Search

Myxozoa represent a diverse group of microscopic cnidarian endoparasites alternating between invertebrate and vertebrate hosts. Of the approximately 2,600 species described predominantly from teleost fish, only 1.8% have been reported from cartilaginous fishes (Elasmobranchii). As ancestral vertebrate hosts of myxozoans, elasmobranchs may have played an important role in myxozoan evolution, however, they are also some of the largest vertebrate hosts known for this group of parasites. We screened 50 elasmobranchs belonging to nine species and seven families, from various geographical areas, for myxozoan infection. We found a 22% overall prevalence of myxozoans in elasmobranchs and describe five species new to science. We investigated, for the first known time, the evolution of spore size within three phylogenetic clades, Ceratomyxa, Sphaerospora sensu stricto and Parvicapsula. We found that spores from elasmobranch-infecting myxozoans were on average 4.8× (Ceratomyxa), 2.2× (Parvicapsula clade) and 1.8× (Sphaerospora sensu stricto except polysporoplasmic Sphaerospora spp.) larger than those from teleosts. In all analysed clades, spore size was correlated with phylogenetic position. In ceratomyxids, it was further strongly positively correlated with fish body size and habitat depth, independent of cellular composition of the spores and phylogenetic position in the tree. While in macroparasites a host size-correlated increase in parasite size occurs on a large scale and is often related to improved exploitation of host resources, in microscopic parasites size ranges vary at the scale of a few micrometres, disproportionate to the available additional space in a large host. We discuss the ecological role of these changes with regard to transmission under high pressure and an invertebrate fauna that is adapted to deeper marine habitats.

Management and conservation actions in marine-protected areas require baselines for monitoring threatened marine fauna such as elasmobranchs. This article provides evidence of the occurrence of 34 species of elasmobranchs (21 sharks and 13 batoids) in the Malpelo Flora and Fauna Sanctuary, Colombia, including five new records of sharks and three of rays. From 1987 to 2021, new records were obtained by underwater visual census using SCUBA, manned submersibles and deep-ocean cameras to depths of up to 2211 m. Of the recorded species, 21 are considered as threatened taxa (64%) by the IUCN, making the Malpelo Flora and Fauna Sanctuary an essential conservation area for this highly threatened group of species.

BackgroundSharks and rays are some of the most threatened marine taxa due to the high levels of bycatch and significant demand for meat and fin-related products in many Asian communities. At least 25% of shark and ray species are considered to be threatened with extinction. In particular, the density of reef sharks in the Pacific has declined to 3–10% of pre-human levels. Elasmobranchs are thought to be sparse in highly urbanised and turbid environments. Low visibility coupled with the highly elusive behaviour of sharks and rays pose a challenge to diversity estimation and biomonitoring efforts as sightings are limited to chance encounters or from carcasses ensnared in nets. Here we utilised an eDNA metabarcoding approach to enhance the precision of elasmobranch diversity estimates in urbanised marine environments.ResultsWe applied eDNA metabarcoding on seawater samples to detect elasmobranch species in the hyper-urbanised waters off Singapore. Two genes—vertebrate 12S and elasmobranch COI—were targeted and amplicons subjected to Illumina high-throughput sequencing. With a total of 84 water samples collected from nine localities, we found 47 shark and ray molecular operational taxonomic units, of which 16 had species-level identities. When data were compared against historical collections and contemporary sightings, eDNA detected 14 locally known species as well as two potential new records.ConclusionsLocal elasmobranch richness uncovered by eDNA is greater than the seven species sighted over the last two decades, thereby reducing phantom diversity. Our findings demonstrate that eDNA metabarcoding is effective in detecting shark and ray species despite the challenges posed by the physical environment, granting a more consistent approach to monitor these highly elusive and threatened species.

