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The Arabian goby, Cryptocentroides arabicus (Gobiidae: Gobiinae), is a significant species in marine and brackish water ecosystems. However, limited information is available about the reproductive biology and the early life history of this species. This study aimed to understand the embryonic and pre-larval development of C. arabicus under controlled laboratory conditions using light microscopy. Ten fish pairs were placed in five 70-L glass aquaria, and environmental parameters were carefully monitored. After 4 months, spawning began, with each event yielding between 700 and 1500 eggs, totaling 10 spawning events. The elliptical-shaped eggs, measuring 3.9 ± 0.1 mm in length and 1.6 mm in maximum width, hatched after 7 days and 4 h at a water temperature of 28°C. This process resulted in the identification of eight distinct larval developmental stages. Parental care by both the male and female was observed during the incubation period. Documenting the morphological changes during incubation contributes to a better understanding of the reproductive behaviour and early life history of C. arabicus. This is essential for the conservation management of marine and brackish water environments., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Climate change is one of the most significant challenges worldwide in the Anthropocene, and it is predicted to importantly affect biological diversity, especially in freshwaters. Freshwater fishes are facing considerable global threats, particularly in eco-sensitive semi-arid to arid areas such as the Arabian Peninsula, which is considered a highly stressed region in the Middle East. Endemic species are believed to display a narrow range of traits, with rarity reflecting adaptation to specific environmental regimes, and they are thus highly sensitive to environmental disturbances. This study is the first attempt to map the occurrence of endemic freshwater fish species and predict the impact of climate change on their spatial range in the semi-arid area of the Arabian Peninsula using Species Distribution Modeling (SDM). We compared the present and future (2041-2060 and 2061-2080) climate niche for the species under various climatic scenarios. All global circulation models (GCMs) performed well in predicting the species' climatic niche (AUC ranging between 0.72 and 0.92). For certain species (Cyprinion acinaces, Garra buettikeri, Carasobarbus exulatus, Arabibarbus arabicus, and Cyprinion mhalense), variables associated with precipitation were more important than those related to temperature, while for others (Carasobarbus apoensis, G. sahilia, G tibanica, and Aphaniops kruppi), temperature-related variables were most important. Precipitation in the coldest quarter and in the driest quarter was the most sensitive variable for the predictions. The species showed distinct responses to climate change; seven were predicted to lose their climatically suitable habitats (losers) and are thus threatened and highly vulnerable to the effects of climate change, while two species were predicted to expand their range (winners). Regular monitoring of fish in the Arabian Peninsula is recommended to conserve endemic species and their ecosystems., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Hamid Reza Esmaeili reports a relationship with Shiraz University that includes: employment. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Microplastics (MPs) are concerning emerging pollutants. Here, MPs in four edible aquatic species of different trophic levels (between ∼2 and 4), including fish species Esox lucius (Esocidae: Esocinae); Cyprinus carpio (Cyprinidae: Cyprininae); and Luciobarbus caspius (Cyprinidae: Barbinae); and the swan mussel Anodonta cygnea (Unionidae), were assessed in the Anzali freshwater ecosystem. It is a listed wetland in the Montreux record. MPs were extracted from gastrointestinal tracts (GI), gills, muscles, and skin. All the studied fish and mussels (n = 33) had MPs. MP fibres, fragments and sheets were detected in every GI examined, however, fibres were the only type of MPs in skins, muscles and gills and were the most abundant MP. The MPs found in the fish and mussels were mainly made of nylon (35% of the total MPs), polypropylene-low density polyethylene (30%), and polycarbonate (25%). The average numbers of MPs found in every fish specimen, expressed per wet body mass, had a moderate negative correlation with the condition factor (K) (MP/g - K: Pearson correlation r = -0.413, p = 0.049), and there was no significant relation with the growth factor (b) (r = -0.376; p = 0.068). Importantly, Luciobarbus caspius (with trophic level 2.7-2.8) bioaccumulated MPs and presented a strong correlation between their MP contamination and age (r = 0.916 p < 0.05). Greater gill mass (or related factors) played an important role in the accumulation of MPs, and there was a strong correlation between these factors for Esox lucius and Cyprinus carpio (r = 0.876; r = 0.846; p < 0.05 respectively). The highest MP/g gills (1.91 ± 2.65) were in the filter feeder Anodonta cygnea inhabiting the benthic zone. Esox lucius (piscivorous, trophic level 4.1) was the most contaminated species overall (a total of 83 MPs in 8 individuals, with 0.92 MP/g fish), and their gills where MPs mainly accumulated. Cyprinus carpio was the most contaminated specimen (MPs in specimens), while the number of MPs per mass unit increased with the trophic level. Their feeding and ecological behavior in the aquatic habitat affected the level of accumulation. This work includes evidence of translocation of MPs within the aquatic organisms., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Hamid Reza Esmaeili reports a relationship with Shiraz University that includes: funding grants. Maryam Saemi reports a relationship with Ministry of Science Research and Technology of the Islamic Republic of Iran that includes: funding grants. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

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., (© 2024 Wiley Periodicals LLC.)

This study investigated the morphological characteristics of scales in six Cyprinion species, using light and scanning electron microscopy focusing on key features such as scale type, key scales, lateral line scales, radius/radii, rostral margin, focus, circuli, lepidonts, tubercles, and scale indices. The research analyzed the scales using ultramicroscopy and light microscopy imaging, categorizing them based on size classes and body regions. The morphological variations in scale characteristics were examined across different species, regions, and size classes. Notable findings included the tetra-sectioned form of scales, representing a unique characteristic of the Cyprinion genus. Morphological changes in scale features were observed with fish growth, particularly in the overall shape, focus shape, and size. Quantitative analysis revealed variations in average relative scale length and width among different species, regions, and size classes. The study utilized canonical discriminant analysis for multivariate assessment, classifying the species into distinct groups based on morphometric indices. The findings contribute to the understanding of scale morphology in Cyprinion species and exploring morphological variation between the examined species., Competing Interests: Conflict of Interest: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Microscopy Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Freshwater fishes are facing considerable threats in the Arabian Peninsula which is considered as a highly stressed region in the Middle East. It is predicted that northern Oman is likely to face decreasing rainfall and increasing temperature in coming decades. In this study, we focused on an endemic cyprinid fish Cyprinion muscatense , as a model to investigate impacts of climate change on the mountain fishes inhibiting in this arid region. This species is expected to be strongly affected by climate change because of its limited distribution range in a montane area surrounded by lowlands and sea, limiting the species in shift to other areas. We used an ensemble approach by considering two regressions-based species distribution modeling (SDM) algorithms: generalized linear models (GLM), and generalized additive models (GAM) to model the species habitat suitability and predict the impacts of climate change on the species habitat suitability. Based on the distribution models, the montane area located in northeastern Oman was identified as the most suitable habitat for this species. Our results indicate that, even under the minimum greenhouse gas emissions scenario (RCP 2.6), climate change will produce a high reduction in its potential future habitats. According to the results of percent contribution, elevation and annual minimum temperature were the most important variables in predicting the species suitable habitats. Results also showed that only a small percentage of suitable habitats for the species within boundaries of protected areas. Therefore, the impact of climate change on the species appears particularly alarming. Although our study was restricted to a single cyprinid freshwater species, decreases in potential habitats are likely predicted for other cyprinid fish species restricted to the mountains of this region, suggesting severe consideration is needed for aquatic systems in future conservation planning, especially for endemic freshwater fishes., Competing Interests: The authors declare no competing interests., (© 2024 The Author(s). Ecology and Evolution published by John Wiley & Sons Ltd.)

