Number Of Gill Rakers Research Articles

A new species of sinistral flatfish of the genus Chascanopsetta (Teleostei: Bothidae) from off Papua New Guinea, western Pacific Ocean.

Left-eyed flounders of the genus Chascanopsetta Alcock 1894 (Bothidae) occur in the Indian, Pacific, and Atlantic oceans at depths ranging from 120 to 1500 meters. They possess some unique features in bothid fishes including a strongly compressed and elongated body and a tremendously large mouth. Currently, nine species of Chascanopsetta are recognized, and three of them (C. micrognatha Amaoka Yamamoto 1984, C. lugubris Alcock 1894 and C. prognatha Norman 1939) are distributed in the West Pacific. We collected 25 specimens of Chascanopsetta during 11 biodiversity expeditions carried out mainly in the West Pacific. Among them, eight specimens taken off Papua New Guinea present morphological features that differ from those of the three nominal species known in the West Pacific. In this study, we examined these eight specimens of unknown affinity and compared their morphology to that of specimens of other congeneric species. Results of these comparisons showed that these specimens represent an undescribed species of Chascanopsetta, named herein, C. novaeguineae sp. nov.. The new species resembles C. elski Foroshchuk 1991, which is known only from the Saya de Malha Bank in the western Indian Ocean, in having a high number of gill rakers (> 13). However, the combination of the following characters further distinguishes C. novaeguineae sp. nov. from C. elski: longer jaws, narrower interorbital width, and number of pseudobranches (21-25 vs. 26-27). The DNA sequences from the mitochondrial cytochrome oxidase subunit I (COI) gene from C. novaeguineae sp. nov. and other species were obtained and compared to confirm its taxonomic status and to infer its tentative phylogenetic position within the Chascanopsetta.

A new Chondrostoma species from the Büyük Menderes River Basin, Turkey (Teleostei: Cyprinidae)

In a study of the fishes of the Büyük Menderes River Basin, Aegean region of Turkey, two populations of Chondrostoma were found which showed clearly distinctive characters: the population from the Upper B. Menderes (Işıklı Lake) was attributed to C. meandrense Elvira, 1987, while the population from the Çine Stream in the Lower B. Menderes River basin proved to be a hitherto undescribed species: Chondrostoma turnai sp. n. Altogether 24 metric and 7 meristic parameters were compared. The new species is distinguished from C. meandrense and all other cogeners by a combination of the number of lateral line scales, the number of scale rows between the lateral line and the dorsal-fin origin, the number of scale rows of the lateral line and pelvic-fin origin, and the number of gill rakers on the first gill arch.http://www.zoobank.org/urn:lsid:zoobank.org:pub:811C213D-BEDD-4C8C-AE57-BFFA7964781A

Ecología trófica y rasgos ecomorfológicos de Triportheus magdalenae (Characiformes: Triportheidae) en el embalse El Guájaro, cuenca baja del río Magdalena, Colombia

This study integrated morphological characteristics and trophic ecology of Triportheus magdalenae in the El Guájaro reservoir, Atlántico, lower Magdalena River Basin, Colombia, based on the analysis of stomach contents and ecomorphological attributes. Five samplings were made between September 2014 and February 2016 considering each phase of the flood pulse. The fish were sampled using traditional fishing gear such as nets and trawls. The index of food importance (IAi %) was used to establish the dietary habits of the species, and the variation of the diet at interspecific level, and the vacuity coefficient (CV %) was also calculated. The Levins index standardized by Hurlbert (BA) was used to evaluate the amplitude between sizes, sex and hydrological phases. The oropharyngeal structures and the digestive tract were characterized, which together with morphological measurements, allowed and analyze 11 ecomorphological traits related to the use of habitat, such as position in the water column, and the exploitation of a particular trophic resource. The relationship between the ecomorphological traits and the diet of the species was analyzed by canonical correspondence analysis (CCA). We analyzed 89 individuals (34 - 124 mm SL). Triportheus magdalenae was classified as carnivore/zooplanktivore, and has a narrow trophic niche (BA = 0.12). Showed a high exploitation of zooplankton (95.9 % IAi), mostly Cladocera (Ceriodaphnia sp.) and Copepoda (Notodiaptomus sp. and Thermocyclops sp). The youngest juveniles (34 - 190 mm SL) also consumed allochthonous insects (3.4 % IAi).The ecomorphological traits that contributed the most to this trophic specialization were the relative length of the gillrakers (LRBE) and the number of gillrakers (NBE), which varied significantly from the smaller to the larger ones, with an increase in both number as well as in length as individuals grow, which explains the strongly marked degree of specialization on zooplankton in adults, since they present a greater degree of efficiency in the process of filtering. The vacuity coefficient was high (54 %), which could be associated with a decrease in the density of zooplankton populations, especially during the time of lower waters strongly influenced by the EL NIÑO event, however the observed diet (22 items food) corresponded to 80 % of the diet estimated (28 estimated food items).

