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Chondrichthyan egg cases are important elements for species-specific identification and also provide a valuable aid in determining a species spatial distribution, as well as for defining spawning areas. Considering the absence of a general key for the identification of the egg cases of the Mediterranean Chondrichthyes, this work aims to fill this gap by presenting a species-specific key based on morphological features of the egg case. The key was developed primarily analysing fresh egg cases dissected from the oviduct, egg cases collected from the seabed or found dried lying on the seashore, after species confirmation by DNA analysis. Original data were integrated with information scrutinized from literature. In order to improve species identification, a protocol for the standardized acquisition of morpho-biometric and meristic features is also provided as a pre-requisite for the appropriate use of the identification key. The total width and length included the horns, when they are not broken, are the parameters that best explain the assignment of the egg case to a specific species. [ABSTRACT FROM AUTHOR]

Chondrichthyan egg cases are important elements for species-specific identification and also provide a valuable aid in determining a species spatial distribution, as well as for defining spawning areas. Considering the absence of a general key for the identification of the egg cases of the Mediterranean Chondrichthyes, this work aims to fill this gap by presenting a species-specific key based on morphological features of the egg case. The key was developed primarily analysing fresh egg cases dissected from the oviduct, egg cases collected from the seabed or found dried lying on the seashore, after species confirmation by DNA analysis. Original data were integrated with information scrutinized from literature. In order to improve species identification, a protocol for the standardized acquisition of morpho-biometric and meristic features is also provided as a pre-requisite for the appropriate use of the identification key. The total width and length included the horns, when they are not broken, are the parameters that best explain the assignment of the egg case to a specific species. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the acute toxicity of ammonia and nitrite to three developmental stages of Pacific cod (Gadus macrocephalus) larvae (11, 22, and 35 days after hatching, with mean total lengths of 4.63 ± 0.14, 5.83 ± 0.17, and 7.46 ± 0.23 mm, respectively). The results showed for the first time that the acute toxicity of ammonia and nitrite is closely related to the age of Pacific cod larvae, and the acute toxicity of ammonia or nitrite increased with increased Pacific cod larval growth. Lethal concentrations (LC50) of un-ionized ammonia nitrogen (UIAN) for a 48-h exposure in 11-day post-hatch, 22-day post-hatch, and 35-day post-hatch Pacific cod larvae were 1.72, 0.69, and 0.32 mg L−1, respectively. The 48-h LC50 of nitrite nitrogen to Pacific cod larvae 11-day post-hatch, 22-day post-hatch, and 35-day post-hatch were 831.76, 269.15, and 223.87 mg L−1, respectively. The present findings demonstrate that the acute toxicity of ammonia for Pacific cod larvae is much higher than that of nitrite. [ABSTRACT FROM AUTHOR]

Somatic morphology and otolith shape were used to discriminate four samples ofAtherina boyerifrom three different habitats: Mellah lagoon (n = 269), Annaba Gulf (144 punctuated and 194 unpunctuated individuals) and Ziama inlet (n = 147) in eastern Algeria. For each individual, somatic morphology was described with 13 metrics and eight meristic measurements, while the otolith contour shape of 452 individuals from the three habitats was analysed using Fourier analysis. Then, two discriminant analyses, one using the 13 metric measurements and the other using Fourier descriptors, were used in order to discriminate populations ofA. boyeri. The results of the discriminant analyses based on the two methods were similar, and showed that this species could be discriminated into three distinct groups: (1) marine punctuated, (2) lagoon and marine unpunctuated and (3) estuarine. These results are consolidated by the comparison of the Mayr, Linsley and Usinger coefficient of difference for the meristic parameters according to the location origin, where the difference reached a racial or even sub-specific level for some characters, depending on which pairs of populations were compared. [ABSTRACT FROM AUTHOR]

The morphological study of the vertebral column ofCarangoides caeruleopinnatus(Rüppell, 1830) enabled the division of this bony structure into four morphologically distinct regions, and the drawing of characteristic-looking vertebral profiles. This regionalization is more complicated than the classical division in truncal and caudal parts only. These morphological descriptive parameters express a morphotype that may be linked with the carangiform mode of swimming of the onion trevally. [ABSTRACT FROM PUBLISHER]

