Iran. J. Ichthyol. (June 2020), 7(2): 181-196 Received: February 20, 2020 © 2020 Iranian Society of Ichthyology Accepted: June 24, 2020 P-ISSN: 2383-1561; E-ISSN: 2383-0964 http://www.ijichthyol.org Research Article Hormuz River System as a micro hotspot of diversification for the aphaniid fishes in Iran Azad TEIMORI*1, Hamid Reza ESMAEILI2 1Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran. 2Ichthyology and Molecular Systematics Research Laboratory, Zoology Section, Department of Biology, College of Sciences, Shiraz University, Shiraz, Iran. *Email: [email protected] Abstract: The Hormuz River System (HRS) is located in the southern coastal plain of the Zagros Mountains. Two main river drainages i.e., Mehran and Kol are known from this region, which are directly discharged to the Persian Gulf. The HRS has surprising diversity for tooth-carp fishes (family Aphaniidae). The present study aims to accentuate this notable diversity and discuss the possible cause of diversification of the tooth-carps in the HRS. To date, 15 Aphaniid species have been discovered from the Iranian drainage basins. Among them, 10 species belong to the genus Aphanius, four species belong to the genus Aphaniops, and a single species belonging to the genus Paraphanius. The HRS by having four species (22% of the Iranian tooth-carps) demonstrated the highest diversity among the other Iranian basins. Of these, one belongs to the genus Aphanius (A. darabensis) and three species belong to the genus Aphaniops (A. furcatus, A. ginaonis, and A. hormuzensis). By considering the degree of endemicity of the tooth-carps fauna relative to the territorial boundaries of drainages, the HRS has the highest endemicity, in which 31% of the Iranian endemic tooth- carp species present only in the HRS. The last connection of the Makran Basin with the HRS dates back to the late Pliocene and lower Pleistocene about 1.8 million years ago. Also, the other vicariance-based events like those events related to the last glacial maximum (21000- 18000 BP), population migration during the Early Holocene sea-level rise, and the Holocene to present-day have promoted the intra- and interspecific differentiation of tooth-carps in the HRS. Also, the geological situation of the HRS provided various extreme environmental conditions, which caused a particular increase in the diversification of the tooth-carp species. Keywords: Aphanius, Aphaniops, Paraphanius, Extreme ecological condition, Geological history. Citation: Teimori, A.& Esmaeili H.R. 2020. Hormuz River System as a micro hotspot of diversification for the aphaniid fishes in Iran. Iranian Journal of Ichthyology 7(2): 181-196. Introduction 2012a). Based on the geological estimation, it has The Hormuz River System (HRS) includes several been separated from the other neighboring river river drainages locating in the southern coastal plain drainage (i.e., Helleh and Mond in the west and of the Zagros Mountains, southern Iran. The HRE Minab/Makran in the east) since the late Pliocene and drains into the Persian Gulf, near or at the Strait of Pleistocene (Hatzfeld et al. 2010). The last Hormuz (Fig. 1). It is separated in the west from the connection of the Makran Basin with the HRS Helleh and Mond River drainages (Persis) by the probably dates back to the late Pliocene and lower Kazerun Fault System (KFS), which separates the Pleistocene (i.e., 1.8 million years before the present) North Zagros from the Central Zagros, and in the (Regard et al. 2004). east, it is separated from the Minab River drainage In addition to the geological events, which have (Makran) by the Zendan Falt System (ZFS) (Regard been considered to be responsible for the isolation of et al. 2004; Hatzfeld et al. 2010; Teimori et al. the HRS from the other basins (Regard et al. 2004; 181 Iran. J. Ichthyol. (June 2020), 7(2): 181-196 Fig.1. The geographic location of the Hormuz River System (HRS) in the southern coastal plain of the Zagros Mountains, southern Iran. The HRE drains into the Persian Gulf, near or at the Strait of Hormuz. Hatzfeld et al. 2010), the local geologic events within the HRS have also been caused the isolation of hydrological networks and created various habitats (e.g., hot sulfuric springs, and river subsystems). This environment diversity and also habitat fragmentation caused a particular increase in fish species diversity of the HRS (e.g., Esmaeili et al. 2010, 2016; Teimori et al. 2012a, 2014, 2018). Regarding of hydrological networks, none of the rivers in the HRS has permanent water. The principal rivers in this region are Kol and Mehran Rivers. Both of these river drainages belong to the big Persian Gulf basin and drains directly into the Persian Gulf near Fig.2. Distribution of warm springs in Hormozgan the Strait of Hormuz (Fig. 