Secondary Intergradation of Various Forms of Pidschian-Like Whitefishes (Coregonus lavaretus sensu lato, Coregonidae) in the Water Bodies of the Altai-Sayan Mountains

The purpose of this work is to study the interaction of morphologically similar forms of pidschianlike whitefishes of the Coregonus lavaretus complex inhabiting a limited area in the riverine-lacustrine system of the Bolshoy Abakan River basin. Sequences of the 16S-ND1 fragment of the mitochondrial DNA and the first intermediate transcribed spacer ITS1 of the nuclear DNA are determined. It is shown that whitefish populations differ based on the gill raker numbers and the complex of plastic traits. Analysis of the 16S-ND1 fragment of the mtDNA revealed several divergent lineages, which is confirmed by the study of the ITS1 of the nDNA. As a result, it is shown that the riverine-lacustrine system is inhabited by two genetically divergent whitefish populations. The results of the study support the hypothesis of multiple hybridization between slightly differentiated forms/populations of whitefishes during the postglacial period. As a result of the studies carried out, the hypothesis about the origin and possible ways of migration of some phylogenetic lineages of whitefishes in the water bodies of the Yenisei River basin is proposed.

DNA barcoding revealed a new species of Neolissochilus Rainboth, 1985 from the Kaladan River of Mizoram, North East India

Neolissochilus kaladanensis sp. nov., a new cyprinid species, is described from the Kaladan River drainage of Mizoram. It differs from all other valid Neolissochilus species in having higher number of gill rakers on the lower arm of the first gill arch (13–14 vs. 12 or below in all the species). The analysis of mitochondrial gene cytochrome c oxidase subunit I (COI) sequences separated N. kaladanensis sp. nov. from all other Neolissochilus and Tor species with an average genetic distance of 6.0%. It is further separated from the morphologically most similar species N. hendersoni and N. soroides by a genetic distance of 6.7% and 6.8%, respectively. Based on the lowest BIC and AICc scores, best fit model for COI dataset was TN93 + G + I, out of 24 different nucleotide substitution models tested. The maximum-likelihood (ML) phylogenetic tree was constructed using the COI sequences of representative Neolissochilus and Tor species. The anomalies observed among the GenBank sequences of the genera Tor and Neolissochilus are also discussed.

Generic assignment of Leuciscus kurui Bogutskaya from the upper Tigris drainage, and a replacement name for Alburnus kurui Mangit Yerli (Teleostei: Leuciscidae).

The generic position of Leuciscus kurui Bogutskaya, 1995 is reviewed through a comparison of morphological and molecular characters (COI). The molecular data place L. kurui in Alburnus, close to Alburnus timarensis from the Lake Van basin. Alburnus kurui (Bogutskaya) is distinguished from this species by lacking a ventral keel and possessing both a very low number of gill rakers and midlateral scales. Alburnus selcuklui, from the upper Tigris drainage, cannot be distinguished from the widespread A. sellal and is therefore treated as a synonym of this species. Alburnus kurui Mangit Yerli, 2018 is a junior secondary homonym of A. kurui (Bogutskaya, 1995) and A. carianorum is proposed as its replacement name. Several specimens of Alburnus caeruleus and Alburnus heckeli shared the same haplotypes as some A. sellal and therefore these species cannot always be distinguished by mitochondrial molecular characters. Alburnus caeruleus and A. heckeli are treated as valid species. Other individuals of A. caeruleus have haplotypes very different from A. sellal, and A. heckeli is well distinguished from A. sellal by having more gill rakers. The Lake Van basin as a separate freshwater ecoregion and the treatment of several species of Alburnus in synonymy of A. mento are discussed.

