Overfishing and climate change elevate extinction risk of endemic sharks and rays in the southwest Indian Ocean hotspot.

Here, we summarise the extinction risk of the sharks and rays endemic to coastal, shelf, and slope waters of the southwest Indian Ocean and adjacent waters (SWIO+, Namibia to Kenya, including SWIO islands). This region is a hotspot of endemic and evolutionarily distinct sharks and rays. Nearly one-fifth (n = 13 of 70, 18.

Fishing for oil and meat drives irreversible defaunation of deepwater sharks and rays.

The deep ocean is the last natural biodiversity refuge from the reach of human activities. Deepwater sharks and rays are among the most sensitive marine vertebrates to overexploitation. One-third of threatened deepwater sharks are targeted, and half the species targeted for the international liver-oil trade are threatened with extinction.

First records of the Pacific sleeper shark Somniosus cf. pacificus in the western tropical Pacific.

Technological advances have enabled the expansion of ocean exploration to include the deep ocean, providing new species observations. Here, the authors present two new observations, captured by deep-sea cameras, of the sleeper shark Somniosus cf. pacificus from the Solomon Islands and Palau.

Comparative analyses of the complete mitochondrial genomes of two southern African endemic guitarfish, Acroteriobatus annulatus and A. blochii.

Shark-like rays (order Rhinopristiformes) are among the most threatened cartilaginous fish globally. Despite this, unresolved taxonomic issues still exist within the group. To date, no studies have used complete mitochondrial genomes to assess the phylogenetic placement of Acroteriobatus within the non-monophyletic family Rhinobatidae.

A taxonomic revision of Northeast Pacific softnose skates (Rajiformes: Arhynchobatidae: Bathyraja Ishiyama).

Softnose skates (Rajiformes: Arhynchobatidae: Bathyraja Ishiyama) are the most diverse skate genus, with 54 species, and are readily distinguishable from other genera in the family by their poorly calcified, flexible rostral cartilages. Six Bathyraja species are considered valid in the eastern North Pacific, including: B. abyssicola, B.

Revision of the genus Centrophorus (Squaliformes: Centrophoridae): Part 3Redescription of Centrophorus uyato (Rafinesque) with a discussion of its complicated nomenclatural history.

Centrophorus uyato (Rafinesque, 1810) has a complicated nomenclatural history which has led to multiple scientific names being ascribed to this species. In the Mediterranean Sea, and elsewhere in its range, this species was previously referred to as C. granulosus (Bloch Schneider, 1801).

Overfishing drives over one-third of all sharks and rays toward a global extinction crisis.

The scale and drivers of marine biodiversity loss are being revealed by the International Union for Conservation of Nature (IUCN) Red List assessment process. We present the first global reassessment of 1,199 species in Class Chondrichthyes-sharks, rays, and chimeras. The first global assessment (in 2014) concluded that one-quarter (24%) of species were threatened.

An annotated checklist of the chondrichthyans of South Africa.

An annotated checklist of chondrichthyan fishes (sharks, batoids, and chimaeras) occurring in South African waters is presented. The checklist is the result of decades of research and on-going systematic revisions of the regional fauna. The chondrichthyan fauna of South Africa is one of the richest in the world with 191 species, comprising 50 families and 103 genera.

Leucoraja elaineae sp. nov., a new rough skate (Rajiformes: Rajidae) from the Western Indian Ocean.

A new species of the genus Leucoraja is described from off Kenya in the Western Indian Ocean (WIO). The new species was collected during a survey of the R/V Fridtiof Nansen. Leucoraja elaineae sp.

New insights into the identities of the elasmobranch fauna of Sri Lanka.

Identities of elasmobranchs from Sri Lanka encountered during collections conducted in an intensive nine-day survey of fish markets and landing sites at 11 localities in the North Western, Northern, and Eastern Provinces in March of 2018 were assessed. In total, 111 specimens representing 34 elasmobranch species were examined. Sequence data for the NADH2 gene were generated for all specimens.

Redescription and taxonomic status of Dipturus chilensis (Guichenot, 1848), and description of Dipturus lamillai sp. nov. (Rajiformes: Rajidae), a new species of long-snout skate from the Falkland Islands.

Recent molecular evidence has called into question the identity of skates collected in the waters off the Falkland Islands previously identified as Zearaja chilensis. NADH2 sequence data indicate that these specimens are not conspecific with those currently referred to as Z. chilensis from Chile and, in fact, represent a novel cryptic species.

Etmopterus marshae sp. nov, a new lanternshark (Squaliformes: Etmopteridae) from the Philippine Islands, with a revised key to the Etmopterus lucifer clade.

A new species of lanternshark, Etmopterus marshae (Squaliformes: Etmopteridae), is described from the Philippine Islands, western North Pacific Ocean. The new species occurs along insular slopes at a depth range of 322-337 m. The new species resembles other members of the "Etmopterus lucifer" clade in having linear rows of dermal denticles, and most closely          resembles E.

Parmaturus nigripalatum n. sp., a new species of deep-sea catshark (Chondrichthyes: Carcharhiniformes: Scyliorhinidae) from Indonesia.