The urohyal bone, located in the central part of the mandibular skeleton, plays an important role in the mouth opening-closing mechanism of fish, and is considered a synapomorphy in teleostean fish. Morphology of the urohyal bone in six species of Gerreidae (Diapterus brevirostris,D. auratus,Eugerres lineatus,E. plumieri,Eucinostomus entomelasandGerres cinereus) from the Pacific and Atlantic coasts of México was compared, using size and shape measurements. The main goal of the study was to explore the effectiveness of urohyal measurements in discriminating Gerreidae species. Morphological variation of urohyal bones, in terms of size and shape parameters, allowed species differentiation. Discriminant function analysis (DFA) significantly separated the six species with high classification rates (overall mean 92%). The G-test and Cohen’s kappa confirmed the high rates of classification success obtained by DFA. Circularity, Feret minimum, roundness, rectangularity and area were the main urohyal measurements explaining inter-specific variability. These results suggest the usefulness of urohyal bone morphology in differentiating Gerreidae species analyzed, highlighting the taxonomic value of the urohyal bone, until now never quantitatively evaluated as a diagnostic character in the classification of teleostean fish. [ABSTRACT FROM AUTHOR]

Populations of stream fishes exposed to different hydrodynamic, trophic, and physicochemical conditions may vary in their phenotypic traits in ways that influence local persistence. For example, gut morphology frequently varies with trophic position and food quality. As a result, one might expect gut morphology to differ between populations from watersheds with unique ecosystem characteristics, such as those occurring in urbanized streams. This study was an initial exploration to determine whether gut morphology ofCampostoma oligolepis(Largescale Stoneroller) differed between an urbanized stream and a less urbanized stream in northwest Georgia, USA. Individuals were collected in May and June 2011 and dissected to quantify the gut length and gut quotient. With standard length as a covariate, gut length was shorter in the urbanized stream, and gut quotients were significantly lower. Gut lengths were also significantly longer in May than in June. One possible explanation for this difference is spatial and temporal variation in food sources associated with urbanization, although alternative explanations exist. [ABSTRACT FROM AUTHOR]

This study aimed to contribute to understanding the role of changes in proportions related to variation in size in freshwater fish, particularlyRutilus rubilio,Squalius lucumonisandTelestes muticellus, from central Italy. The ontogenetic shape variation was described by a multivariate regression where the independent and dependent variables were size and a set of shape variables (the latter obtained from geometric morphometric analysis of 16 anatomical landmarks), respectively. Our analyses indicated: (1) proportional ontogenetic changes in several morphometric characters in all populations of the three species; (2) no geographical shape variation for each species; (3) interspecific differences. The main shape changes joining all the populations are the ocular area contraction, the tail peduncle enlargement, and the main changes involving the median body region. The shape variations showed similar modification patterns betweenR. rubilioandS. lucumonis(the silhouette passed from a streamlined to a more oval and higher shape for both species) and some differences betweenR. rubilioandS. lucumonisvs.T. muticellus(the latter approaching a more spindle-shaped body). The expression of these allometric trajectories may be associated with age-specific shifts in the ecological niche, optimizing some features such as foraging efficiency and movement. [ABSTRACT FROM AUTHOR]

The genusPseudoplatystomaincludes catfish species distributed throughout the fresh waters of South America. These species are important fisheries resources and play a significant ecological role due to their piscivorous and migratory habits. The taxonomy of this genus is still debated: traditionally, only three species have been recognised, but recently, this number was raised to eight. The validity of these eight morphospecies, however, was not confirmed by two subsequent molecular phylogenetic studies, which identified either five or four main clades. In this study, we focused on the two morphospecies restricted to the Orinoco basin,P. metaenseandP. orinocoense, which have been assigned to either the same or different clades in previous studies. We carried out cytogenetic analyses to describe their unknown karyotypes and to look for cytotaxonomic markers. We also analysed their mitochondrial sequences in order to assign the sampled specimens to the previously identified molecular clades. The two presumptive species show similar karyotypes (2n = 56, 42 biarmed and 14 uniarmed chromosomes) and cytogenetic features in terms of the constitutive heterochromatin distribution and the number and location of minor and major ribosomal genes. Thus, no species-specific chromosome markers could be identified. The analysis of cytochrome b and cytochrome oxidase I mitochondrial genes (carried out by retrieving all the mtDNAPseudoplatystomasequences available in GenBank) distributed the sampled specimens into two distinct molecular clades and confirmed the need to re-evaluate, by parallel morphological and molecular analyses, the monophyly of some lineages. [ABSTRACT FROM AUTHOR]

