Length"weight relationship for two flounder species from Iranian waters of the Persian Gulf

The length-weight (LWR) relationship was estimated for the first time for two flounder species viz. Pseudorhombus elevatus Ogilby, 1912 and Solea elongata Day, 1877 from Iranian waters of the Persian Gulf. Fishes were collected using fishing boat during August to December 2017. No information is available in FishBase regarding the LWRs of these species. The b values of the LWR was 2.98 for P. elevatus and 3.10 for C. elongate, and the r2 values are 0.996 and 0.989, respectively. These estimates can be used for estimation of biomass of the studied fishes employing length frequency distributions

Ultramicroscopy of structures involved in the posterior region of scales in two flathead fishes (Teleostei: Perciformes)

Morphology of structures involved in the posterior region of scales in two flathead fish species viz. Platycephalus indicus and Grammoplites suppositus was studied using ultramicroscopy. The fish individuals were divided into three size groups based on their standard lengths and their scales were removed from four body regions. The microscopic observations indicated that the scales of both species were ctenoid. The posterior margin of all scales was formed by two rows of ctenii. Typically, the shape of the posterior region of scales in P. indicus was crescent, while it was triangular in G. suppositus. The number of ctenii in the scales of P. indicus was minimum 12 and maximum 60, while in G. suppositus it was minimum 6 and maximum 38. Moreover, the results indicated that the number of ctenii was increased during fish development because the smaller fishes have fewer ctenii in their scales than the adults, while, their general morphology has not been changed properly. This developmental change was significantly higher in P. indicus than G. suppositus. The increase of ctenii during fish development allows greater flexibility in movement. In conclusion, modification in the ornamentations of the posterior region has a hydrodynamic function and they are subject to modification during the fish development. The ctenii varying considerably in the number and could be easily counted, therefore, could be used as an appropriate taxonomic character at least in flathead fishes or even other fish groups

The sagittal otolith morphology of four selected mugilid species from Iranian waters of the Persian Gulf (Teleostei: Mugilidae)

The members of mugilid species are usually difficult to recognize because of the well-known similarity observed in their external morphology. Nevertheless, their identification is very important for local fisheries management and conservation action. Therefore, in the present study we applied otolith morphology to evaluate its significance in identification of four selected mugilid species; Chelon subviridis (Valenciennes, 1836), Liza klunzingeri (Day, 1888), Ellochelon vaigiensis (Quoy & Gaimard, 1825) and Mugil cephalus Linnaeus, 1758 occurring in the Iranian waters of the Persian Gulf in southern Iran. The results indicated several otolith features to be important for identification of the selected mugilid species as follow; the position and sulcus centrality, the curvature of the cauda, and the type of anterior and posterior regions. Based on the total approach evidences, we conclude that otolith morphology in mugilid fishes can be evidently used for the species identification and probably estimation of their phylogeny. The findings are in agreement with the previous studies which documented taxonomic importance of otolith morphology

Reproductive biology of two sympatric species of tooth-carps: Aphanius hormuzensis and Aphanius furcatus, from south of Iran (Teleostei: Aphaniidae)

Some aspects of the reproductive biology of two endemic tooth-carps, Aphanius hormuzensis and A. furcatus, from southern Iran, were studied by regular monthly collections throughout one year. Significant differences were observed between the total number of females and males, females being more abundant. Based on the pattern of reproductive indices including the gonado-somatic index and Dobriyal Index, it was concluded that these fishes spawn in April and May. The estimated absolute fecundity of A. hormuzensis ranged from 78 (TL = 32.2 mm) to 730 (TL = 51.1 mm), with a mean value of 219.78±66.50 oocytes per fish based on 15 females. The relative fecundity ranged from 68.45 to 518.54 oocytes/g body mass (Mean±S.D: 237.67±96.87 oocytes/g). For A. furcatus, the estimated absolute fecundity ranged from 53 (TL = 26.9 mm) to 102 (TL = 32.04 mm), with a mean value of 93.73±45.37 oocytes per fish based on 15 females. The relative fecundity ranged from 22.41 to 123.65 oocytes/g body mass (Mean±S.D: 64.98±23.37 oocytes/g). Due to overlapping of spawning season in these two sympatric species, it seems that other pre- and post-zygotic factors are responsible for absence of natural hybrids in the studies tooth-carps in the Mehran River

New osteological and morphological data of four species ofAphaniops(Teleostei;Aphaniidae)