Diversifying selection drives parallel evolution of gill raker number and body size along the speciation continuum of European whitefish.

Adaptive radiation is the evolution of ecological and phenotypical diversity. It arises via ecological opportunity that promotes the exploration of underutilized or novel niches mediating specialization and reproductive isolation. The assumed precondition for rapid local adaptation is diversifying natural selection, but random genetic drift could also be a major driver of this process. We used 27 populations of European whitefish (Coregonus lavaretus) from nine lakes distributed in three neighboring subarctic watercourses in northern Fennoscandia as a model to test the importance of random drift versus diversifying natural selection for parallel evolution of adaptive phenotypic traits. We contrasted variation for two key adaptive phenotypic traits correlated with resource utilization of polymorphic fish; the number of gill rakers and the total length of fish, with the posterior distribution of neutral genetic differentiation from 13 microsatellite loci, to test whether the observed phenotypic divergence could be achieved by random genetic drift alone. Our results show that both traits have been under diversifying selection and that the evolution of these morphs has been driven by isolation through habitat adaptations. We conclude that diversifying selection acting on gill raker number and body size has played a significant role in the ongoing adaptive radiation of European whitefish morphs in this region.

Ongoing niche differentiation under high gene flow in a polymorphic brackish water threespine stickleback (Gasterosteus aculeatus) population

BackgroundMarine threespine sticklebacks colonized and adapted to brackish and freshwater environments since the last Pleistocene glacial. Throughout the Holarctic, three lateral plate morphs are observed; the low, partial and completely plated morph. We test if the three plate morphs in the brackish water Lake Engervann, Norway, differ in body size, trophic morphology (gill raker number and length), niche (stable isotopes; δ15N, δ13C, and parasites (Theristina gasterostei, Trematoda spp.)), genetic structure (microsatellites) and the lateral-plate encoding Stn382 (Ectodysplasin) gene. We examine differences temporally (autumn 2006/spring 2007) and spatially (upper/lower sections of the lake – reflecting low versus high salinity).ResultsAll morphs belonged to one gene pool. The complete morph was larger than the low plated, with the partial morph intermediate. The number of lateral plates ranged 8–71, with means of 64.2 for complete, 40.3 for partial, and 14.9 for low plated morph. Stickleback δ15N was higher in the lower lake section, while δ13C was higher in the upper section. Stickleback isotopic values were greater in autumn. The low plated morph had larger variances in δ15N and δ13C than the other morphs. Sticklebacks in the upper section had more T. gasterostei than in the lower section which had more Trematoda spp. Sticklebacks had less T. gasterostei, but more Trematoda spp. in autumn than spring. Sticklebacks with few and short rakers had more T. gasterostei, while sticklebacks with longer rakers had more Trematoda. spp. Stickleback with higher δ15N values had more T. gasterostei, while sticklebacks with higher δ15N and δ13C values had more Trematoda spp. The low plated morph had fewer Trematoda spp. than other morphs.ConclusionsTrait-ecology associations may imply that the three lateral plate morphs in the brackish water lagoon of Lake Engervann are experiencing ongoing divergent selection for niche and migratory life history strategies under high gene flow. As such, the brackish water zone may generally act as a generator of genomic diversity to be selected upon in the different environments where threespine sticklebacks can live.