We present comparative analysis of the micro- and macro-morphology of the olfactory organ of six neoselachians living in different habitats: two freshwater benthopelagic batoids, Potamotrygon motoro and Potamotrygon hystrix (Potamotrygonidae) as well as four species of sharks occupying the outer continental shelves and upper slopes Mustelus mustelus (Trikidae) and Scyliorhinus canicula (Scyliorhinidae), and deep-water Galeus melastomus (Scyliorhinidae) and Etmopterus spinax (Etmopteridae). Our research used light and electron (TEM, SEM) microscopes as well as macroscopic observations. The position of the nostrils in relation to the mouth varied in these species but all of them possessed elongate olfactory rosettes with primary lamellae arranged over two rows. The types of primary lamellae were distinguished based on their arrangement on the opposite sides of the median raphe as well as morphology of secondary lamellae and distribution of sensory and non-sensory regions of olfactory epithelium lining the lamellae; these were different between batoids and sharks. Analysis of olfactory epithelium revealed the presence of microvillous olfactory sensory neurons as the only type of receptor cells in all studied species whereas ionocytes were recognized only in sharks. All species possessed one type of goblet cells (Alcian Blue or Periodic Acid Schiff positives) except for P. motoro in which both types of goblet cells were present. Moreover, apical parts of non-sensory microvillous cells that lined the basal parts of the primary lamellae, possessed PAS-positive mucous granules; these were present in both species of batoids. This analogous region was abundant in goblet cells in the species of sharks studied here. Results indicated that differences between freshwater and marine species as well as between marine species occupying various habitat zones include mainly nostrils position, density of occurrence of ionocytes and goblet cells within olfactory epithelium as well as biochemical character of mucus.

The similarity at the genus-level was estimated between 23 Cenomanian elasmobranch assemblages from different regions of the world (Volga Region, Mangyshlak, Anglo-Paris basin, Lithuania, northwestern Germany, southwestern France, northern Spain, North America, Venezuela, Lebanon, Egypt, Algeria, Nigeria, Angola, India, Australia) using the Jaccard similarity coefficient. From cluster analysis and a paleogeographic map, hypotheses were made about possible relationships between coeval elasmobranch assemblages and the paleogeographic factors that influence them. Five faunistic clusters were identified: European, Atlantic, South Tethyan, Indian, Australian. The clustering was found to depend on the configuration of water bodies and land masses, and on the temperature regime. The impact of paleobathymetry is less clear, although it is appreciable in the clustering within the groups themselves.

Malformations are common in trilobites, but the majority of described specimens are from Europe and North America. Only a few abnormal trilobites have been reported from China. Ten abnormal trilobites from Cambrian, Ordovician and Silurian strata in central and eastern China are documented. The abnormal Ordovician trilobites are found for the first time in China. All malformations occur in the thoraxes and pygidia, and were caused by a sub-lethal predatory attack, genetic or embryological malfunction, or injury sustained during molting. It is difficult to identify the predators of the six injured trilobites, but potential predators include Cambrian non-trilobite arthropods, Ordovician cephalopods, and Silurian eurypterids, chondrichthyes or cephalopods, even cannibalistic trilobites. Abnormal specimens caused by sub-lethal predatory attacks mainly occur in Cambrian strata in China and other areas in the world, and are very rare in post-Cambrian strata. This pattern may reflect the rise of predators and increased predation in the post-Cambrian, which led to an increased trilobite fatality rate, thus reducing the probability that injured specimens would become fossilized.

Cartilaginous fish, or Chondrichthyes, are the oldest extant vertebrates to possess the MHC and the Ig superfamily–based Ag receptors, the defining genes of the gnathostome adaptive immune system. In this work, we have identified a novel MHC lineage, UEA, a complex multigene nonclassical class I family found in sharks (division Selachii) but not detected in chimaeras (subclass Holocephali) or rays (division Batoidea). This new lineage is distantly related to the previously reported nonclassical class I lineage UCA, which appears to be present only in dogfish sharks (order Squaliformes). UEA lacks conservation of the nine invariant residues in the peptide (ligand)–binding regions (PBR) that bind to the N and C termini of bound peptide in most vertebrate classical class I proteins, which are replaced by relatively hydrophobic residues compared with the classical UAA. In fact, UEA and UCA proteins have the most hydrophobic-predicted PBR of all identified chondrichthyan class I molecules. UEA genes detected in the whale shark and bamboo shark genome projects are MHC linked. Consistent with UEA comprising a very large gene family, we detected weak expression in different tissues of the nurse shark via Northern blotting and RNA sequencing. UEA genes fall into three sublineages with unique characteristics in the PBR. UEA shares structural and genetic features with certain nonclassical class I genes in other vertebrates, such as the highly complex XNC nonclassical class I genes in Xenopus, and we anticipate that each shark gene, or at least each sublineage, will have a unique function, perhaps in bacterial defense.