This paper presents the conclusions of a comparative analysis of six osteological features: the Structure of the vertebral column, the morphology of the predorsal bones, the vertebral column regionalization, the pterygiophore interdigitation with neural spines of dorsal fin, the pterygiophores interdigitation of with the haemal spines of the anal fin, and the intermuscular bones (IMB) and hypomerals (HM) of 12 clupeid species of the families Alosidae, Dorosomatidae, Dussumieridae and Ehiravidae. Conceivable taxonomically beneficial osteological features are nominated and utilized to discrete the clupeid species explored. Formulae for the structure of the vertebral column, the dorsal- and anal-fin pterygiophores' interdigitation with the neural and haemal spines of the vertebrae are established. These morphological descriptive traits disclose a morphotype that may be related to the mode of swimming of the species searched. The morphological study of the vertebral column of the species in question permits the division of this bony structure into six morphologically different regions. This regionalization is more intricate than the classical division in abdominal and caudal parts only., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Members of the genus Cyprinion (Cypriniformes: Cyprinidae) are found in the Indus River basin west to the Arabian Peninsula and the Tigris-Euphrates River drainages (Persian Gulf basin). The taxonomic status of Cyprinion including Cyprinion muscatense is poorly understood when compared to other cyprinid genera. C. muscatense has been considered as a member of the Cyprinion watsoni-microphthalmum group and a valid species endemic to the Arabian Peninsula. Here, we redescribe C. muscatense based on an integrative morphological and molecular approach and freshly sampled material from several localities in the Oman Mountains ecoregion. The results showed that C. muscatense is distinguished from the other Cyprinion species in the Arabian Peninsula by having a short, thin, and slightly serrated last unbranched dorsal fin ray; the lower number of circumpeduncular scales; lateral line scales; and also scales between the lateral line and the dorsal-fin origin. Subterminal mouth, presence of one pair of small barbels at the mouth corner, 3-4 unbranched and 9½-10½ dorsal-fin branched rays, 12-14 pectoral-fin rays, 7-8 pelvic-fin rays, 2-3 unbranched and 6½-7½ branched anal-fin rays, and 37-40 lateral line scales are other morphological characteristics of C. muscatense. C. muscatense is also well distinguished by molecular characters among its congeners. The first molecular phylogenetic analysis of the genus, covering all currently recognized Cyprinion species except for C. watsoni, is also presented. C. muscatense is resolved as the sister species to another endemic fish of the Arabian Peninsula Cyprinion mhalense, with a Kimura-2-Parameter model distance of 5.3%., (© 2024 Fisheries Society of the British Isles.)

This checklist aims to update the list of the inland fish fauna of Iran including newly described species and also clarify the status of some taxa including some gobies and catfishes which were ignored in the checklist provided by Eagderi et al. (2022). The checklist is arranged by classes, orders, families, and species. In total, 300 species, belonging to 110 genera, 38 families, 23 orders, and three classes were recognized from Iranian basins, with the presence of 11 reported species that need confirmation by specimens. Additional notes about the taxonomy of several taxa are provided in the discussion section.

The current status of the freshwater fishes of Iraq is revised, and an updated checklist is presented. The confirmed freshwater fishes of Iraq comprise 98 species belonging to 16 orders, 28 families, and 56 genera. Among these, 21 species (21.4%) are alien, and three species (3.0%) are considered endemic to Iraq. The orders with the largest numbers of species in the ichthyofauna of Iraq are Cypriniformes (57 species), followed by Siluriformes (12 species), Mugiliformes and Cyprinodontiformes (six species in each), Acanthuriformes and Cichliformes (three species in each), Centrarchiformes and Gobiiformes (two species in each), and the others represent only one species. At the family level, the Cyprinidae have the greatest number of species (28; 28.3% of the total species), followed by Nemacheilidae (16 species), Leuciscidae (eight species), Mugilidae (six species), Sisoridae (five species), and Xenocyprididae (four species in each). A total of 20 species that have been previously reported from Iraq have been excluded from the checklist. According to IUCN Red List criteria, among 77 naturally distributed species (alien species not included), 10 species (13.0%) are categorized as threatened extinctions, with three (3.9%) as CR, one (1.3%) as EN, and six (7.8%) as VU. A total of 38 taxa were assessed (49.4%) as LC, 27 species were not assigned NE (35.1%), and two species (2.0%) were classified as DD, i.e., with insufficient knowledge.

The current status of the freshwater fishes of Syria is revised, and an updated checklist is presented. The confirmed freshwater fishes of Syria comprise 108 species belonging to 15 orders, 25 families, and 51 genera. Among these, 11 species (10.2%) are alien, and six species (5.6%) are considered endemic to Syria. The orders with the largest numbers of species in the ichthyofauna of Syria are Cypriniformes (68 species), followed by Siluriformes and (nine species), Cichliformes (eight species), Mugiliformes (seven species), Cyprinodontiformes (six species), and others represent one species in each. At the family level, Cyprinidae has the greatest number of species (30 species; 27.8% of the total species), followed by Leuciscidae (21 species), Nemacheilidae (11 species), Cichlidae (eight species), and Mugilidae (seven species). According to IUCN Red List criteria, among 97 naturally distributed species (alien species not included), Tristramella sacra extinct (EX) and 24 species (26.5%) are categorized as threatened extinctions, CR, EN, and VU (eight species in each). A total of 17 species previously reported from Syria have been excluded from the checklist, either in the present study or in previous studies.

The Indo-West Pacific Glossogobius giuris(Hamilton, 1822) species complex has four spatially circumscribed independent lineages, partially taxonomically resolved. A sample of gobies from the G. giurisspecies complex was recently collected from the Makran River System, south-eastern Iran, which drains into the northern Oman Sea. The taxonomic status of thispopulation was clarified using a molecular and morphological framework. Molecular and morphological data both revealed that the examined sample from the Makran River System is conspecific with G. giurisB which is widely distributed in the coastal habitats and basins of the Indian Ocean. In addition, consensus from different molecular species delimitations, K2P genetic distance, and tree topologies confirmed the four lineages of the G. giuris species complex as distinct taxonomic entities, hereby highlighting the necessity of an integrative morphological and molecular approach to complete the clarification of taxonomic diversity within this group. Glossogobius giuris species complex taxonomy is discussed and solution recommended.