1). Rainfall in HRS is low Province (Based on Hormozgan Regional Water Company data). and irregular and streams are not always perennial, while Qanats and spring-stream systems are the Hormozgan region, which are located totally in important refuges for the fish species and also other the central and western parts of the Hormuzgan organisms (Coad 1996). Besides, the warm springs Province (Fig. 2). In general, the water temperature are one of the most common surface indicators of in these springs varies from 24 to 50°C. Moreover, geothermal resources in the HRS, and also surface the flow rate of these springs is largely different so water is often rich with salt and sulfur (Porkhial et al. that it differs from a minimum low value of about 2013). 0.2l/s to a maximum amount of warm water for According to the Hormozgan Regional Water Genow spring, which is more than 170l/s (Porkhial et Company data, there are at least 26 warm springs in al. 2013). Most of the springs have neutral pH, and 182 Teimori and Esmaeili - Hormuz River System as a micro hotspot of diversification for the aphaniid fishes in Iran The tooth-carp fishes of the family Aphaniidae. The tooth-carp fishes (family Aphaniidae) belong to the fin-rayed fish, Order Cyprinodontiformes. Unlike the members of family Cyprinodontidae, which are distributed in the New World (North and South America), the family Aphaniidae is native to the Old World and widely distributed in the West Palearctic regions (Wildekamp 1993; Freyhof et al. 2017). To date, 44 tooth-carp species are discovered as valid in the Old World (Wildekamp et al. 1999; Coad 2000, 2009; Hrbek & Meyer 2003; Hrbek et al. 2006; Esmaeili et al. 2014b; Teimori et al. 2012a, 2014, Fig.3. Location of geothermal regions in Hormozgan Province (Based on Hormozgan Regional Water 2018). The high species diversity seems to be found Company data). in Southwestern Asia (Near East), particularly in the inland waters of the Anatolia and the Iranian Plateau. the others are slightly acidic. Also, Chloride (Cl) Therefore, these two regions are known as the hot content of the warm springs varies quite spot for the tooth-carp fishes in the world. considerably, ranging from 20 to 11180mg/l Generally, the members of the family Aphaniidae (Porkhial et al. 2013). are characterized by relatively a thick oval body, The previous study on the location of warm large to moderate cycloid scales, and superior mouth springs in the Hormozgan Province revealed that with tricuspid teeth. Some morphological almost all of them are related to salt domes especially characteristics of the genus are as follows; dorsal fin in its western parts (Porkhial et al. 2013). In many positioned somewhat posteriorly 8-14 branched rays, cases, each salt dome has a distinct warm spring (Fig. lateral line system present only on the head, and anal 3). It means that some of the salt domes have suitable fin with 8-15 branched rays. An important distinctive conditions to create a geothermal resource and for all of the aphaniid species is clear sexual geothermal fluids can reach the surface in every dimorphism. corner of salt dome. Also, there are several hot Ecologically, most species of these fishes are sulfuric springs such as; Genow at the north of small up to eight cm and tolerate a wide range of Bandar-e-Abbas (29°24'07.9˝N, 51°16'35.4˝W), temperature and salinity regimes (Wildekamp 1993; Khurgu (27°31'34.1˝N, 56°28'08.2˝W), Faryab our field observations). These ecological abilities (27°25'16.2˝N, 54°16'28.0˝W), Khamir (26°58' allow them to translocate via drainage shifting and 25.9"N, 55°32'26.8˝W). These springs provided promote survival of relict populations in restricted special extreme ecological conditions (i.e., high habitats (Echelle & Echelle 1992; Teimori et al. water temperature, more than 37°C, sulfuric water 2018). The most common mechanism of and high salinity) for the living of aquatic organisms diversification for the tooth-carp fishes is proposed to including fishes. Most of these habitats are inhabited be the allopatric isolation by which many species by the tooth-carp fishes (family Aphaniidae) have been evolved in the near east and the (Reichenbacher et al. 2009; Esmaeili et al. 2014a,b; neighboring regions (Hrbek & Meyer 2003; Hrbek et Teimori et al. 2012a, 2014, 2018) and two endemic al. 2006; Teimori et al. 2012b, c; Nasrolah cichlid fish, Iranocichla hormuzensis and I. persa Pourmoghadam et al. 2014; Ariyaee et al. 2018). The (Esmaeili et al. 2010, 2016, 2018; Schwarzer et al. particular examples are the evolution of the tooth- 2017). carp species inhabited the inland drainages restricted 183 Iran. J. Ichthyol. (June 2020), 7(2): 181-196 to the Zagros Mountains in Iran (Hrbek et al. 2006; Material examined: Aphanius darabensis: ZM-CBSU Esmaeili et al.