Impact of the huge 2011 Tohoku-oki tsunami on the phenotypes and genotypes of Japanese coastal threespine stickleback populations

On March 11, 2011, a large earthquake occurred, causing a tsunami which struck the Pacific coast of northeast Japan. We investigated the ecological and genetic effects of the large tsunami on the threespine stickleback (genus Gasterosteus) populations in Otsuchi Town, which was one of the most severely damaged areas after the tsunami. Our environmental surveys showed that spring water may have contributed to the habitat recovery. Morphological analysis of the stickleback before and after the tsunami showed morphological shifts in the gill raker number, which is a foraging trait. Genetic analyses revealed that the allelic richness of one population was maintained after the tsunami, whereas that of another decreased in 2012 and then started to recover in 2013. Additionally, we found that the large tsunami and ground subsidence created new spring water-fed pools with sticklebacks, suggesting that the tsunami brought sticklebacks into these pools. Genetic analysis of this population showed that this population might be derived from hybridization between freshwater Gasterosteus aculeatus and anadromous G. nipponicus. Overall, our data indicate that tsunamis can influence morphologies and genetic structures of freshwater fishes. Furthermore, spring water may play important roles in the maintenance and creation of fish habitats, faced with environmental disturbance.

Detection and morphological characteristics of “Kunimasu” (Oncorhynchus kawamurae)/”Himemasu” (O. nerka) hybrids in Lake Motosu, Yamanashi Prefecture, Japan

A recently discovered transplanted population of “Kunimasu” (Oncorhynchus kawamurae) in Lake Saiko, Yamanashi Prefecture, Japan, extinct in its original habitat, has been reported as almost never hybridizing with sympatric “Himemasu” (O. nerka). However, analyses of microsatellite and mitochondrial DNA markers disclosed extensive hybridization between these two species in Lake Motosu, Yamanashi Prefecture, a second lake to which Kunimasu had been transplanted. The rates of purebred Kunimasu, Kunimasu/Himemasu hybrids and purebred Himemasu were 0 %, 64.3 % and 35.7 %, respectively, and hybrid specimens had intermediate numbers of pyloric caeca and gill rakers compared with the parental species.

Description of two deep-water fishes of the genusDiplotaxodon(Teleostei: Cichlidae) from Lake Malaŵi, Africa

Abstract Two species of haplochromine cichlid fishes of the genus Diplotaxodon Trewavas, endemic to Lake Malaŵi are described: Diplotaxodon longimaxilla, new species, and Diplotaxodon altus, new species. Diplotaxodon altus is diagnosed from other species in the genus based on body depth (35.1–37.8% SL), number of gill rakers (21–26), and a smaller cheek depth (18.2–20.0% HL). Diplotaxodon longimaxilla is delimited from other Diplotaxodon spp. based on body depth (28.9–32.4% SL), horizontal eye diameter (HED 27.1–32.1% HL), smaller cheek depth (15.2–19.4% HL), and number of lateral-line scales (35–38). Other authors have indicated that several other Diplotaxodon spp. occur, but too few specimens were available to permit detailed comparisons. The two new species occur sympatrically at depths of between 40–130 m. Specimens of Diplotaxodon altus were sampled from nets deployed at night using light attraction, while specimens of D. longimaxilla were sampled from nets operated both at night and day. We further ...

Diagnostic features and taxonomy of the Mediterranean species of the big-scale sand smelts belonging to Atherina boyeri group (Atherinidae)

Morphological studies of the big-scale sand smelt from the group Atherina boyeri sensu lato were carried out using the materials of the museum collections from the Mediterranean Sea, the Black Sea, and the Sea of Azov. It has been shown that low-raker sand smelt belonging to the species A. boyeri sensu stricto, and multi-raker sand smelt, referred to the A. mochon species, are differentiated by a complex of morphological features: the number of gill rakers, the shape of scales, the length of the ascending process of praemaxillare, and the shape of the lower margin of maxillare. The key for their identification is presented. It is assumed that A. mochon is not a native Black Sea species but belongs to the invasive species originating from the Mediterranean Sea. The isolation of two cryptic species is discussed. The neotype of A. pontica is designated.