The silky shark Carcharhinus falciformis is considered one of the least productive pelagic shark species. The estimation of growth and demographic parameters presented here is fundamental to a sound knowledge of population status of the species in the Atlantic Ocean. Data was collected through an onboard observer program of the Brazilian chartered pelagic longline fishing fleet that operates in the Equatorial Southwestern Atlantic. Vertebral analysis produced the von Bertalanffy growth parameters for pooled sexes L∞ = 283.05 cm; k = 0.0987 yr-1 and t0 = -3.47 yr. Males reached sexual maturity at 8.6 yr and females at 9.9 yr. Longevity was estimated at 27.2 yr. Age structure analysis indicated that 80.5% of the catch was composed of juveniles, with recruitment to the fishery from the first year of life (age 1+). These biological parameters are responsible for the species’ low resistance to fishing pressure, and our demographic analysis (Leslie Matrix) shows an annual population decline of 12.7% yr-1 under the current fishing scenario for the period analyzed. Therefore, conservation measures must be enacted to reestablish the population of silky sharks to safe levels for the maintenance of this species in the South Atlantic.

A young individual of Isurus oxyrinchus was caught by a commercial longline off Dana Island (Mersin Bay, northeastern Mediterranean Sea) at a depth of 72 m on May 18th 2020. Morphometric measurements of the specimen were recorded and its photographs were taken. The examined specimen is now being preserved in the Museum of Systematics at Faculty of Fisheries of Mersin University, under the reference number MEUFC-20-11-132. This occurrence of a young female specimen reported in this study is adding a new location (Mersin Bay) from the Mediterranean's Turkish waters.

The bigeye thresher shark Alopias supeciliosus is a large epipelagic and mesopelagic species, and it has a wide distribution in the Atlantic. However, its record in the Gulf of Mexico is sporadic. A single adult female of A. superciliosus, measuring 360 cm total length and about weight 165 kg, was caught by artisanal fishers in Salinas Roca Partida, Veracruz, Mexico, on July 14, 2020. This study reports the first occurrence of this species in the southwestern of the Gulf of Mexico, which extends its geographical distribution in Mexico.

This paper reports the occurrence of two stingray species from Andaman waters, India; the zonetail butterfly ray Gymnura zonura (Bleeker, 1852) (695 mm DW) which represents a new distributional range, and the mangrove stingray Urogymnus granulatus (Macleay 1883) (395 mm DW) which represents a rare occurrence. These occurrences suggest hidden stingray diversity in this region. Morphological descriptions of both species, as well as a molecular barcode of G. zonura, were generated in the present study to clarify the taxonomic information. The current report assists in improving the understanding of the local diversity and distribution of batoids in Andaman waters, which is crucial for developing fishery management strategies.

Chimaera compacta sp. nov., a new species of shortnose chimaera (Holocephali: Chimaeriformes: Chimaeridae), is described from a single specimen collected at 595–655 m depth, off Amsterdam Island, in the southern Indian Ocean. The species is easily distinguished from its congeners by the combination of the following characters: massive head with short snout; stocky and relatively long trunk 44% BDL, short tail with second dorsal fin base 72% BDL; long pelvic fin anterior margin 26% BDL. Caudal fin dorsal origin slightly posterior to caudal fin ventral origin. Firm, non-deciduous skin; brown color with yellow blotches. Chimaera compacta sp. nov. is morphologically close to Chimaera lignaria Didier 2002 from New Zealand and Chimaera willwatchi Clerkin, Ebert and Kemper 2017 from south western Indian Ocean. The new species can be distinguished from other Chimaera species based on DNA sequences divergence of the COI and NADH2 genes. This species has a nucleotide sequence divergence (uncorrected p distances) for the studied genes of 4.2 and 4.1%, respectively, with its closest relatives. Phylogenetically, Chimaera compacta sp. nov. is nested within a well-supported group including Chimaera carophila Kemper, Ebert, Naylor and Didier 2014, Chimaera didierae Clerkin, Ebert and Kemper 2017, C. lignaria, Chimaera macrospina Didier, Last and White 2008, Chimaera notafricana Kemper, Ebert, Compagno and Didier 2010, Chimaera opalescens Luchetti, Iglesias and Sellos 2011, and C. willwatchi. It is the first Chimaeridae described for the Territory of the French Southern and Antarctic Lands.