The article focuses on the teeth of albuliform fish (Teleostei, elopomorpha) found from the lower Cretaceous Wadhurst Clay formation in Southeast England. It mentions that the teeth of the said species were more distinct compared to those from other durophagous Early Cretaceous freshwater taxa. It states that most of the fossils from albuliform taxa were recorded from fully marine, estuarine, and saline lagoonal settings.

In 1989, TMP 89.127.3, a basal ichthyopterygian, was collected as a counterpart slab from the Vega-Phroso Siltstone Member (Lower Triassic) of the Sulphur Mountain Formation in east-central British Columbia, Canada. Previous investigations of its postcranial skeleton resulted in ambiguous taxonomic affinities, with it being identified as eitherGrippiacf.longirostrisorParvinatator wapitiensis. More recently, the part slab of TMP 89.127.3 was collected and prepared, revealing important new cranial data that permits its systematic relationships to be more thoroughly assessed and previously proposed taxonomic affinities to be tested. By integrating both cranial and postcranial data, phylogenetic analysis recovers TMP 89.127.3 andGrippiaas members of Grippidia, nested within Eoichthyosauria. TMP 89.127.3 can be distinguished fromGrippiaby possessing the following autapomorphies: metacarpal I with a notched peripheral shaft; cylindrical anterior teeth with a crown shape index >5.0; and a postfrontal-frontal contact at the rostral limit of the anterior margin of the supratemporal terrace. A new taxon,Gulosaurus helmi, is erected to accommodate this suite of features. The placement ofGulosaurus helmiwithin Grippidia reaffirms the Early Triassic distribution of this clade to include western and northern Laurasia, which is represented by outcrop in present-day Canada and Norway (Spitzbergen), respectively. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free atwww.tandfonline/UJVP [ABSTRACT FROM PUBLISHER]

Based upon fragmentary remains of dermal armor, a new form of arandaspid fish,Ritchieichthys nibili, gen et. sp. nov., is described from subsurface core material from the Katian (Late Ordovician) Nibil Formation of the Canning Basin, Western Australia.Ritchieichthys nibilirepresents the first documented record of a fish from the Ordovician of the Canning Basin. Allied to the previous descriptions of arandaspsids from the Amadeus and Warburton basins of the Northern Territory and New South Wales, respectively, this record extends the paleogeographic range of arandaspids across the hypothetical Ordovician Larapintine Seaway and increases the stratigraphic range of the Order Arandaspidiformes into the Katian. The hard tissue histology ofRitchieichthys nibiliconfirms the presence of a cellular dentine forming the bulk of the dermal armor ornament in arandaspids, a tissue that had not been directly observed previously, and confirms the presence of largely unconnected osteocytes within the dermal bone that forms the majority of the armor. [ABSTRACT FROM PUBLISHER]

Representative fossils of three extant lanternfish (Myctophidae) genera (Bolinichthys, Lampanyctus, andMyctophum) from the collections of Natural History Museum of Los Angeles County were identified, based on a combination of osteological and photophore characters. These specimens come from the upper Miocene Modelo Formation (Mohnian-Delmontian) of California, and represent the first skeletal records ofBolinichthys(otherwise identified as otoliths from the Late Miocene of Italy) andMyctophumbody fossils in North America, and confirm that both modern myctophid subfamilies exhibited a cosmopolitan distribution by the late Miocene. [ABSTRACT FROM PUBLISHER]