АНАЛИЗ ЛИНЕЙНО-ВЕСОВЫХ ПОКАЗАТЕЛЕЙ И МЕРИСТИЧЕСКИХ ПРИЗНАКОВ СИБИРСКОЙ СТЕРЛЯДИ ACIPENSER RUTHENUS MARSIGLII (BRANDT, 1833) БАССЕЙНА РЕКИ ИРТЫШ

In the basin of the Irtysh River, one of the mass representatives of the Acipenseridae family is the Siberian sterlet Acipenser ruthenus marsiglii (Brandt, 1833). Today, the catch of sterlet in this region is allowed only as control catches for scientific research. Poaching causes a great loss for the species. In the period from 2013-2016 there were held 44 forensic and ichthyologic examinations, including 26 criminal case examinations and 18 expert examinations on the materials of the Register of Complaints concerning Offences. 665 species of Siberian sterlet were caught illegally. In these illegal catches, species with a body length of 31.0 to 40.9 cm were most often found (this made 55.2% of all years of expert examinations), species of 21.0-30.9 cm length made 26.3%, of 41.0 to 50.9 cm length made 16.4%. When analyzing the total mass of fish caught illegally from 2013 to 2016, it was found that species having a mass 100.0-199.9 g were most often found, their share of the total number of fish was 51.6%. Species with a mass 200.0 - 299.9 g made 17.1%; with a mass 0-99.9 g - 15.6%. In this study, the minimum number of lateral beetles in sterlet was 49; maximum - 69; dorsal beetles 11-18; the number of gill rakers corresponded to the specific number and varied from 17 to 29 (mean 14). The meristic features of the species under study correspond to the subspecies Siberian sterlet Acipenser ruthenus marsiglii (Brandt, 1833).

Two new goatfishes of the genus Upeneus (Mullidae) from Australia and Indonesia

Two new goatfishes of the genus Upeneus (Mullidae) belonging to the putative japonicus species group are described and compared with congeneric species using a large set of meristic, morphometric and colour characters. Upeneus farnis n. sp. Uiblein & Peristiwady is described based on 14 adult specimens (> 65 mm SL) collected at the local fish market of Bitung, NE Sulawesi, Indonesia. Upeneus spottocaudalis n. sp. Uiblein & Gledhill is described based on 16 adult and seven subadult specimens (< 65 mm SL) specimens collected by trawling surveys off NE Australia and one non-type adult specimen collected off southern Indonesia. The new species differ from all other congenerics in the combination of dorsal-fin spine, pectoral-fin ray and gill raker numbers, body and head depth, length of head, snout, barbels and paired fins, height of anal and dorsal fins, eye size, and body, barbel and caudal-fin colour patterns. When compared in detail with the 12 other species of the japonicus group, Upeneus farnis n. sp. can be distinguished by smaller eyes, shallower anal and second dorsal fins, more pectoral-fin rays and gill rakers, and the lower caudal-fin lobe almost completely dark pigmented. Upeneus spottocaudalis n. sp. differs from the other japonicus-group species in larger eyes, higher second dorsal fin, pectoral fin shorter than pelvic fin, and presence of rounded, dark spots on the lower caudal-fin lobe. Subadults differ from adult U. spottocaudalis n. sp. mainly in longer pelvic fins. The high diversity of Upeneus species in relation to divergence in colour patterns and the need of further taxonomic exploration of the genus Upeneus is discussed.

Occurrence of sympatric charr groups, Salvelinus, Salmonidae, in the lakes of Kamchatka: a legacy of the last glaciations.

Six postglacial lakes were studied along both sides of the Kamchatka central mountain range, Russia. Pairs of local morphotypes of species of Arctic charrs, Salvelinus spp., have previously been described from the southernmost lakes while the fish fauna of the four northernmost lakes was studied here for the first time. Phenotypic data support the division of Kamchatkan lacustrine charrs into two groups according to the number of gill rakers and pyloric caeca, as well as snout-dorsal and snout-ventral distances (MANOVA, P < 0·001). These groups respectively correspond to phenotypes commonly referred to as Salvelinus malma and Salvelinus taranetzi. To clarify the identity of these groups, D-loop and cytochrome b (cytb) region sequences were analysed. Haplotype network analysis of mtDNA shows the salmonids inhabiting four lakes on the south and north are phylogenetically close to either Beringian S. malma or to S. taranetzi from the Chukotka and Kolyma River basins (the mean ± s.e. pairwise per cent sequence divergence is 0·006 ± 0·001). Phenotype-genotype discordance suggests that mitochondrial introgression between species has occurred in the two smallest lakes (<0·5 km2 ) in the central part of the peninsula. Identical haplotypes of D-loop and cytb regions were found for the populations of S. taranetzi from the most distant southern and northern lakes, indicating all lakes were colonized by both species simultaneously after the last glacial maximum. Salvelinus taranetzi may have colonized the Kamchatka peninsula from one or both of two different source regions: the Arctic Beringia and the northern coast of the Okhotsk Sea.