We report here a diverse assemblage of sharks and batoids representing the genera Carcharhinus, Rhizoprionodon, Galeocerdo, Sphyrna, Myliobatis, Aetobatus, Dasyatis, Pastinachus, Himantura and Pris...

The definition and scope of the genus Carcharhinus has undergone several changes over the years and recent molecular studies have questioned its monophyly by the inclusion of other carcharhinid genera. Although many descriptions of chondrocranium are available for Carcharhinus species, some inconsistences and divergences are found in the literature, mainly regarding the foramina of the orbital region. In this study, the chondrocranium of the silky shark, Carcharhinus falciformis, from specimens caught at the Brazilian coast and the terminology of its components is revised has been described. Chondrocrania of other Carcharhinus species and carcharhinid genera are also examined in order to investigate the phylogenetic significance of chondrocranial morphology. Three new anatomical terms and nine chondrocrania characters are proposed and described in detail. The chondrocranial morphology varies widely among Carcharhinus species mainly regarding the rostrum and nasal capsules. The chondrocrania of Prionace, Nasolamia, and Negaprion are similar to Carcharhinus species and reveal the need to further explore the relationships among these genera. Characters potentially informative for systematics are the shape of rostral node, the preorbital process, and the subethmoidal fossa, and the occurrence of an epiphyseal notch and foramen, and must be included in phylogenetic studies encompassing other carcharhiniforms.

Elasmobranchs in the Gulf of California have been found with malformations, probably originated during embryonic development or caused by environmental anomalies and pollution associated with intense mining activity in the region. Clasper malformations are reported for the first time in two specimens of Pseudobatos buthi, a species recently described from the Gulf of California. The function of the claspers was not affected by the size difference, because specimens presented the distinctive characteristics of an adult individual. The reproductive system did not show any malformation, with symmetrical testes. Histological analysis of the testes revealed a normal spermatogenic development. To elucidate the causes and to detect a possible effect of the morphological malformations due to high levels of heavy metals, trace concentration values (cadmium, copper, iron, manganese, silver, lead and zinc) were determined in muscle and liver. Cadmium and lead concentrations in the muscle of the two specimens were below the permissible limit for human consumption (−1); however, iron and zinc presented high values (0.455, 4.024 mg kg−1 in muscle and 21.931, 3.694 mg kg−1 in liver respectively). Mining activity and heavy metal pollution in the sampling area may have caused the malformations, which might be attributed to the high values of iron and zinc discovered in the muscle and liver.

Persistent organic pollutants (POPs) were determined in Gymnura altavela liver samples from one of the most impacted estuarine environments in the Atlantic Ocean (Guanabara Bay, Brazil). PCBs were the predominant compounds (91.2%) averaging 6773 ± 4659 ng.g−1 lipid weight (lw). DDT, Mirex, HCH and HCB concentrations were 633 ± 715, 6.2 ± 9.3, 3.4 ± 1.4 and 0.5 ± 0.5 ng.g−1 lw, respectively. Recent DDT input in the estuary was minimum, as verified by the p,p′-DDE/∑DDT ratio (0.67). The prevalence of industrial compounds was highlighted by the ΣDDT/ΣPCB ratio (0.08). A negative correlation detected between disc width and PCBs, Mirex and HCH concentrations may be a consequence of maternal offloading. High POP concentrations in G. altavela liver samples from Guanabara Bay suggests that PCBs, in particular, may pressure the conservation of this threatened with extinction tropical estuarine batoid species.

Urotrygon chilensis (Gunther, 1872) was described based on a single specimen acquired by the British Museum of Natural History, London, from the Johan Cesar Godeffroy Museum in Hamburg. This medium...

Sturgeons and paddlefishes (Acipenseriformes) occupy the basal position of ray-finned fishes, although they have cartilaginous skeletons as in Chondrichthyes. This evolutionary status and their morphological specializations make them a research focus, but their complex genomes (polyploidy and the presence of microchromosomes) bring obstacles and challenges to molecular studies. Here, we generated the first high-quality genome assembly of the American paddlefish (Polyodon spathula) at a chromosome level. Comparative genomic analyses revealed a recent species-specific whole-genome duplication event, and extensive chromosomal changes, including head-to-head fusions of pairs of intact, large ancestral chromosomes within the paddlefish. We also provide an overview of the paddlefish SCPP (secretory calcium-binding phosphoprotein) repertoire that is responsible for tissue mineralization, demonstrating that the earliest flourishing of SCPP members occurred at least before the split between Acipenseriformes and teleosts. In summary, this genome assembly provides a genetic resource for understanding chromosomal evolution in polyploid nonteleost fishes and bone mineralization in early vertebrates.

