The distinctive isolated elements of Cynopodius, characterised by their deep narrow base and spatulate crown, were first described (as spine-like elements) by Ramsay Heatley Traquair in the late 19th Century, based on specimens from the Burghlee Ironstone (Serpukhovian, Carboniferous) at Loanhead near Edinburgh, Scotland. The type species Cynopodius crenulatus is also known from older Calciferous Sandstone Measures (Viséan) of Fife. Here we provide evidence that the elements are teeth rather than spines or dermal claspers, as hypothesised elsewhere. Thin sections of the teeth, illustrated for the first time, show osteodentine and tubate dentine forming the crown, covered by a thin outer hypermineralised layer on the cusps, and trabecular osteodentine or acellular bone forming the base. In recent decades, teeth of Cynopodius have also been collected from the lower Carboniferous Sainte Genevieve Formation (Mississippian: Viséan) of Iowa, Kentucky, and West Virginia in the USA. We assign these teeth from Iowa to Cynopodius robustus n. sp. They are distinguished from the type species by their relative robustness, with a ratio of maximum crown length to root length of c. 2:3 for C. traquairi and c. 1:2 for C. crenulatus, and lack of longitudinal curvature. The Scottish and American occurrences, though widely separated in the early Carboniferous, are the only known localities for the genus. The similarity between these over 300-million-year-old teeth and those of Recent long-toothed teleost reef fishes like Ctenochaetus, for instance, suggests that the Cynopodius animals might also have been specialised detritivores.

The cliff and foreshore sections at Blue Anchor Bay, north Somerset, provide a detailed picture of the transitional Triassic–Jurassic succession. The site has been recorded as a location for fossil fishes for over 200 years, and yet the assemblages from the bone beds have not been described. Here, we present new observations on the two bone beds and find major faunal differences: the classic basal bone bed at Blue Anchor Bay contains an assemblage dominated by osteichthyan teeth, unexpected because elsewhere the ichthyofauna is usually dominated by chondrichthyans. The upper bone bed at Blue Anchor Bay is indeed more typical, being dominated by teeth of hybodont chondrichthyans. We report two unusual finds, first five teeth of the rare shark Parasycylloides turnerae, only the fifth such record in the UK. Further, we report here for the first time a tooth of the pycnodontiform Eomesodon, the first report of this taxon from the Triassic of the UK or Europe. The two bone beds are distinguished not only by different assemblages, but also by evidence of different degrees of anoxia and water depth: the upper bone bed contains abundant pyrite and marcasite, indicating highly anoxic conditions, and perhaps deposition in deeper water than the basal bone bed.

Two species of deep-sea skates, Amblyraja frerichsi and Notoraja martinezi, are reported for the first time in Peruvian waters, representing the first record of their respective genera from the country. Earlier, A. frerichsi was known from both the southwestern Atlantic (off Brazil, Uruguay, and Argentina) and southeastern Pacific (off Chile), while N. martinezi was known from Costa Rica to Ecuador in the eastern-central and southeastern Pacific. This study contributes to the limited knowledge of deep-sea fish diversity along the South American west coast, and stresses the need of further taxonomic research in the region, particularly in light of the ecological importance of this group of fishes in marine ecosystems and its conservation state worldwide.

Chondrichthyan and actinopterygian fish remains from Rhaetian (c. 208.05–201.36 Ma) or perhaps Late Norian deposits in the Winterswijk quarry are described. The most abundant taxon is the actinopterygian Gyrolepis albertii, followed by the chondrichthyan Lissodus minimus. Furthermore, the palaeopterygian actinopterygians Saurichthys longidens and Birgeria acuminata, and some teeth of neopterygians Sargodon tomicus, ‘Lepidotes’ sp. and indeterminate pycnodontiforms are recorded in addition to the chondrichthyans Rhomphaiodon minor, Parascylloides turnerae and some ‘Hybodus’ cf. cuspidatus (senior synonym of H. cloacinus). Chondrichthyan dermal denticles, actinopterygian scales and gill rakers, tooth plates, and some fish bones were also found. There is considerable faunal resemblance to the various localities from the Rhaetian of the British Penarth Group, although it depends on the location as to whether chondrichthyans or actinopterygians prevail in the samples. On average, there are more chondrichthyan teeth present in the British samples than actinopterygian teeth, which is opposite to the situation in Winterswijk. That might be explained by different ecological circumstances, such as lower oxygen levels in bottom waters in Winterswijk and freshwater input and/or changes in salinity in the UK.