Hybridization between different lineages of pidschian-like whitefishes (Coregonus lavaretus pidschian, coregonidae) in water bodies of Southern Siberia

Summary: Background. The purpose of this work was studying of interaction between morphologically similar forms of the pidcshian-like whitefishes inhabiting restricted territory of riverine-lacustrine system situated in the Bolshoi Abakan Rriver basin.&#x0D; Material and methods. In the morphological analysis were used 141 whitefish individuals from Lake Karakul and 26 from the Bolshoi Abakan River. In the genetic analysis 11 and 26 whitefish individuals were used respectively. For them the sequences of a gene 16S-ND1 of mitochondrial DNA (mtDNA) and ITS1 of nuclear DNA (nDNA) were defined.&#x0D; Results. The whitefish populations clear differ on the gill raker numbers on the first branchial arch, growth. The analysis of the 16S-ND1 mtDNA genes variability revealed among them several divergent lineages and two lineages were revealed on the structure of ITS1 fragment of the nDNA.&#x0D; Conclusions. Based on the obtained data it is proved that two genetically divergent populations of the morphologically same forms of pidcshian-like whitefishes inhabiting the riverine-lacustrine system (the Bolshoi Abakan River Lake Karakul). Our results are supported a hypothesis of multiple hybridization between week differentiated populations/form of pidcshian-like whitefishes in habiting region during the postglacial period.

Taxonomic revision of the seasonal killifish genus Nothobranchius from Zanzibar, East Africa (Cyprinodontoidei: Aplocheilidae)

ABSTRACTNothobranchius guentheri and Nothobranchius melanospilus, the two seasonal killifishes of the genus Nothobranchius occurring in Zanzibar Island, Tanzania, were involved in past taxonomical mistakes and are still misidentified in museum collections. A historical review is herein presented and both species are redescribed on the basis of type material and recent collections. Nothobranchius guentheri, a popular aquarium fish, is endemic to Zanzibar, and N. melanospilus, geographically widespread in East Africa, occurring both in Zanzibar and in continental river basins. These species are distinguished by a series of morphological features not previously reported in the literature, including pre-dorsal length and relative position of the anterior portion of the dorsal-fin skeletal support and vertebrae; number of gill-rakers of the first branchial arch, caudal-fin rays, scales of the longitudinal series, series of scales around caudal peduncle, and vertebrae; frontal squamation; and arrangement and number of neuromasts of the supraorbital series. The present taxonomic revision comprising N. guentheri and N. melanospilus, the oldest species names of the genus in the East African biodiversity hotspot, is important to improve the knowledge of the genus in a region where its taxonomy is still problematic

Reappraisal of Synagrops Günther, 1887 with rehabilitation and revision of Parascombrops Alcock, 1889 including description of seven new species and two new genera (Perciformes: Acropomatidae).