Investigation of trout (subf. Salmoninae) for their continuous osteological characters of head that included analyses of elements from skull and visceral (jaws, gills and gill covers) bones revealed the unambiguous distinction between the autochthonous and admixed brown trout Salmo trutta stocks of the Danube River drainage area in Serbia for the characters on vomer, skull height, pterotic and premaxilar bones. Rainbow trout Oncorhynchus mykiss and Ohrid Lake's belvica trout Salmo (Salmothymus) ohridanus were also examined as outgroup taxa in order to understand better the overall variability and to reduce bias in the methodology applied. Belvica trout were more similar to the admixed than to the autochthonous brown trout populations, especially concerning the characters on the bones of the skull. Rainbow trout appeared clearly distinct from all brown trout (autochthonous and admixed) on their elements of skull (its height and width at the sphenotic level), being similar to the autochthonous brown trout on the elements of visceral skeleton, whereas on the elements of visceral skeleton, belvica trout were the most distinct from the brown trout and the rainbow trout, mainly due to the difference in the length of the premaxilar and maxilar bones. [ABSTRACT FROM PUBLISHER]

Seasonal variations in the abundance of cyanobacteria and catch per unit effort (CPUE) of bluegill (Lepomis macrochirus) were investigated in Lake Biwa of Japan. High CPUE occurred from late spring to autumn when cyanobacteria dominated the community of photosynthetic plankton. However, the CPUE decreased substantially when the population density of cyanobacteria increased dramatically within an hour. Seasonal variation in the body weight of the fish with a fixed length was estimated from the length-weight relationships, revealing that body weight increased rapidly in early spring and reached its first peak in late spring, eventually decreasing in autumn after reaching the second peak. In May, bluegill fed on extremely large numbers of Bosmina longirostris when it dominated the zooplankton community. From June, the main diet of the bluegill became epiphytic filamentous green algae, which are the competitors for cyanobacteria. The biomass of submersed macrophytes in Lake Biwa has increased recently, potentially affecting cyanobacteria adversely since submersed macrophytes release allelochemicals and provide a habitat for cladocerans. However, propagation of submersed macrophytes also benefits bluegill, possibly contributing to the dominance of cyanobacteria by reducing the amounts of cladocerans and epiphytic algae. [ABSTRACT FROM AUTHOR]

The early Eocene great lakes of the Green River system preserved a rich fauna, allowing detailed study of the paleoecology of the area. Two genera, †Priscacara and †Mioplosus, are interesting because they are among the earliest well-known representatives of Percoidei sensu lato, and so offer a chance to explore the evolution of the North American fish fauna. A phylogenetic analysis including †Priscacara, †Mioplosus, and representatives of some 'basal' percoid families suggests that †Priscacara is a member of Moronidae, and that †Mioplosus has affinities with Lateolabrax, Siniperca, and Lates. †Priscacara is recovered as paraphyletic relative to the rest of Moronidae, primarily on the basis of meristic characters; in the absence of more robust evidence, both †P. serrata and †P. liops are retained within †Priscacara. The phylogenetic position of †Priscacara suggests a trans-Atlantic connection, because Moronidae contain genera from eastern North America and Europe. †Mioplosus is suggestive of an Asian link to the Eocene Green River system, due to its relationship with the Western Pacific Lateolabrax, the Asian Siniperca, and the African/Asian Lates. [ABSTRACT FROM AUTHOR]

The article provides information about the new softnose skate Brochiraja rajid genus from New Zealand waters. The group contains six species including Brochiraja asperula, B. spinifera and B. microspinifera. These species are closely related to members of the Indo-Pacific genus Notoraja and the presence of a bifurcated thorn on the mid-distal rostral cartilage that is strongly evident in juveniles and variably reduced in adults.

The complete mitochondrial genomes are sequenced in two individuals representing two morphological forms, ‘usual’ (U) and ‘gray’ (G), of the short-spined sea urchinStrongylocentrotus intermedius. The genome sequences are 15,705 bp in size, and the gene arrangement, composition, and size are very similar to the other sea urchin mitochondrial genomes published previously. A low level of sequence divergence (Dxy = 0.0083 ± 0.0007) is detected between the forms. The GenBank (KC490912) mt genome ofS. intermediusis much closer to the U form (Dxy = 0.0013 ± 0.0003) than to the G form (Dxy = 0.0085 ± 0.0006), demonstrating unique evolutionary trajectories for each form, which we previously suggested based on thebindingene and symbiont analyses. [ABSTRACT FROM PUBLISHER]