Although skeletal and muscle anatomy has supported Gymnuridae as the sister group of the most derived myliobatoids, recent studies based on molecular characters suggest that the family branches into a more basal position than previously thought. This study aims to understand the brain anatomy of the genus Gymnura and its importance in the evolution of the batoid brain. The brain anatomy of Gymnura lessae and Gymnura marmorata is relatively simple. They exhibit a small brain and telencephalon (T), where the latter is wider than it is longer, and the division of the posterior central nucleus is poorly developed. The cerebellum (C) is symmetrical and is not highly foliated. Unlike other species, the brain auricles are smooth, and the posterior auricles exhibit a diagonal arrangement, not always forming a bridge over the fourth ventricle. These auricles are larger in G. marmorata. A principal component analysis based on 20 morphological variables, revealed a separation between species, and multivariate analysis of variance identified significant differences. The most important variables in species segregation were a deeper olfactory bulb in G. lessae and a greater distance between the bulbs in G. marmorata. Contrary to the body anatomy, the brain anatomy reveals that Gymnura has a simpler and more primitive brain than most derived myliobatoids. Our results are consistent with the evidence from phylogenies developed with molecular data, where gymnurids are a basal group within myliobatoids.

Extinct lamniform sharks (Elasmobranchii: Lamniformes) are well represented in the late Mesozoic‒Cenozoic fossil record, yet their biology is poorly understood because they are mostly represented o...

The visual sense of elasmobranch fishes is poorly studied compared to their bony cousins, the teleosts. Nevertheless, the elasmobranch eye features numerous specialisations that have no doubt facilitated the diversification and evolutionary success of this fascinating taxon. In this review, I highlight recent discoveries on the nature and phylogenetic distribution of visual pigments in sharks and rays. Whereas most rays appear to be cone dichromats, all sharks studied to date are cone monochromats and, as a group, have likely abandoned colour vision on multiple occasions. This situation in sharks mirrors that seen in other large marine predators, the pinnipeds and cetaceans, which leads us to reassess the costs and benefits of multiple cone pigments and wavelength discrimination in the marine environment.

Nine specimens (one female and eight males, all juveniles) of lesser devil ray, Mobula hypostoma (Bancroft, 1831), were caught in the southwest Gulf of Mexico. These specimens represent the first record of the species in the Mexican waters. The disk width ranged between 552 and 773 mm. Morphometrics data are consistent with previously published records. Because of the number of specimens captured, we suggest that it is not a rare species in the southwest Gulf of Mexico.

The Revillagigedo Archipelago National Park is the largest no-take Marine Protected Area in North America and it is essential for the conservation of globally endangered marine megafauna, including cetaceans, sea birds and cartilaginous fishes. The present paper reports the occurrence of 28 chondrichthyan species, including 19 sharks, seven batoids and two chimaeras in the Revillagigedo Archipelago, comprising eight new records and a brief revision of confirmed species to date.

This study reports the first records of cowsharks (Hexanchidae) in the Galapagos Islands, in particular Notorynchus cepedianus and Hexanchus griseus, observed between depths of 210 and 418 m on footage from free-falling autonomous deep-ocean cameras. These sightings provide new information on the habitat preferences and range distribution for N. cepedianus and the first records of H. griseus in Ecuadorian waters. The findings support the formulation of regional conservation strategies for these large apex predator species and highlight the limited biological knowledge of Galapagos' deep-water ecosystems.

The validity of the chondrichthyan species Petalodus ohioensis Safford 1853, has long been in doubt due to the poor quality of the published figures and the unknown whereabouts of the holotype. That situation changed with the discovery of casts of the holotype in the collections of the Yale Peabody Museum of Natural History. The quality of the casts is poor, but sufficient to establish P. ohioensis as a valid species and as a senior synonym of P. alleghaniensis Leidy 1856. Recently, casts of the holotype of much better quality were found in the collections of the Field Museum of Natural History, accompanied by documentation indicating that they were likely obtained directly from Safford by O.P. Hay in 1896. The Field Museum casts clearly show the bands of ridges at the base of the crown on the labial and lingual sides, which are not visible on the Yale Peabody Museum casts.