An ongoing review of the fishes of the basal percoid family Acropomatidae has revealed that the genus Synagrops Günther, 1887 as it is currently understood is not a natural group. Species with a serrated pelvic-fin spine are here placed in the resurrected genus Parascombrops Alcock, 1889 (type-species: Parascombrops pellucidus Alcock, 1889), and the new, monospecific genus Caraibops n. gen. (type-species: Synagrops trispinosus Mochizuki & Sano, 1984). Parascombrops is unique amongst Acropomatidae in the combination of the presence of vacant 8th interneural space, a predorsal formula /0+0/0+2/ and an epaxialis attachment type 1. Caraibops n. gen. shares none of these characters and further differs from Parascombrops by an anal-fin formula of III + 9 (vs II + 7 or III + 6), and the absence of denticles on the ectopterygoid. Parascombrops is revised and now contains a total of 13 species, including 7 new: P. analis (Katayama, 1957), P. argyreus (Gilbert & Cramer, 1897), P. glossodon n. sp., P. madagascariensis n. sp., P. mochizukii n. sp., P. nakayamai n. sp., P. ohei n. sp., P. parvidens n. sp., P. pellucidus Alcock, 1889, P. philippinensis (Günther, 1880), P. serratospinosus (Smith & Radcliffe, 1912), P. spinosus (Schultz, 1940) and P. yamanouei n. sp. Synagrops adeni Kotthaus, 1970 and S. malayanus Weber, 1913 are treated as synonyms of P. pellucidus and P. philippinensis, respectively. Lectotypes are designated for P. philippinensis and S. malayanus. The main characters used to distinguish between the species of Parascombrops are: serration of other fin spines, number of gill rakers and pseudobranchial filaments, head profile, presence or absence of ridges on the preopercle, shape of 1st anal-fin pterygiophore, dentition on vomer, palatines and ectopterygoids, orbit diameter, pectoral-fin length, maximal body depth and otolith morphology. The genus Synagrops is here confined to two species, S. japonicus (Döderlein, 1883) and S. bellus (Goode & Bean, 1896), characterized by the apomorphic character of an otic capsule with a posteriorly open myodome, a basioccipital fossa and a very specialized otolith morphology. Synagrops is also characterized by the absence of pelvic-fin spine serrations. Two other species without a serrated pelvic-fin spine, originally described in Synagrops, are removed from this genus. Synagrops microlepis Norman, 1935 is separated into the monotypic Kaperangus n. gen., the only genus in the family with two supraneurals (cf. three in all other taxa). The second, Synagrops pseudomicrolepis Schultz, 1940 is re-assigned to the genus Verilus. The geographic distribution of Parascombrops as currently composed is discussed, and is shown to be primarily of West Pacific nature, with few species in the Indian Ocean and one in the tropical West-Atlantic (P. spinosus). The West Atlantic species Parascombrops spinosus is very closely related to P. mochizukii from the tropical northwestern Pacific, and the implications of this disjunct distribution are discussed. The high degree of speciation now recognized in Parascombrops species of the West-Pacific indicates that a diverse ecological adaptation within an overall pseudoceanic habitat may have played a major role in speciation, which would have remained obscured without adequate taxonomic resolution. Fossil, otolith-based records are also briefly discussed in the context. The extant Parascombrops argyreus and P. ohei are reported from the Pliocene of Japan, and Caraibops trispinosus has been recorded from the Pliocene of Venezuela.

Review of the Odontesthes perugiae species group from Río de La Plata drainage, with the description of a new species (Atherinomorpha: Atherinopsidae).

Specimens presently identified as belonging to Odontesthes perugiae species group from rio Paraná, rio Uruguay and rio Negro in Argentina, Brazil and Uruguay are revised. Two species are recognized: Odontesthes perugiae, type species of the genus with Odontesthes orientalis as a junior synonym, and a new species described herein. Odontesthes perugiae is redescribed and its distribution restricted to the lower rio Paraná, lower rio Uruguay and rio Negro basins. The new species is endemic from the upper rio Uruguay above Salto do Yucumã (Brazil) or Saltos del Moconá (Argentina) falls. Both species share with the remaining taxa included in the O. perugiae species-group (O. bicudo, O. ledae, O. mirinensis, and O. piquava) the possession of teeth of the outer row on dentary and premaxilla shorter than those in the inner row, being distinguished from them by the number of gill rakers, body measurements and some osteological characters.

The first record of Nile tilapia Oreochromis niloticus (L.1758) In the Diyala River /Buhriz

The Nile tilapia (Oreochromis niloticus) was recorded for the first time in Diyala River/ Buhriz.during september and October 2017. The total length has ranged from 155 mm to 200 mm with a total weight of 97.6 to 235.8 g. A number of gill rakers on the first arch gill of 27-30. The number of soft rays in the dorsal fin 12-13 and the spine 15 to 16. The anal fin with 9-10 in the soft rays and 3-3 on the spine. The number of soft rays in the pectoalfin 13. The body depth is 40.62% and body thickness is 16.29%. The eye diameter is 4.41%, the head length is 27% and the height is 35%, respectively and the length of the snout is 6%.