Aphaniops dispar, widespread around the Arabian Peninsula, was recently separated in four species (A. dispar,A. hormuzensis,A. kruppi,A. stoliczkanus) by molecular results and colour patterns, but the morphological differences are small and call for more studies. Here we report differences in skeleton and median fin osteology of these species. In addition, we introduce the term 'modified caudal vertebra' to describe caudal vertebrae that are not directly associated with caudal ray support but are visibly modified from a 'usual' caudal vertebra.Aphaniops hormuzensis, an endemic species to southern Iran, has a significantly higher number of modified caudal vertebrae compared to the more widespreadA. stoliczkanusandA. dispar, and also toA. kruppi. This is a surprising result as the caudal skeleton and related structures of the posterior caudal vertebral column have yielded successful results in separating between families or genera, but there are only a few studies that have examined these structures for their role in species diagnosis. Our study also highlights that state-of-the-art methods in X-raying and improved staining procedures assist in the discrimination of superficially similar species

Diversificación e historia zoogeográfica del Pleistoceno superior al Holoceno en Aphanius dispar determinada a partir de la morfología del otolito

Aphanius dispar (Rüppell, 1829) is a common marine-euryhaline teleost fish in the Near East that has undergone considerable intraspecific differentiation. Otolith morphology is used to analyse the diversity within A. dispar in the Gulf of Oman (Sea of Oman) and the Persian Gulf. A total of 134 individuals from lagoons and inland habitats of Oman, the United Arab Emirates and southern Iran are analysed. The results revealed that otolith traits that are under genetic control are strikingly different from those that are under the influence of environmental factors. A clear spatial structure of the populations is detectable, suggesting that the environmental flexibility of A. dispar, vicariance events during the last glacial maximum (21000-18000 BP), dispersal in the course of the Early Holocene sea-level rise, and Holocene to present-day interruption of gene flow at the Strait of Hormuz have shaped the intraspecific differentiation of A. dispar. These factors may also be responsible for diversification within other marine-euryhaline fishes in the Near East and Mediterranean Sea, and thus the findings can contribute to successful conservation management.Aphanius dispar (Rüppell, 1829) es un teleósteo eurihalino común en aguas de Oriente Medio que presenta una considerable variación intraespecífica. El presente trabajo estudia la diversidad de A. dispar entre especímenes del Mar de Omán y del Golfo Pérsico a partir de la morfología de los otolitos. Se han analizado un total de 134 individuos procedentes de lagunas salobres y aguas interiores procedentes de Omán, Unión de Emiratos Árabes e Irán. Los caracteres morfológicos de los otolitos regulados genéticamente son distintos de los influenciados por factores ambientales. Se ha detectado una estructura espacial de las poblaciones, sugiriendo una plasticidad ambiental de A. dispar, un proceso de vicariancia durante la última glaciación (21000-18000 AP), una dispersión durante el aumento del nivel del mar a inicios del Holoceno y una interrupción del flujo genético en el estrecho de Ormuz desde el Holoceno a la actualidad. Los factores descritos podrían ser los causantes de la diversificación en otros peces eurihalinos de Oriente Medio y del Mar Mediterráneo y determinarlos podría contribuir a su conservación

Do different populations of Aphanius dispar in Southern Iran form Operational Taxonomic Units (OUTs)?

Deciphering the exact fundamental relations of morphological differentiation among isolated populations of animal species is generally difficult. Usually changes in morphology are resulted from adaptation to different environmental conditions (ecoplasticity) or represent an expression of genetic differences and/or gene pool pauperization, and in most instances, however, changes in morphology are the result of the interplay between environmental factors and genetic plasticity. In this study, the morphology and molecular phylogenies of common tooth-carp populations (Aphanius dispar) were studied in three basins in Southern part of Iran to discuss an important aspect relate to the question whether morphologically differentiated populations of a single species function as Operational Taxonomic Units. All morphological analyses were revealed significant and strong morphological differentiation between the populations that corresponds well with their zoogeography and their molecular phylogeny in geographically isolated basins. Therefore, it can be concluded that when the interaction between gene flow among populations and natural selection is resulted owing to a long evolutionary history, then the observed morphological differences can be functioned as different Operational Taxonomic Units (OTUs) in subspecies or even species levels. In addition, biological characteristics of the A. dispar, its high tolerance, geological and ecological conditions in Southern Iran are the main factors that increase chance of reproductive isolation and genetic diversity in this region