Mennerotodus Zhelezko, 1994, is an extinct lamniform shark known to occur in Paleogene strata of the Tethyan region of Asia and Europe. Although only a single species has been named, multiple subspecies have been erected and used as biostratigraphic tools in Asia. The genus has not been reported with confidence outside of the Tethyan region, but we have identified two new species of Mennerotodus from Paleogene deposits of the southeastern United States. Mennerotodus mackayi sp. nov. is described by teeth occurring in the lower Paleocene (Danian Stage) Pine Barren Member of the Clayton Formation of southern Alabama. A middle Eocene (Bartonian) species, Mennerotodus parmleyi sp. nov., is based on material occurring in the Clinchfield Formation in central Georgia. The early Paleocene record could indicate a North American origin for Mennerotodus relatively soon after the K–Pg event, with subsequent radiation to other parts of the world. The genus is likely more widely distributed than is currently known, but teeth can easily be overlooked due to their similarity to other taxa.

When describing the architecture and ultrastructure of animal skeletons, introductory biology, anatomy and histology textbooks typically focus on the few bone and cartilage types prevalent in humans. In reality, cartilage and bone are far more diverse in the animal kingdom, particularly within fishes (Chondrichthyes and Actinopterygii), where cartilage and bone types are characterized by features that are anomalous or even pathological in human skeletons. This review discusses the curious and complex architectures of shark and ray tessellated cartilage, highlighting similarities and differences with their mammalian skeletal tissue counterparts. By synthesizing older anatomical literature with recent high-resolution structural and materials characterization work, this review frames emerging pictures of form-function relationships in this tissue and of the evolution and true diversity of cartilage and bone.

The Holocephali is a major group of chondrichthyan fishes, the sister taxon to the sharks and rays (Elasmobranchii). However, the dentition of extant holocephalans is very different from that of the elasmobranchs, lacking individual tooth renewal, but comprising dental plates made entirely of self-renewing dentine. This renewal of all tissues occurs at the postero-lingual plate surface, as a function of their statodont condition. The fossil record of the holocephalans illuminates multiple different trends in the dentition, including shark-like teeth through to those with dentitions completely lacking individual teeth. Different taxa illustrate developmental retention of teeth but with fusion in their serial development. Dentine of different varieties comprises these teeth and composite dental plates, whose histology includes vascularized tubes within coronal dentine, merging with basal trabecular dentine. In this coronal vascularized dentine, extensive hypermineralization forms a wear resistant tissue transformed into a variety of morphologies. Through evolution, hypermineralized dentine becomes enclosed within the trabecular dentine, and specialized by reduction into specific zones within a composite dental plate, with these increasing in morphological disparity, all reflecting loss of defined teeth but retention of dentine production from the inherited developmental package.

On 25 December 2012, a specimen of Prionace glauca (Linnaeus, 1758) was caught by a swordfish longliner along with 9 swordfish together off Fethiye at a depth of 1200 m. The specimen caught was measured as TL and weighed (kg), and photographed. The specimen was 85 cm TL and 7 kg. According to the previous studies, blue sharks especially observed abundantly in northern Aegean Sea, and can be accepted very rare incidental catch from the Turkish coasts owing to weak presuppose of swordfish fishery. However, there is an important place of blue sharks in the global fin trade area. Therefore, population trend of this shark species is swift decreasing.

In a seminal study on elasmobranch systematics, Maisey proposed the monophyly of a large lineage of sharks based primarily on the sharing of an orbitostylic jaw suspension. This group was later redefined as the Squalomorphi, which included Squatinidae but not Batoidea. Subsequent morphological analyses, however, rejected Maisey’s scheme, which was left aside for nearly two decades until the first molecular phylogenies began to cluster again the orbitostylic sharks into a monophyletic group. In a broad comparative investigation of the anatomy of the appendicular skeleton of cartilaginous fishes, we discovered new evidence supporting the monophyly of squalomorph sharks: the presence of a posterior process at the lateral region of the coracoid bar serving as a origin site for the depressor pectoralis II muscle. This feature would be the first strong morphological evidence in 40 years potentially supporting the monophyly of Squalomorphi.