The presence and effects of nanoplastics (NPs; <1 μm) in the aquatic environment are a growing concern. In this study, a model tooth-carp fish, Aphaniops hormuzensis, has been exposed to different concentrations of fluorescent polystyrene nanoplastics (PS-NP) in its diet (up to 5 mg kg -1 ) over periods of 28 d and the particle accumulation in different tissues determined. Accumulation was observed in both digestive and non-digestive organs, with concentrations greater in the gut, liver and gill (up to 400 μg kg -1 dw) than in the skin and muscle (<180 μg kg -1 dw), but no dependency on exposure time or dose was evident. The presence of the organic contaminant, triclosan (TCS), in the diet and at concentrations up to 0.5 μg kg -1 did not affect PS-NP uptake by A. hormuzensis, while TCS accumulation in the whole body increased with time (up to 10 μg kg -1 ) and, likewise, appeared to be unaffected by the presence of PS-NPs. These observations suggest that the two contaminants do not interact with each other or that any interactions have no impact on accumulation. The results of this study add to the growing body of evidence that NPs can be translocated by aquatic organisms after ingestion, and reveal that, for the species and conditions employed, nanoplastics are accumulated more readily than a widely used organic chemical., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The Arabian Peninsula comprises the seven countries of Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, the United Arab Emirates, and Yemen (including the Socotra archipelago), covering an area of more than 3 million km). Although arid habitats cover most parts of the Arabian Peninsula, the region has several freshwater systems and comprises all or parts of four freshwater ecoregions basins that support a variety of inland aquatics including fishes. The current checklist provides all fish species in inland waters of the Arabian Peninsula including all recognized and named taxa, documenting recent changes and controversies in nomenclature, records, taxonomic status, occurrence, synonyms, common English name, range distribution, and conservation status based on several field surveys throughout the area and available articles. The confirmed inland ichthyodiversity of the Arabian Peninsula comprise 48 species belonging to 25 genera, 14 families, nine orders, and a class. Among these, 10 species (20.8%) are alien, and 21 species (52.3%) are considered endemic to the Arabian Peninsula. Favonigobius reichei is a new record for inland waters of the Arabian Peninsula. The most diverse order is Cypriniformes (19 species, 39.6%), followed by Cyprinodontiformes and Gobiiformes (eight species, 16.7% in each), Cichliformes (four species, 8.33%), Mugiliformes (three species, 6.25%), Anguilliformes and Siluriformes (two species, 4.17% in each), and Centrarchiformes and Gonorynchiformes (one species, 4.2% each). Saudi Arabia and Oman with 23 species (47.9% each) rank first in fish diversity (both native and exotic), followed by Yemen (15 species, 31.25%), UAE (seven species, 14.58%), Bahrain (two species, 4.17%), and Qatar and Kuwait (one species, 2.1% each). Of 21 endemic species of the Arabian Peninsula, six, six, and four species are restricted to the territories of Oman, Saudi Arabia and Yemen, respectively. No endemic fish have been reported from Bahrain, Kuwait, Qatar, and the United Arab Emirates. The list also includes two subterranean species belonging to the genus Garra. The provided data will be necessary to take action for effective conservation management strategies and policies.

This study investigated the concentration of PAHs in 19 water samples, 34 sediment samples and 22 fish samples of Anzali Wetland, located in north of Iran. The average concentration of ∑PAHs in the wetland sediment was 89.19 μg/kg (8.28-806.64) and 78.31 ng/L (5.14-253.37) in the wetland water. Also, the average concentration of ∑PAHS in the muscle of the investigated fish in the wetland was 23 μg/kg (56.1 to 7.6). The source apportionment of PAHs in water and sediment considering isomeric ratios and statistical methods reveals the predominance of petrogenic origin of the compounds in water and pyrogenic origin in sediment. Overall, the level of contamination in fish is relatively low to moderate, considering ∑PAHs. The findings present clear evidence of low to moderate level of contamination in the wetland, the PAHs contamination however could cross their ecological thresholds in future unless control measures are taken to protect the wetland., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2023. Published by Elsevier Ltd. All rights reserved.)

Coastal wetlands are sensitive ecosystems that give habitat to large number of species. The extent of the impact of microplastic pollution in the aquatic system and humans is not known. In this study, the occurrence of microplastics (MPs) was assessed in 7 aquatic species from the Anzali Wetland (40 fish and 15 shrimp specimens), a listed wetland on the Montreux record. Specifically, the tissues analyzed were gastrointestinal (GI) tract, gills, skin, and muscles. The total frequency of MPs (all detected MPs in the GI tract, gill and skin samples) varied from 5.2 ± 4.2 MPs/specimen for Cobitis saniae to 20.8 ± 6.7 MPs/specimen for Abramis brama. Among all tissues studied, the GI tract of the Chelon saliens, a herbivorous demersal species, had the greatest level of MPs (13.6 ± 10 MPs/specimen). Significant differences (p < 0.05) were found between the abundance of MPs in different species, tissues, living domains and feeding habit types. The findings support that fish may uptake MPs through adherence in gills (respiration) in addition to ingestion. White/transparent and black/grey polyamide (PA) fibers were the most common type of MP which may be originated from municipal wastewater and intensive fishing activities. About 34% of the MPs were in the range of 250 μm-500 μm, and those >100 μm were not detected in muscles from the study fish. All species had unhealthy weight according to the Fulton's condition index (K). Positive relationships existed between biometric properties (total length and weight) of species and the total frequency of uptaken MPs, pointing to detrimental impact of MPs in the wetland., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2023. Published by Elsevier Ltd. All rights reserved.)

Otoliths (ear stones) of the inner ears of teleost fishes, which develop independently from the skeleton and are functionally associated with hearing and the sense of equilibrium, have significantly contributed to contemporary understanding of teleost fish systematics and evolutionary diversity. The sagittal otolith is of particular interest, since it often possesses distinctive morphological features that differ significantly among species, and have been shown to be species- and genus-specific, making it an informative taxonomic tool for ichthyologists. The otolith morphology of the Caspian Sea gobiids has not been thoroughly studied yet, with data available for only a few species. The aim of the present paper is to examine the qualitative and quantitative taxonomic and phylogenetic information in the sagittal otoliths of these species. A total of 118 otoliths representing 30 gobiid species (including 53.5% of the Caspian gobiofauna) in three gobiid lineages (i.e., Gobius, Pomatoschistus, and Acanthogobius) and 11 genera (i.e., all Ponto-Caspian gobiid genera except Babka) were analysed at taxonomic levels using an integrated descriptive and morphometric approach. The results indicated high taxonomic efficiency of otolith morphology and morphometry at taxonomic levels for the Ponto-Caspian gobiids. Our qualitative and quantitative otolith data also (i) support the monophyly of neogobiin gobies, (ii) along with other morphological and ecological data, offer a new perspective on the systematics of Neogobius bathybius, (iii) suggest the reassignment of Hyrcanogobius bergi to the genus Knipowitschia, and (iv) question the phylogenetic integrity of the four phenotypic groups previously defined in the tadpole-goby genus Benthophilus; however, more studies are needed to complete these evaluations and confirm our otolith study findings., Competing Interests: The authors have declared that no competing interests exist., (Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.)

