper and lower jaw, respectively, each tooth has two lateral cusps that are shorter than the middle one. The number of teeth was 17-18 in the upper jaw and 19-20 in the lower jaw. The saccular otoliths were rounded-trapezoid in shape with a moderately incised and V-shaped excisura. The members of killifishes are an important group for biologists because of their evolutionary properties, regeneration capacity and usefulness as biological control and also for the ecotoxicological assessment of environmental pollution. The outcomes of this study may provide a useful basis for future research on the genus Aphanius.

Molecular systematics and distribution review of the endemic cyprinid species, Persian chub, Acanthobrama persidis (Coad, 1981) in Southern Iran (Teleostei: Cyprinidae).

The Iranian Persian chub is an endemic species of the family Cyprinidae known only from few localities in drainages of Southern Iran. It was originally described in the genus Pseudophoxinus as (Pseudophoxinus persidis) and then Petroleuciscus (as Petroleuciscus persidis). In this study, we examined phylogenetic relationships of the Iranian Persian chub with other relatives in the family Cyprinidae based on the mitochondrial cytochrome b gene to estimate the phylogenetic (and taxonomic) position of the species. Our molecular phylogenies show that new fish sequences from the drainages in southern Iran are clustered with sequences of the genus Acanthobrama from GenBank while the sequences from two other genera (Pseudophoxinus and Petroleuciscus) are in distinct clade. Therefore, we conclude that the populations of Persian Chub in drainages of southern Iran (i.e., Kol, Kor, Maharlu and Persis) belong to the genus Acanthobrama and species Acanthobrama persidis. The predicted geographic distributions for the species showed a large area of suitable climate for A. persidis across south and west of Iran especially in the Kor River basin. Some other parts in the Persis and Tigris are also might have been suitable habitats for this cyprinid species showing possible dispersal route of Acanthobrama from Tigris to the Persis, Kor and Kol basins.

Two new species of the tooth-carp Aphanius (Teleostei: Cyprinodontidae) and the evolutionary history of the Iranian inland and inland-related Aphanius species .

Two new species of Aphanius are described from the Kol drainage in southern Iran (Aphanius darabensis n. sp.) and the endorheic Kavir Basin in northern Iran (A. kavirensis n. sp.), and compared with eight closely related species. Aphanius darabensis n. sp. is sister to A. shirini, from which it is distinguished by molecular characters (cytochrome b) and the combination of three morphological characters: 9-18 flank bars in males (vs. 7-10), females with irregular vertical patches of brown color on the flank (vs. prominent dark brown blotches of round or irregular shape), and symmetrically-shaped triangular to trapezoid otoliths with a rostrum distinctly longer than the antirostrum (vs. quadrangular to trapezoid otoliths with short and equally sized rostrum and antirostrum). Aphanius kavirensis n. sp. is closely related to a group containing A. sophiae, A. mesopotamicus and A. pluristriatus, from which it is distinguished by cytochrome b characters and the combination of three morphological characters: females with irregularly arranged large blotches of dark brown color on the flank, short pectoral fin in both sexes (13.4-18.1% SL in males, 11.2-18.3% SL in females), and asymmetrically shaped triangular to trapezoid otoliths with a pronounced predorsal region. Our tree based on the cytochrome b data demonstrates that the Iranian inland and inland-related Aphanius species (IIRAS) form a monophyletic clade with three subclades (A. vladykovi -, A. shirini -, A. sophiae subclades). The A. sophiae subclade, which is the most diverse of the three subclades, can be further divided into three lineages (A. isfahanensis -, A. farsicus -, A. sophiae lineages). The temporal diversification of the IIRAS clade is discussed and two evolutionary groups of Aphanius are depicted. Aphanius vladykovi, together with A. shirini, A. darabensis n. sp. and A. isfahanensis characterize the "old" evolutionary group. Their divergences may have happened 10-5 m.y. ago (Late Miocene-Early Pliocene). Aphanius farsicus, A. arakensis, A. sophiae, A. mesopotamicus, and A. pluristriatus, together with Aphanius kavirensis n. sp., represent the "young" evolutionary group, which developed in the Late Pleistocene (100,000-11,700 y. ago) and Early to Middle Holocene (c. 11,700-4,000 y. ago).

Scale surface microstructure and scale size in the tooth-carp genus Aphanius (Teleostei, Cyprinodontidae) from endorheic basins in Southwest Iran.

A substantial number of species within the tooth-carp Aphanius Nardo, 1827 (Cyprinodontidae, Teleostei) has been recorded from the endorheic drainage systems of Iran, and several isolated populations in these systems may deserve species status. Descriptions of these species and populations have been based mainly on morphological and molecular data; however, the characters related to the fish scales have not up to now been intensively studied and employed for the identification of the species belonging to this genus. The objective of this study is to test as to whether (i) scale surface morphology, (ii) scale surface microstructure, and (iii) scale size can be used to discriminate species and/or populations and, (iv) to discuss the possible causes of the observed differences. To achieve these objectives, scales of three species of the genus Aphanius from endorheic basins in SW Iran, viz. A. sophiae (nine populations from the Kor River Basin), A. farsicus (four populations from the Maharlu Lake Basin) and A. pluristriatus (a single population from the Mond River Basin) have been studied using SEM images, scale measurements, and uni- and multivariate statistics. It is opined that scale surface morphology and microstructure cannot help in distinguishing the species, but can be employed to discriminate certain populations of A. sophiae (those from Safashahr, Kharameh, Tashk, Gol). In addition, scale size and J-indices, respectively, represent a valuable tool for species separation, which corroborates earlier studies for the use of these indices in taxonomy. Major driving forces of the differentiation within A. sophiae probably include habitat fragmentation resulting from the geological history and local adaptations. Thus the differentiation results from a balance between both genetic and environmental effects.