Permian fishes and their isolated microremains are known from many localities in the Zechstein Basin. However, up to date the vertebrates have never been revealed in the southeasternmost part of this ancient sea. The new material consists of euselachian-type dermal denticles,?Listracanthus sp. dermal denticle,?Omanoselache sp. tooth, actinopterygian scales and actinopterygian teeth. Here, the detailed study of euselachian and actinopterygian remains, their stratigraphic distribution and geographical contexts is presented. Based on the qualitative analysis of teeth shapes several ecomorphotypes were described as well as the probable dietary preferences of fishes were reconstructed. These finds confirmed existence of small predators who fed on soft bodied prey as well as durophagous forms which were feeding on small shelly crustaceans or molluscs. The analysis of stratigraphic distribution of microremains, and their comparison with neighbouring sections revealed a spatially correlatable trend in increasing abundance of fishes in the more clayey parts of sections, interpreted to be positively associated with a sea level transgression event.

The ichthyofauna of the Atlantic and Pacific coasts off the American continent is very rich. Consequently, a high biodiversity of nematodes parasitizing these vertebrates is also expected. Currently, data on nematode parasites of marine fish off the Americas are fragmented. A review of all adult nematode species reported parasitizing marine fish from off the American continent is herein presented, as well as comments on their patterns of diversity, life cycles and advances in the taxonomic and phylogenetic knowledge. A total of 209 valid species, 19 species inquirendae and 6 dubious records have been recorded, the majority from the fish taxa Eupercaria and Perciformes. The families Sciaenidae, Serranidae and Lutjanidae, as well as the tropical and temperate Atlantic waters, exhibited the highest records of parasitic nematodes. The Cucullanidae, Philometridae and Cystidicolidae were the most speciose families of nematodes, which may be related to technological advances and relatively recent efforts of taxonomists, resulting in description of new taxa and the resolution of taxonomic problems. Numerous taxonomic questions still need resolution and, even though genetic data have been important for this process, the database is very scarce. This is the first review on all currently known nematode species parasitizing marine fish off the Americas and may serve as an important basis of reference for future approaches on these organisms.

Tristychius arcuatus, from the late Viséan of Scotland, is known from numerous ironstone nodule-encased specimens. These are reinvestigated using computerised tomography (CT) scanning and 3-D digital reconstruction methods. CT scans of the neurocranium (braincase) corroborate many features of the existing reconstruction, but also reveal new details of the gross proportions, the external morphology and, for the first time, features of the internal morphology, including the otic skeletal labyrinth. The unusual position of the articulation for the palatoquadrate on the ventral surface of the postorbital process is confirmed, but the area for the hyoid articulation is relocated posteriorly and the configuration of nerve foramina within the orbit is changed. A preliminary phylogenetic hypothesis is offered, suggesting a place for Tristychius within a sequence of early branching events in the elasmobranch lineage. In this, Tristychius is not resolved as a hybodontid, but is instead a stem elasmobranch possibly related to genera such as Acronemus, and exemplifying anatomical conditions close to the base of the Euselachii. As such, the neurocranium of Tristychius offers important insight into a defining feature of these early members of the anatomically advanced elasmobranchs: the origin of specialised phonoreception.