Microplastic (MP) contamination is a persistent and ubiquitous threat to aquatic ecosystems. This study quantifies MP ingestion by fish inhabiting the Anzali Wetland (Iran), a hotspot of biodiversity. Growth parameters have been monitored in endemic demersal fish (Caspian spined loach, Sabanejewia caspia), and invasive benthopelagic species (Prussian carp, Carassius gibelio) in the wetland and compared with their internal content of MPs. MPs were extracted from the gastrointestinal (GI) tracts following digestion of the samples in alkaline medium and observation of the extracts with microscopy (Scanning Electron Microscopy equipped with an Energy-Dispersive X-ray microanalyzer (SEM-EDS) and confocal Raman microscopy). A total of 84.6 % of the study fish (n = 26) were contaminated with MPs. Fibres were the only type of MPs found in the GI tracts, and these were mainly dark blue and made of polycarbonate and nylon in both investigated species. The mean numbers of MPs in the GI tracts of the carp and the loach were 3.6 and 3.7 respectively. MPs had smooth surfaces in most cases although some presented brittle, fragmented, and uneven surfaces and signs of degradation. The growth rates of Carassius gibelio and Sabanejewia caspia, measured with the b value (growth factor), were 2.91 and 2.15 respectively. Carassius gibelio can play a significant role in the transport of MPs to other aquatic organisms inhabiting the Anzali wetland, and hence can cause potential harm to them. Carassius gibelio MP contamination was more pronounced with increasing gut mass in older specimens. Due to the presence of MPs and in fish that can be consumed, there could be a trophic transfer to humans. Regarding Sabanejewia caspia, although not statistically significant, their uptake of MPs tends to increase in older specimens with smaller size and body weight. This can imply that MP pollution causes inappropriate conditions and results in negative growth. The findings of this work provide new insights into MP contamination in the Anzali wetland, specifically in endemic fish. These results will be important in conservation and management programs., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Garra is the most species-rich genus of freshwater fishes in the Arabian Peninsula, including Oman, which has eight recognized, species restricted mainly to the Hajar and Dhofar mountains. Garra species from the Dhofar region in Oman are reviewed based on integrated morphological and molecular (COI) data of newly collected fishes from the type localities of G. sindhae and G. smartae, and a new population from Wadi Laggashalyon. No diagnostic character was found to distinguish the two species and the Laggashalyon population as distinct taxa. Garra dunsirei, another species endemic to a sinkhole at Tawi Attair, a very difficult area to access at a depth of about 211 m, was examined here based on the GenBank data and the diagnostic characters given in the original descriptions of the studied Garra species. In addition, the phylogenetic tree placed the sequenced Omani Garra fishes into nine groups with K2P sequence divergence of 0.8% (G. smartae and G. smartae&#95;Laggasaylon); 1.2% (G. smartae and G. sindhae), and 14.5% (G. Shamal and G. dunsirei) in their COI barcode region. A molecular species delimitation approach using PTP, also detected one entity for Garra species from the Dhofar region (G. dunsirei, G. sindhae and the both populations of G. smartae), which is consistent with our morphological data. Therefore, based on absence of diagnostic characters, low genetic distance, and molecular species delimitation approach, we treat G. sindhae and G. smartae as junior synonyms of G. dunsirei.

The complex architecture of fish scale has been investigated for several decades to show an existing link between scale morphology/microstructure and systematic/evolutionary relationships of fishes. In the present study, the surface architecture structure associated with the scales of a hill stream cyprinid fish Garra shamal restricted to the Hajar Mountains of the Arabian Peninsula was examined by optical light and scanning electron microscopy; (i) to describe the whole morphology, architectural design and hidden microstructures of scales in an endemic fish of the Arabian Peninsula, G. shamal, (ii) to investigate the phenotypic plasticity of scales in six selected regions of the fish body, (iii) to show an ontogenetic pattern of scale morphology in different size classes, and (iv) to study morphometric parameters for scales, and determine the most valuable indices for differentiating the scales of different body regions and the different size groups of studied species. For this purpose, scales were removed from six body regions of three size classes. The scale of G. shamal, as an ossified platelet and hard structure covering the outer part of fish in different body parts and size groups, demonstrated numerous hidden morphological and structural characteristics, and sculptural design, for example, type, shape, and size in general term, and circuli (thickness, arrangement, and relative spacing of circuli around the focus), radii (number, shape, its origin from focus), lepidonts (the texture, shape, size, orientation, and type of its attachment), and granules (shape, size, number, and configurations) in a specific term, that can contribute efficiently in fish identification and classification at the genus and species levels. Position of focus, presence of radii in all four fields of scales (anterior, posterior, and laterals) and thus tetra-sectioned type, presence of specific tubercle arrangement on the posterior region, and some scale indices can be used as a taxonomic tool in Garra identification. Moreover, scales in G. shamal demonstrated plasticity in different fish size classes, and the origin of scales on the fish body, revealing a kind of ontogenetic variation, and the importance of key scales (scales below the dorsal fin) in the lepidological studies. The quantitative and qualitative traits described here based on the optical light microscopy and electron scanning microscopy can be implemented along with other morphological and molecular characteristics to have a better taxonomic resolution of the genus Garra. RESEARCH HIGHLIGHTS: The optical light microscopy (LM) and scanning electron microscopy (SEM) techniques enhanced our knowledge of scale morphology in a cyprinid fish restricted to the Arabian Peninsula. The scale of G. shamal, in different body parts and size groups, demonstrated numerous hidden morphological and structural characteristics, and sculptural design that can contribute efficiently in fish identification and classification at the genus and species levels. Tetra-sectioned cycloid type, position of focus, presence of specific tubercle arrangement on the posterior region, and some scale indices can be used as a taxonomic tool for identification of the genus Garra. The scales showed plasticity in different fish size classes, and the origin of scales on the fish body, revealing a kind of ontogenetic variation., (© 2022 Wiley Periodicals LLC.)