The genus Scyliorhinus is part of the family Scyliorhinidae, the most diverse family of sharks and of the subfamily Scyliorhininae along with Cephaloscyllium and Poroderma. This study reviews the phylogenetic relationships of species of Scyliorhinus in the subfamily Scyliorhininae. Specimens of all Scyliorhinus species were examined as well as specimens of four of the 18 species of Cephaloscyllium, two species of Poroderma, representatives of almost all other catshark (scyliorhinid) genera and one proscylliid (Proscyllium habereri). A detailed morphological study, including external and internal morphology, morphometry and meristic data, was performed. From this study, a total of 84 morphological characters were compiled into a data matrix. Parsimony analysis was employed to generate hypotheses of phylogenetic relationships using the TNT 1.1. Proscyllium habereri was used to root the cladogram. The phylogenetic analysis, based on implied weighting (k = 3; 300 replications and 100 trees saved per replication), resulted in three equally most parsimonious cladograms with 233 steps, with a CI of 0.37 and an RI of 0.69. The monophyly of the subfamily Scyliorhininae is supported as well as of the genus Scyliorhinus, which is proposed to be the sister group of Cephaloscyllium. The phylogenetic relationships amongst Scyliorhinus species are presented for the first time.

Deep-neritic sediments of the Eferding Formation (Egerian, Upper Oligocene) of Upper Austria from the Kamig kaolinite quarry revealed minute teeth of the putatively planktivorous shark genus Nanocetorhinus. This is the oldest unambiguous record of this rarely documented genus, which was known so far only from Miocene deposits of Europe, North America and Japan. Based on previous studies, which showed a positive correlation between sediments of nutrient rich waters and plankton blooms with a majority of ichthyoliths of Keasius and Nanocetorhinus, we argue for a filter-feeding and migratory lifestyle of the latter. Thus, it is supposed that Nanocetorhinus migrated seasonally for foraging, in a similar way to the extant basking shark Cetorhinus maximus. This mode of life and the wide paleogeographic distribution of the open marine genus Nanocetorhinus requires a deep and fully marine connection between the Paratethys and the Proto-Mediterranean Sea during late Oligocene times, which might have been established via the Slovenian Corridor.

Chlamydoselachus anguineus, Garman 1884, commonly called the frilled shark, is a deep‐sea shark species occurring up to depths of 1300 m. It is assumed to represent an ancient morphotype of sharks (e.g., terminal mouth opening, more than five gill slits) and thus is often considered to represent plesiomorphic traits for sharks. Therefore, its early ontogenetic developmental traits are important for understanding the evolution of its particular phenotype. Here, we established six stages for prenatal embryos and used linear measurements and geometric morphometrics to analyse changes in shape and size as well as their timing during different embryonic stages. Our results show a change in head shape and a relocation of the mouth opening at a late stage of development. We also detected a negative allometric growth of the head and especially the eye compared to the rest of the body and a sexual dimorphism in total body length, which differs from the known data for adults. A multivariate analysis of covariance shows a significant interaction of shape related to the logarithm of centroid size and developmental stage. Geometric morphometrics results indicate that the head shape changes as a covariate of body size while not accounting for differences between sexes. The growth pattern of stages 32 and 33 indicates a shift in head shape, thus highlighting the moment in development when the jaws start to elongate anteriorly to finally achieve the adult condition of terminal mouth opening rather than retaining the early embryonic subterminal position as is typical for sharks. Thus, the antero‐terminal mouth opening of the frilled shark has to be considered a derived feature.

The Eastern Pacific Black Ghostshark Hydrolagus melanophasma (James et al. Zootaxa 2218:59–68, 2009) is a recently described deep water holocephalan found along the Eastern Pacific and so far known from a few records. Here we present new records for this species based on specimens collected as bycatch in the Chilean Seabass, Dissostichus eleginoides Smith, 1898 fishery at a depth of 1800 m off Taltal (25°S), northern Chile. This is the first record of Hydrolagus melanophasma in northern Chile, and its second occurrence in the southeastern Pacific, filling a gap in the distribution of the species and confirming its presence in the southeastern Pacific. We also report the first record of a Gyrocotyle species as parasite in this species.