Parmaturus nigripalatum, a new species of catshark of the genus Parmaturus is described from a single specimen collected from a deep-water shark longliner operating in south Sumbawa waters, Indonesia. This new species is distinguished from its closest geographic congener P. lanatus by having prominent enlarged caudal crests, well-developed labial furrows with the uppers and lowers of equal lengths, mouth roof blackish with dark pores, first dorsal fin origin more posteriorly positioned on body trunk, and much lower tooth counts than all other known Parmaturus species.

Revision of the genus (Squaliformes: Centrophoridae): Part 2-Description of two new species of and clarification of the status of Barbosa du Bocage & de Brito Capello, 1864.

Centrophorus specimens with a distinctive long-based first dorsal fin (long-finned species) have previously been considered to be Centrophorus lusitanicus first described from Portugal. Critical examination of the original description and illustration reveal that C. lusitanicus should be considered a junior synonym of C.

Biodiversity, Life History, and Conservation of Northeastern Pacific Chondrichthyans.

The sharks, batoids, and chimaeras, collectively the class Chondrichthyes, are one of the most successful groups of fishes, with over 1250 species globally. Recent taxonomic revisions have increased their diversity by about 20% over the past 17 years (2000-2016). The Northeast Pacific Ocean is one of the top 20 most diverse regions/countries on the globe with 77 chondrichthyan species, a number less than a quarter that of the most species-rich area (Australia) but that has increased by 10% since 2000 to include three new species (two skates and a chimaera).

Age and Growth of Elasmobranchs and Applications to Fisheries Management and Conservation in the Northeast Pacific Ocean.

In addition to being an academic endeavour, the practical purpose of conducting age and growth studies on fishes is to provide biological data to stock assessment scientists and fisheries managers so they may better understand population demographics and manage exploitation rates. Age and size data are used to build growth models, which are a critical component of stock assessments. Though age determination of elasmobranchs in the northeast Pacific Ocean (NEP) began in the 1930s, the field has evolved substantially in recent years, allowing scientists to incorporate age data into assessments for more species than ever before.

n. sp., a new species of guitarfish (Rhinopristiformes: Rhinobatidae) from the Southwestern Indian Ocean.

Rhinobatos austini sp. n. is described from the southwestern Indian Ocean based on four specimens collected from the KwaZulu-Natal Province, South Africa and from Mozambique.

n. sp., a new lanternshark (Squaliformes: Etmopteridae) from Papua New Guinea.

A new species of lanternshark, Etmopterus samadiae (Squaliformes: Etmopteridae), is described from off northern Papua New Guinea, in the western Central Pacific Ocean. The new species resembles other members of the "Etmopterus lucifer" clade in having linear rows of dermal denticles and most closely resembles E. brachyurus from the western North Pacific.

sp. nov., a new lanternshark (Squaliformes: Etmopteridae) from the Northwestern Hawaiian Islands.

A new species of lanternshark, Etmopterus lailae (Squaliformes: Etmopteridae), is described from the Northwestern Hawaiian Islands, in the central North Pacific Ocean. The new species resembles other members of the "Etmopterus lucifer" clade in having linear rows of dermal denticles, and most closely resembles E. lucifer from Japan.

An evaluation of mercury offloading in two Central California elasmobranchs.

Elasmobranchs occupy high trophic levels, accumulate high concentrations of mercury in their tissues, and have high energetic levels of maternal investment to offspring, which may cause embryos to be exposed in utero to harmful concentrations of mercury. We investigated the maternal transfer of mercury in two common coastal elasmobranch species, Triakis semifasciata and Platyrhinoidis triseriata, to determine which reproductive parameters may influence mercury offloading, and whether embryos are at risk to mercury toxicity. Mercury concentration was measured in female muscle, female liver, and embryonic tissues.

sp. nov. (Chimaeriformes: Chimaeridae), a new species of chimaerid from the southeastern Atlantic and southwestern Indian oceans.

A new species of chimaerid, Hydrolagus erithacus sp. nov., is described from nine specimens collected from the southeast Atlantic and southwest Indian oceans from depths of 470-1,000 meters.

n. sp., a new deep-water catshark (Carcharhiniformes, Scyliorhinidae) from the southwestern Indian Ocean, with a review of species and a key to their identification.

A new deep-water catshark, Bythaelurus bachi, is described based on 44 specimens caught on the southern Madagascar Ridge in the southwestern Indian Ocean. The new species is the only stout-bodied Bythaelurus with oral papillae in the region and is distinguished from all congeners by the plain beige to light gray-brown coloration, high diversity in dermal denticle morphology, and presence of composite oral papillae. Despite resemblance in body shape, Bythaelurus bachi n.

Notoraja martinezi sp. nov., a new species of deepwater skate and the first record of the genus Notoraja Ishiyama, 1958 (Rajiformes: Arhynchobatidae) from the eastern Pacific Ocean.

A new arhynchobatid skate, Notoraja martinezi, sp. nov., is described from four specimens collected from the eastern Central Pacific from Costa Rica to Ecuador and between depths of 1256-1472 m.