An evidence-based annotated checklist of gobiid species (Teleostei: Gobiidae) inhabiting the South Caspian Sea and its catchment area (i.e., the South Caspian Sea sub-basin) is compiled. The South Caspian Sea sub-basin gobiofauna currently comprises 38 confirmed species in 11 genera (i.e., 88.4% of the Caspian gobiofauna); the most diverse genus is Benthophilus (16 species, 42.1%), followed by Ponticola (seven species, 18.4%), and Neogobius (four species, 10.5%). Ten species (26.3%) are endemic to the South Caspian Sea sub-basin, another 21 species (55.3%) are endemic in the Caspian Sea basin as a whole, six (15.8%) are native to the Ponto-Caspian region, and one species (2.6%) is exotic. According to the current IUCN Red List, 24 species (64.9%) are listed as being of "Least Concern", eight species (21.6%) are "Data Deficient", and five species (13.5%) as "Not Evaluated". Similar numbers of species are confirmed to inhabit the South Caspian Sea sub-basin waters of the three countries that border it: Iran harbors 25 species (nine genera), Azerbaijan has 28 species (10 genera), and Turkmenistan has 26 species (10 genera). The greatest known diversity of Benthophilus in South Caspian waters occurs in Azerbaijan and Turkmenistan (11 species each), whereas Iranian waters harbor seven species. In comparison, Iran, with six out of eight species (75%), has the greatest diversity of Ponticola known from the Caspian Sea basin. Species richness and endemism of the Caspian Sea gobiid-fauna varies considerably with latitude: the North, Middle and South sub-basins respectively harbor 21, 31, and 37 native species, of which 0, 3, and 10 species are endemic in that sub-basin alone. The high species diversity and endemism of Gobiidae in the South Caspian Sea sub-basin may have resulted from: (i) greater ecological diversity compared to the northern Caspian Sea marine areas (e.g., water depths) that may have led to differential niche adaptation and adaptive radiation in the Benthophilus-Anatirostrum species flock, (ii) lower historical extinction rate compared to Caspian higher latitudes, which had greater exposure to the Pleistocene's extreme climatic changes, (iii) geological history of freshwater habitats in the South Caspian Sea sub-basin that set the speciation and evolutionary stage for the genus Ponticola during these Pleistocene climatic oscillations, (iv) presently less limiting conditions compared to the North Caspian Sea, i.e., higher present winter minimum of water temperature and higher salinity, and (v) Iranian freshwater abundance, variability and habitat diversity. Contemporary gobiid diversity and endemism in the Caspian Sea basin suggests two higher-priority conservation areas: (i) freshwater habitats of the South Caspian Sea region in Iran and Azerbaijan, and (ii) shallow coastal and deep waters of the South and Middle Caspian Sea sub-basins. An identification key is provided for the updated gobiid species from the South Caspian Sea sub-basin.

Freshwater habitats of the Caucasus biodiversity hotspot represent a center of endemism for the gobiid genus Ponticola Iljin, 1927. Hitherto, large-scale molecular studies, owing to restricted taxon and geographical sampling, have failed to give an elaborate picture of diversity and evolutionary history of these species. Here, to contribute to filling this gap, we assessed taxonomic diversity, phylogeography and evolutionary history for the south Caspian populations of Ponticola presently classified as P. iranicus and P. patimari , using an integrative taxonomic approach comprising an entire geographic range sampling, and analyses of mitochondrial DNA haplotypes, the head lateral line system, otolith shape, and meristic and morphometric variation. All freshwater samples of the P. syrman group belong to a monophyletic clade with two main subclades: a small subclade confined to the upper Sefidroud sub-basin including the type locality of P. iranicus and a large subclade with three geographically constrained haplogroups (Hg1, Hg2, and Hg3), comprising the rest of the distribution. Hg1 showed an eastern distribution including the type locality of P. patimari , while Hg2 and Hg3 are sister groups with central and western-central distributions, respectively. The freshwater clade diverged from P. syrman during the Tyurkyanian low stand (~150 m b.s.l. lasting ~0.1 Myr), while the divergence of P. iranicus and P. patimari and radiations within P. patimari took place during the Bakunian high stand (up to 50 m a.s.l. lasting ~378-480 kya). Species delimitation analyses indicated two distinct species, corresponding to each main subclade. Although the otolith shape and lateral line analyses did not reflect with phylogeographic pattern, PCA and DFA plots of meristic and morphometric data showed a clear separation of the two major subclades corresponding to P. iranicus and P. patimari , suggesting the presence of significant morphological variation meriting formal taxonomic recognition. Overall, our findings (i) reveal the presence of two freshwater endemic species in the P. syrman group , and pending further investigation, hypothesize the presence of a third cryptic species; (ii) revise and document a narrow distributional range and low diversity for P. iranicus , in contrast to a wider distributional range and high diversity for P. patimari ; (iii) suggest that the climatic oscillations of the Pleistocene were associated with the cladogenesis within the P. syrman group ; and (iv) allowed for the recognition of conservation units and proposition of management measures., Competing Interests: We declare no conflict of interest., (© 2022 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

Oxyurichthys omanensis sp. nov. is described as a new gobiid species from a mudflat/estuary habitat in northern Oman. The new species is diagnosed among all currently recognised congeners by the following combination of character states: elongate tentacle on dorsoposterior surface of the eye; nape with well-developed membranous crest; nape scaled to above anterior half of opercle along sides with naked median along membranous crest, scales never reaching to above preopercle; opercle and pectoral base naked; scales ctenoid laterally on trunk posterior to base of second dorsal fin 3rd element; lateral scale rows 5158, usually 5156; transverse forward scale rows 2329, usually 2428; transverse rearward scale rows 1416, usually 1415; upper lip usually constricted at premaxillary symphysis; infraorbital transverse papillae row 2 reaching eye margin dorsally and markedly short of longitudinal row d ventrally; additional short transverse papillae rows between rows 2 and 3i present; dark saddle present over caudal peduncle; snout length 34.945.4% HL; second dorsal-fin longest ray 1.11.6 head depth; pelvic fin always reaching or passing anal-fin origin. The K2P genetic distances (%) in the mtDNA COI barcode region between O. omanensis and the other Oxyurichthys species were all high (11.230.6%) with the K2P nearest neighbor distance of 11.2% to O. cornutus and O. ophthalmonema.

Ponticola hircaniaensis sp. nov. is described as a new gobiid species from the Kaboudval Stream, southern Caspian Sea basin. The new species is diagnosed among Caspian Sea basin Ponticola species by the following combination of characters: second dorsal-fin branched rays 1416, anal-fin branched rays 1012, scales in lateral series 5259; lower jaw slightly, if at all, prognathous; head and body yellowish brown showing a reticulate brown pattern on a yellow background, first dorsal fin with a marginal bright orangish-yellow band and a dark anterior spot, upper part of pectoral-fin base with a distinct dark brown stripe; length of third spine in first dorsal fin 13.418.3 % of standard length (SL), second dorsal-fin spine length 11.113.8 % SL, caudal peduncle length and depth 16.420.1 % and 11.112.8 % SL, respectively, head depth at nape 70.981.0 % of head length (HL), and at eye 52.566.0 % HL; sagittal otolith dorsal rim with a broad concavity in the middle, dorsal depression absent or indistinct, sulcus length/sulcus height and sulcus height/otolith height ratios 1.471.82 and 0.340.40, respectively. It is also characterised by a K2P nearest neighbour distance of 5% to P. kessleri in the mtDNA COI barcode region. Mitochondrial and nuclear DNA analyses suggested extensive hybridization between P. hircaniaensis sp. nov. and P. gorlap at Kaboudval, providing evidence for the first record of hybridization in the Ponto-Caspian gobiids. Based on narrow geographic range isolated above the Zarrin Gol Dam (< 2 km2), extensive hybridization with P. gorlap, and other threats, the new species should be considered Critically Endangered.