Chondrenchelys problematica, from the Viséan (Holkerian) of Scotland, is the earliest holocephalan known from extensive cranial and postcranial material. Here, we provide a comprehensive new description of this taxon using three new specimens, in which we observe many morphological features for the first time. Much of the cranial morphology is closer to that of living chimaeroid holocephalans than was previously appreciated. For this reason, we provide original figures illustrating the chondrocranium of a hatchling Callorhinchus milii demonstrating these similarities. In Chondrenchelys, although the jaw articulation is positioned at the posterior margin of the orbit, the high-walled lamina orbitonasalis and densely-mineralised antorbital crest provide evidence for forward rotation of the jaw adductor musculature. Preserved foramina for the efferent superficial ophthalmic nerves show that the sensory organs on the rostrum were enervated in a manner similar to modern sharks, with the ophthalmic nerves not enclosed in an ethmoid canal, as in modern holocephalans. The conjunction of numerous distinctly holocephalan features with those that are otherwise general to Chondrichthyes demonstrates a decoupling of several of the structural conditions that characterise the distinctive morphological complex of the extant holocephalan skull. The anguiliform postcranium is more elongate than previously reconstructed, and it is now clear that the axial skeleton extended beyond the posterior extremity of the elongate dorsal fin. Morphological characters are reviewed with a view to further phylogenetic analyses. We recommend using the appearance of Chondrenchelys at 336.5 Ma as a hard minimum age for the last common ancestor of elasmobranchs and chimaeroids, because of its secure association with other holocephalans, and current uncertainties concerning elasmobranch stem lineage membership.

On 19 April 2014, a female goblin shark, Mitsukurina owstoni, was captured in a commercial shrimp trawl in the northern Gulf of Mexico. The shark, estimated to be approximately 5 m in length, was captured at a depth of approximately 490 m and released alive shortly after capture. This specimen represents the second goblin shark ever recorded in the Gulf of Mexico.

This paper reports the first record of the narrowmouth catshark Schroederichthys bivius from the coast of Paraná State, southern Brazil, increasing its distribution along the Brazilian coast.

Observations, photographs, and video footage of a 337 cm total length female smalltooth sand tiger shark, Odontaspis ferox made at a depth of 348 m on the northern slope of San Ambrosio Island in the Desventuradas Islands (26°19.456′S 79°52.281′W) on 25 February 2013 represent not just the first record of this species in Chilean waters, but the first in the entire south-eastern Pacific Ocean, marking a tremendous range extension of this species. We also summarize the few known occurrences of this species along the Pacific and Atlantic coasts of South America.

An association of diverse hollow spines and dermal denticles (ichthyoliths) from the Carboniferous (Westphalian) of Todmorden, Yorkshire, England are attributed to a new genus of enigmatic shark that may lie close to Listracanthus Newberry & Worthen, 1870. Scanning electron microscopy shows that denticle morphology is highly variable, but forms a morphocline including elongate multi-spined elements as well as robust dome-like stellate denticles and recurved spinose elements. Histological analysis suggests an absence of enameloid. Continuous variation of form between elongate multi-cusped spines to boss-like circular denticles shows that all previously described Palaeozoic species of Listracanthus are probably junior synonyms of the type species L. hystrix Newberry & Worthen, 1870. The status of Listracanthus as a surviving ‘Lilliputian’ taxon after the Permian extinction is questioned. Although the new specimen has affinities with Listracanthus, significant differences in the form of the posterior spines on elongate denticles warrants its placement in the new genus Acanthorhachis gen. nov. The family Listracanthidae is erected to accommodate Listracanthus and Acanthorhachis.

The feeding habits of the pelagic stingray (Pteroplatytrygon violacea) were studied using 84 stomachs of specimens caught in the northern Adriatic Sea in the period from April 2004 to October 2005. Percentage of empty stomachs found was overall very low, being a bit bigger in smaller specimens. The diet consisted of two main taxonomic groups such as teleost fish and cephalopods, but few specimens of crustaceans were recorded as well. The main food item was represented by anchovy, while cuttlefish and red band fish represented the alternative preys. Prey size was positively correlated with the size of predator. The proportion of anchovies in the diet grew with size of predator, while the one for red band fish decreased. The stingray was confirmed to be a top predator of pelagic fish species, although the presence of benthic prey shows that it feeds also at the bottom.

Information on morphological abnormalities in the cephalic region of three female blue sharks' (Prionace glauca) foetuses found in Baja California Sur, Mexico, is included. In one foetus with bicephaly, the liver was shared. In the other two foetuses they do not have eyes, and part of their snout was not well-developed, with malformations in cranial cartilage and gill slits. A possible explanation for these deformities in blue shark embryos is that the blue shark is the most fecund shark worldwide with the highest number of embryos produced and not all embryos can be developed in their small uteri.

Habitat use of Manta alfredi and M. birostris was assessed at 20 localities in the Indian and Pacific Oceans based upon 3328 photographic observations. Geographical relationships of the two species were scored as either microallopatry, microparapatry or microsympatry at each locality. Our study revealed a mosaic habitat occupancy by the two species within their macrosympatric range.