Oman, a country in Southwest Asia, situated on the southeastern quarter of the Arabian Peninsula presents a high level of biological diversity especially marine elements. Although arid habitats cover most parts of Oman (82%), the region has several freshwater systems that are vital for the survival of people as well as for different groups of animals and plants. Research works on Oman biodiversity including terrestrial and marine, have been steadily increasing over the last few decades, but freshwater ecosystems have not been well investigated. Oman comprises parts of three freshwater ecoregions including the Oman Mountains, Southwestern Arabian Coast, and Arabian Interior having xeric freshwaters and endorheic (closed) basins which support a variety of inland fishes. The current checklist provides for each species of inland waters of Oman all recognized and named taxa, documenting recent changes and controversies in nomenclature, its records, taxonomic status, synonyms, etymology, common English name, short description, range expansion, and detailed distribution map based on several field surveys throughout the country. We also provide native, endemic, and introduced species. The diversity of inland fishes of Oman included in this annotated checklist consists of 23 recognized species in 15 genera, 10 families, seven orders, and a class. Also, for the first time, we report and confirm the presence of four species in the inland waters of Oman. The most diverse order is Cypriniformes (nine species, 39.13%), followed by Gobiiformes (six species, 26.09%), Cyprinodontiformes (three species, 13.04%), Cichliformes (two species, 8.69%), and Centrarchiformes, Gonorynchiformes and Mugiliformes (one species, 4.35% each). 21 native species (91.3%) in nine families and two exotic species (8.7%) in two families are listed here. Out of 21 native species, eight species (16.8%) in two families are endemic elements that are restricted to the Oman territory only. Identification of all recognized species was confirmed by DNA barcoding (mitochondrial COI). Oman Mountains Ecoregion (OME), Southwestern Arabian Coast Ecoregion (SACE), and Arabian Interior Ecoregion (AIE) harbor 15, 12, and one species, respectively. The provided data will be necessary for increasing the fish knowledge, the development of competent and pragmatic management plans and effective conservation policies.

Glossogobius giuris was originally described as Gobius giuris from the Ganges River, India. However, based on the uncertainty of its type locality and its apparent widespread distribution, a comprehensive study is being carried out to define the correct taxonomic status of this taxon. The South African population of the Glossogobius from St. Lucia Lake, KwaZulu-Natal was described as Glossogobius tenuiformis by Fowler in 1934. It has usually been considered as Glossogobius giuris but Hoese and Hammer indicated that it was a distinct species (2021: 83). Here, based on morphological characters and a molecular data set, we redescribe Glossogobius tenuiformis and assign the Oman populations of Glossogobius to this species. Glossogobius tenuiformis is distinguished from G. giuris by the absence or very short (and often only a few papillae long) sensory papilla line 6; presence of single rows of the sensory papillae in each cheek line, 1216 pre-dorsal scale counts, and 1+1+911, usually 1+1+10, gill rakers on outer face of first arch. Glossogobius tenuiformis is also distinguished by molecular characters. Glossogobius tenuiformis shows 16% genetic distance with other members of this species complex, that includes G. laticeps from Vietnam, Bangladesh and China, G. giuris from South Africa and India and giuris C from India, Myanmar, Nepal, Bangladesh and Vietnam, and the highest genetic distance (24%) with G. circumspectus.

Mystus cyrusi, new species, is described from the Kol River drainage which flows to the Straits of Hormuz in southern Iran. It is distinguished from its closest relative, Mystus pelusius from the Tigris-Euphrates River system by a combination of characters: The maxillary barbel short, not reaching to beyond pelvic fin (vs. extends as far as anal fin in some female M. pelusius), shorter adipose fin (30.837.4% SL) and with a steeper sloping at its origin vs. longer (37.645.6% SL) and with a more gently sloping in M. pelusius), greater head depth (16.6421.9% SL vs. 12.616.59% SL in M. pelusius), greater caudal-peduncle depth (10.312.5% SL vs. 8.710.5% SL in M. pelusius) and fewer total gill rakers (1214, mode 12) vs. (1417 in M. pelusius). Mystus cyrusi is also well distinguished by molecular characters. Genetically, M. cyrusi shows the lowest genetic distance with M. pelusius (4.6%), and then with M. singaringan (11.6%), M. wolffii (13.1%), and M. bleekeri (13.4%) among the 21 studied species in their mtDNA sequences. Mystus cyrusi shows the highest genetic distance with M. montanus (26.5%).

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., (© 2021 Wiley Periodicals LLC.)

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., (© 2021 Wiley Periodicals LLC.)

Recognizing and defining a species has been a controversial concern for a long time. To define the variation and the limitation between different species, especially closely related taxa in a complex species group, several concepts have been proposed which may lead to different taxonomic decisions. When a taxonomist studies a specific taxon, she/he should adopt a species concept and provide a species limitation to define the studied taxa. Garra population from the Kol River drainage, Persian Gulf basin has already been considered as Garra sp., based on molecular data, and to date no taxonomic decision has been made to provide a specific name for it. The Kol population presents several morphological characters that distinguish it from congeners: fully scaled breast; 78 branched dorsal-fin rays; caudal fin with 1617 branched rays and well-developed mental disc with free lateral and posterior margins. It is also distinguished from all other congeners in the Garra rufa group in Iran, by having two fixed, diagnostic nucleotide substitutions in the mtDNA COI barcode region. Furthermore, the Kol population demonstrates some distinct osteological characteristics in comparison to its closest species G. mondica. Based on the integrative molecular phylogenetic and species delimitation analyses, and morphological, osteological and distribution range data presented here, we think that the Kol River population merits formal description and can be considered as a distinct taxonomic unit (species).

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 (RE x ) was the most important shape index for discriminating Mulloidichthys (RE x = 0.99 ± 1.94) from Parupeneus (RE x = 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.

This study assesses the frequency, distribution, characteristics, and chemical composition of microplastics (MPs) in the gut of highly consumed fish species, namely leaping mullet (Chelon saliens), common carp (Cyprinus carpioi), and Caspian kutum (Rutilus caspicus), in the southern Caspian Sea biome. Fibers are found to be the only shape of MPs. Black MPs and polystyrene, polypropylene, and polyethylene terephthalate polymers are dominant. MP frequency is highest in leaping mullet's gut, while kutum specimens exhibited the lowest MP frequency, reflecting that leaping mullet is a neritic species and thus highly exposed to MP influx in shallow coastal water, while the other species are benthopelagic. The estimated condition index reflected a significant difference between the species, implying that MPs may pose adverse health impacts on leaping mullet and common carp, with no undesirable effect on Caspian kutum. No significant relationship exists between biological parameters and the MP frequency in the fish gut., (Copyright © 2021. Published by Elsevier Ltd.)

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., (© 2020 Wiley Periodicals LLC.)

A new gobiid species, Benthophilus persicus sp. nov., is described from the southern Caspian Sea, Iran. The new species is diagnosed by the following character states: dermal fold on cheek well-developed, large, rectangular; chin barbel 1/32/3 of eye diameter; maximum body width 15.122.9% of standard length; mouth width, 36.355.8% of head length; second dorsal fin I+78; origin of anal fin in front of vertical through origin of second dorsal fin; dermal tubercles present on body, clearly larger than granules, with two posterior rows of spinules forming an acute angle, always less than right angle; dorsal row of tubercles complete, 2229; ventral row of tubercles 2225; ventrolateral row of tubercles absent; tubercles not present on temporal and occipital head regions; granules not present on flanks; transversal suborbital row 6i below posterior end of row b; anterior interorbital transversal row pa with one or two papillae and anterior interorbital transversal papilla row pp with two or three papillae; body with 2022 transversal ltm rows starting anteriorly behind pectoral axilla and alternating anteriorly with three longitudinal llm rows.

Oxynoemacheilus marunensis, new species, is described from the Marun, a tributary of the Jarrahi River, which flows just east of the Tigris River to the Persian Gulf. It belongs to a group of species (O. argyrogramma, O. euphraticus, O. hanae, O. karunensis, and O. kurdistanicus) having two bold, black, round, or comma-shaped black spots on the caudal-fin base. It is most similar to a newly described species from the Persian Gulf basin, O. karunensis, but distinguished from O. karunensis by having a longer distance between pelvic and anal-fin origins [22.3-23.8 vs. 19.5-22.3 (% SL)] and a K2P distance of 6% based on COI barcode region sequences.

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., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

A new bitterling from the Rhodeus amarus group is described based on morphological and molecular data. Rhodeus caspius sp. nov. from the Caspian Sea, Urmia Lake and the upper Tigris River drainages in Iran, is distinguished from its closest congeners (R. amarus and R. colchicus) by having short post-dorsal distance and caudal peduncle length and long head length. It is also characterized by one fixed diagnostic nucleotide substitutions and a K2P nearest neighbor distance of 1% to R. amarus and R. colchicus in the mtDNA COI barcode region.

Rapid adaptation to global change can counter vulnerability of species to population declines and extinction. Theoretically, under such circumstances both genetic variation and phenotypic plasticity can maintain population fitness, but empirical support for this is currently limited. Here, we aim to characterize the role of environmental and genetic diversity, and their prior evolutionary history (via haplogroup profiles) in shaping patterns of life history traits during biological invasion. Data were derived from both genetic and life history traits including a morphological analysis of 29 native and invasive populations of topmouth gudgeon Pseudorasbora parva coupled with climatic variables from each location. General additive models were constructed to explain distribution of somatic growth rate (SGR) data across native and invasive ranges, with model selection performed using Akaike's information criteria. Genetic and environmental drivers that structured the life history of populations in their native range were less influential in their invasive populations. For some vertebrates at least, fitness-related trait shifts do not seem to be dependent on the level of genetic diversity or haplogroup makeup of the initial introduced propagule, nor of the availability of local environmental conditions being similar to those experienced in their native range. As long as local conditions are not beyond the species physiological threshold, its local establishment and invasive potential are likely to be determined by local drivers, such as density-dependent effects linked to resource availability or to local biotic resistance., Competing Interests: There is no conflict of interest. We declare that none of the authors listed on the manuscript are employed by a government agency that has a primary function other than research and/or education., (© 2020 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

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., Competing Interests: The authors have declared that no competing interests exist.

Silhouettea ghazalae sp. nov. is described from Qeshm Island, Persian Gulf. Silhouettea ghazalae sp. nov. is distinguished from congeners by having: small mental fold present on chin, head length 31.4-32.4% of standard length, head width 24.5% of standard length, second dorsal fin I/11, anal fin I/13, breast with large cycloid scales, predorsal area naked, suborbital row b anteriorly beginning below anterior edge of pupil, posteriorly ending below pore β, suborbital row c anteriorly extending more than row b and posteriorly extending less than row b, suborbital row cp oblique with four papillae, body with four ill-defined midlateral blotches and the fifth a triangular mark on the caudal fin base, no clearly defined pale saddles on back, and the first dorsal fin pigmented with dots and with dark blotch present anteriorly. A key to Silhouettea species is provided. A dataset including novel and publicly available mtDNA COI sequences of 12 species from the Persian Gulf and Oman Sea gobies belonging to eight genera have been assembled in order to provide a reference dataset for DNA barcoding studies. The new species is further characterised by a minimum K2P distance of 21% to its closest relatives in our dataset, Cabillus tongarevae in the mtDNA COI barcode region.

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.

Recent studies on the analysis of the evolutionary relationships between the various taxa of the teleost fishes are based on the evaluation of the efficacy of different approaches, verifying the taxonomical congruence between the hypotheses inferred from molecular data and those from morphological data. The first objective of this study was to investigate the macro- and microscopic characterization of the body key scales for the sixteen Aphanius species, and to discuss their taxonomic significance. In addition, to reveal the phylogenetic origins of particular adaptations and to identify a possible cases of convergent evolution in scales of Aphanius species, we used a phylogenetic character mapping procedure that uses an independent data source, namely molecular data that is presumed to be functionally independent of the scale traits. Comparison of the resulted phylogenetic trees and scale data dendrogram implied that neither scale shape/scale surface morphology, nor scale surface microstructure can be used for the species identification and inferring phylogenetic relationships in the genus Aphanius. This conclusion confirms previous studies, indicating that the scale shape and ornamentations varies with habitat, age and size of the fish. We also concluded that the polygonal state in the scales of Aphanius species was a primitive shared character state., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

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., (© 2018 Wiley Periodicals, Inc.)