Argentina is one of the countries with the largest overall landings of skates and rays(24 000 t/year). As a consequence of high levels of exploitation and deficient managementtools, many of these species are threatened with extinction. In the bottom trawl fisheryof San Matías Gulf, northern Patagonia, skates and rays are caught as bycatch and all havehistorically been recorded in the fishery logbook under the category “rays”. Therefore,species composition and their characteristics were unknown. The aim of this study was tocharacterize the commercial exploitation of batoid species in this fishery. Our resultsindicate that commercial landings include nine species of skate, six of which are common.Among these, Atlantoraja platana, Sympterygia bonapartiiand Dipturus chilensis were considered the main species of thisfishery. Their combined relative abundance and weight made up about 90% of the batoidcatch throughout the year. Sexual segregation was detected in four species in whichindividuals of one sex dominated commercial landings. The commercial fraction was composedof individuals with a wide range of sizes. Immature individuals could represent 90% of theindividuals landed for some species. At present, lack of data prevents us from quantifyingthe impact that this fishery is having on these species, but our findings highlight theimportance of conducting research surveys to assess the abundance and geographic extent ofthese populations. The information presented here provided the basis for the proposal of anew logbook format incorporating species-level identification. The new logbook wasimplemented on 1 January 2010.

The sandpaper skate, Bathyraja kincaidii, is one of four skate species commonly taken in trawl fisheries off central California although very little is known about its life history. In this study, age and growth were evaluated from 187 vertebrae using a common growth band counting method. An attempt to use marginal increment analysis and centrum edge analysis failed to validate the annual periodicity of growth band formation; however, it is a valid assumption based on structural similarity from other studies. Assuming annual band formation, von Bertalanffy growth parameters were determined for females (L∞ = 537.3 mm; k = 0.237; to = –1.629; N = 99) and males (L∞ = 580.2 mm; k = 0.185; to = –2.530; N = 88). Maximum likelihood ratios indicated no significant difference (P > 0.05) between male and female von Bertalanffy growth parameters, thus data were combined (L∞ = 557.8 mm; k = 0.207; to = –2.147; N = 187). Age estimates from band counts in vertebral centra indicated a minimum longevity of 17 and 18 years for female and male B. kincaidii, respectively. Caudal thorns were also assessed for age analyses, but were deemed unreliable and could not be used to verify age estimates from vertebral centra.

As global fishing effort increasingly expands into deeper water, concerns exist over the ability of deep-sea fishes to sustain fisheries. There is however little quantitative evidence to support these concerns for the deep-sea cartilaginous fishes (Chondrichthyes: sharks, rays and chimaeras). This paper compiled available life history data for this group to analyse their ability to rebound from population declines relative to continental shelf and pelagic species. Deep-sea cartilaginous fishes have rates of population increase that are on average less than half those of shelf and pelagic species, and include the lowest levels observed to date. Population doubling times indicate that once a stock has been depleted, it will take decades, and potentially centuries, before it will recover. Furthermore, population recovery rates decrease with increasing depth, suggesting species that occur deepest are those most vulnerable to fishing. These results provide the first assessment of the productivity of deep-sea chondrichthyans, highlighting that precautionary management of developing deep-sea fisheries is essential if stocks and biodiversity are to be maintained.

The present study provides a check list of elasmobranchs from the Paraná State coast, southern Brazil. Information from fish collections, literature data, field surveys and personal communications were included. Results indicated that 83 species from seven orders and 28 families were recorded. According to the results 51 species belonging to six orders and 17 families of sharks; and 32 species belonging to one order and eleven families of rays occur in this region. The most species-rich families were Carcharhinidae (14 species) and Arhynchobatidae (eight species).

The first case of albinism in the kitefin shark, Dalatias licha, is reported here through the study of one specimen caught by professional bottom trawl in the Gulf of Genoa, Ligurian Sea. The albino surface was quantified and morphometric and meristic characteristics were compared with those of normal specimens of the same sex and equivalent length, caught within the same area. The shark body presented a partial reduction in pigmentation and no morphometric differences between the albino specimen and the normal individuals were observed.