Genetic structure of an endemic tooth-carp fish, Aphanius farsicus from four different water bodies in the Maharlu Lake basin was investigated by applying five microsatellite markers. All of the five examined microsatellite loci showed polymor-phism pattern. A total of four alleles were detected at five microsatellite loci, with an average of 2.8 to 3.5 alleles per locus. Average values of observed and expected heterozygosity were 0.95±0.09 and 0.64±0.02 respectively. None of the tests of linkage disequilibrium were significant between each pair of loci and no deviation from Hardy-Weinberg equilibrium were detected to test for heterozygote deficiency within populations. The Nei's genetic distance values ranged between 0.03 - 0.13. Analysis of pairwise genetic differentiation between each pair of the populations revealed that fixation index ( F ST ) values ranged from 0.013 to 0.039 and R ST ranged from 0.005 to 0.065. High genetic diversity observed within the populations (99%) and low diversity (1%) among them indicating probably high level of gene flow among the studied populations of Fars tooth-carp at the present time or in the past. Regarding low genetic differentiation among the studied populations and results of population assignment test, two hypotheses are suggested and supporting evidence for each hypothesis are provided., Competing Interests: The authors declare that they have no competing interest.

The validity of C. keyvani and C. faridpaki is assessed based on morphological and molecular (COI) data from fishes collected from the type localities of both species. No diagnostic character was found to distinguish both species. Therefore, we treat C. keyvani as a junior synonym of C. faridpaki.

Iranocichla persa sp. n. is described from the Shur, Hasanlangi and Minab River drainages flowing into the Persian Gulf at the Strait of Hormuz in southern Iran. It is distinguished from Iranocichla hormuzensis , from the Mehran River drainage, by nuptial males having a bright orange breast and lower part of the head (vs. black), a poorly developed or invisible (vs. distinctive) " Tilapia -mark" in the dorsal fin and very clear white spots making almost wavy bars or stripes on the caudal fin (vs. without or with very few white spots). Mitochondrial DNA sequence characters suggest that both Iranocichla species are closely related but form two distinct clades, diagnosable by several fixed mutations in ND2, D-loop and partially by COI sequences. Populations from Kol River drainage, which is situated in-between the Mehran and the Shur River drainages, are more similar to Iranocichla hormuzensis in terms of their male nuptial coloration but to Iranocichla persa sp. n. in their mitochondrial sequence characters. Their status requires further investigation.

Squalius namak, new species, from the endorheic Lake Namak and Kavir basins in Iran, is distinguished from the species of the genus Squalius in the Persian Gulf and the southern Caspian Sea basins by having a wide and thick symphysial knob on the lower jaw, a convex posterior anal-fin margin, a bold, dark-grey or brown, roundish or crescent-shaped blotch at the posterior tip of each flank scale and orange caudal-, anal- and pelvic-fin rays in life. Squalius namak is also characterized by four fixed, diagnostic nucleotide substitutions in the mtDNA COI barcode region.

Capoeta damascina was earlier considered by many authors as one of the most common freshwater fish species found throughout the Levant, Mesopotamia, Turkey, and Iran. However, owing to a high variation in morphological characters among and within its various populations, 17 nominal species were described, several of which were regarded as valid by subsequent revising authors. Capoeta damascina proved to be a complex of closely related species, which had been poorly studied. The current study aims at defining C. damascina and the C. damascina species complex. It investigates phylogenetic relationships among the various members of the C. damascina complex, based on mitochondrial and nuclear DNA sequences. Phylogenetic relationships were projected against paleogeographical events to interpret the geographic distribution of the taxa under consideration in relation to the area's geological history. Samples were obtained from throughout the geographic range and were subjected to genetic analyses, using two molecular markers targeting the mitochondrial cytochrome oxidase I (n = 103) and the two adjacent divergence regions (D1-D2) of the nuclear 28S rRNA genes (n = 65). Six closely related species were recognized within the C. damascina complex, constituting two main lineages: A western lineage represented by C. caelestis, C. damascina, and C. umbla and an eastern lineage represented by C. buhsei, C. coadi, and C. saadii. The results indicate that speciation of these taxa is rather a recent event. Dispersal occurred during the Pleistocene, resulting in present-day distribution patterns. A coherent picture of the phylogenetic relationships and evolutionary history of the C. damascina species complex is drawn, explaining the current patterns of distribution as a result of paleogeographic events and ecological adaptations.

Traditionally, Capoeta populations from the southern Caspian Sea basin have been considered as Capoeta capoeta gracilis . Study on the phylogenetic relationship of Capoeta species using mitochondrial cytochrome b gene sequences show that Capoeta population from the southern Caspian Sea basin is distinct species and receive well support (posterior probability of 100%). Based on the tree topologies obtained from Bayesian and Maximum Likelihood methods, three main groups for the studied Capoeta were detected: Clade I) Capoeta trutta group (the Mesopotamian Capoeta group) including closely related taxa (e.g. trutta , turani , barroisi ) characterized by having numerous irregular black spots on the dorsal half of the body. This clade was the sister group to all other Capoeta species and its separation occurred very early in evolution possess, so we considered it as O ld Evolutionary Group. Clade II) comprises highly diversified and widespread group, Capoeta damascina complex group (small scale capoeta group), the Anatolian-Iranian group (e.g. banarescui , buhsei , damascina , saadii ), characterized by small scales and plain body (absence of irregular black spots on the dorsal half of the body, except in some juveniles) with significantly later speciation event so called Young Evolutionary Group. Clade III) Capoeta capoeta complex group (large scale capoeta group, the Aralo-Caspian group) comprises very closely related taxa characterized by large scales and plain body (absence of irregular black spots on the dorsal half of the body) distributed in Aralo-Caspian water bodies ( capoeta , ekmekciae , heratensis , gracilis , sevangi ) that has been recently diverged and could be considered as Very Young Evolutionary Group.

The molecular status of nine species of the genus Alburnoides from different river drainages in Iran and additionally by seven species from Europe was assessed. mtDNA COI gene sequences from freshly collected specimens and available NCBI data revealed four major phylogenetic lineages. Based on the results, a distinct taxon from the Cheshmeh Ali (Ali Spring), a Damghan River tributary in the endorheic Dasht-e Kavir basin, northern Iran, which is the closest sister to Alburnoides namaki (Namak Lake basin) + Alburnoides coadi (Nam River in the endorheic Dasht-e Kavir basin) is considered as a new species, Alburnoides damghani sp. n. It is distinguished from other Alburnoides species in Iran by a combination of character states including: a weakly-developed, variably-scaled, ventral keel from completely scaleless to completely scaled, a short snout with the tip of the mouth cleft on a level with the lower margin of the pupil or slightly lower, a small eye (eye horizontal diameter slightly to markedly less than interorbital width), commonly 8½ branched dorsal-fin rays, commonly 11-12½ branched anal-fin rays, 40-46(47) total lateral-line scales, 2.5-4.2 or 2.5-4.1 pharyngeal teeth, gill rakers short and widely spaced, 6-8 in total, 39-41 (commonly 40), total vertebrae, (19)20(21) abdominal vertebrae, 19-21 (most commonly 20) caudal vertebrae, abdominal vertebral region most commonly equal to or longer than caudal region, and most common vertebral formulae 20+20 and 21+19.