Gulper Shark Research Articles

From rarity to reality: the hidden abundance of critically endangered deep-sea little gulper shark (Centrophorus uyato) in the southern Adriatic Sea

The little gulper shark, Centrophorus uyato (Rafinesque, 1810), is a critically endangered and poorly known deep-sea shark that is considered very rare in certain parts of the Mediterranean, particularly the Adriatic Sea. Between June and August 2023, a total of 47 individuals (25 females and 22 males) were documented 3 to 4.5 NM off Grama Bay in Vlorë, Albania, at depths ranging from 400 to 450 meters. All the recorded individuals were adults, measuring in average 90.53 cm total length and weighting 4.26 kg. Detailed examinations were performed on 10 individuals (5 males and 5 females), while the remaining specimens were retained by fishermen and subsequently sold for consumption. Local ecological knowledge revealed a consistent presence of the species in the longline catches in the studied area. The findings presented in the current manuscript indicate that the species may be more common in the southernmost Adriatic Sea than previously thought. Moreover, data herein support the postulation that the species prefer submarine canyons within the upper slopes.

Patterns of dermal denticle loss in sharks.

As they grow, sharks both replace lost denticles and proliferate the number of denticles by developing new (de novo) denticles without prior denticle shedding. The loss and replacement of denticles has potential impacts on the energetic cost of maintaining the skin surface, the biomechanical functions of shark skin, as well as our ability to predict shark abundance from fossil denticle occurrence in sediment cores. Here, we seek to better understand patterns of denticle loss and to show how denticles are being replaced in mature sharks. We illustrate shark skin surfaces with missing denticles and quantify both within-species and between-species patterns of missing denticles using images from across regions of the body for two species and images at similar body regions for 16 species of sharks. Generally, sharks are missing similar numbers of denticles (0%-6%) between species and regions. However, there are exceptions: in the smooth dogfish, the nose region is missing significantly more denticles than most posterior-body and fin regions, and the common thresher shark is missing significantly more denticles than the smooth dogfish, leopard shark, angel shark, bonnethead, and gulper shark. Denticle regrowth starts with crown development and mineralization beneath the epidermis, followed by eruption of the crown, and finally the mineralization of the root. The pulp cavity of replacement denticles is initially large and surrounded by a thin shell of enameloid upon eruption of the denticle. After eruption of the denticle, the deposition of dentine continues internally after the denticle reaches its final position. Replacement of missing denticles, representing less than 6% of the skin surface at any one time, may not compromise hydrodynamic function, but by constantly updating the skin surface throughout life, sharks may reduce surface fouling and maintain a functional complex skin surface by repairing local damage to individual denticles.

Ontogenetic Shifts in Body Morphology of Demersal Sharks' Species (Order: Squaliformes) Inhabiting the Western-Central Mediterranean Sea, with Implications for Their Bio-Ecological Role.

Several elasmobranch species undergo shifts in body proportions during their ontogenetic growth. Such morphological changes could reflect variation in diet, locomotion, or, more broadly, in the species' interactions with their environment. However, to date, only a few studies have been conducted on this topic, and most of them focused on particular body regions. In the present study, the ontogenetic growth of five different demersal shark species was investigated by using both traditional linear morphometry of the entire body and shape analysis of the caudal fin. A total of 449 sharks were analysed: 95 little gulper sharks, 80 longnose spurdogs, 103 kitefin sharks, 124 velvet belly lanternsharks, and 47 angular roughsharks. From each specimen, 36 linear morphometric measurements were taken. While a first canonical analysis of principal coordinates ruled out the possibility of different growth patterns between males and females, the same analysis statistically discriminated between small and large individuals in every species based on their morphology. A Similarity Percentage analysis revealed that the most important measurements in distinguishing these two groups were those related to body lengths, indicating that large individuals are more elongated than small individuals. The shape analysis of caudal fins revealed allometric growth during ontogenetic development, with adult individuals having a wider fin (discriminant analysis, p < 0.05). These findings could be related to changes in predatory skills, supporting the hypothesis of a shift in the ecological role that these sharks play in their environment, thus providing new essential information for their conservation.

First Record of the Little Gulper Shark, Centrophorus uyato (Rafinesque, 1810), in the Turkish Marine Waters of the North Aegean Sea

First Record of the Little Gulper Shark, Centrophorus uyato (Rafinesque, 1810), in the Turkish Marine Waters of the North Aegean Sea

Trophic Ecology of Deep-Sea Megafauna in the Ultra-Oligotrophic Southeastern Mediterranean Sea

The trophic ecology of fourteen species of demersal fishes and six species of demersal decapod crustaceans from the continental slope and rise of the Southeastern Mediterranean Sea (SEMS) was examined using stable isotope analysis. Mean δ13C values among fish species varied by ca. 4.0‰, from -20.85‰ (Macroramphosus scolopax) to -16.57‰ and -16.89‰ (Conger conger and Centrophorus granulosus), showing an enrichment in 13C as a function of depth (200 – 1400 m). Mean δ13C values of the crustaceans showed smaller variation, between -18.54‰ (Aristeus antennatus) and -16.38‰ (Polycheles typhlops). This suggests a shift from pelagic to regenerated benthic carbon sources with depth. Benthic carbon regeneration is further supported by the low benthic-pelagic POM-δ13C values, averaging -24.7 ± 1.2‰, and the mixing model results, presenting relatively low contribution of epipelagic POM to the deep-sea fauna. Mean δ15N values of fish and crustacean species ranged 7.91 ± 0.36‰ to 11.36 ± 0.39‰ and 5.96 ± 0.24‰ to 7.73 ± 0.46‰, respectively, resulting in trophic position estimates, occupying the third and the fourth trophic levels. Thus, despite the proximity to the more productive areas of the shelf, low number of trophic levels (TL~1.0) and narrow isotopic niche breadths (SEAC&amp;lt;1) were observed for demersal crustaceans (TL = 2.94 ± 0.18) and fishes (TL = 3.62 ± 0.31) in the study area – probably due to the ultra-oligotrophic state of the SEMS resulting in limited carbon sources. Our results, which provide the first trophic description of deep-sea megafauna in the SEMS, offer insight into the carbon sources and food web structure of deep-sea ecosystems in oligotrophic marginal seas, and can be further used in ecological modeling and support the sustainable management of marine resources in the deep Levantine Sea.

Revision of the genus Centrophorus (Squaliformes: Centrophoridae): Part 3—Redescription 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). The first paper in this revision series clarified that C. granulosus refers to a much larger species of gulper shark which attains at least 1.7 m length and is absent from the Mediterranean Sea. Further complicating the nomenclature of this species is the fact that the original description clearly refers to a Squalus species, and not a Centrophorus species. In this third part of the revision of the genus Centrophorus, this problematic species is redescribed. A detailed synonymy is provided and it is confirmed that C. machiquensis, C. bragancae and C. zeehaani are junior synonyms of this species. To preserve nomenclatural stability within the genus, the name Centrophorus uyato is retained for this species with a neotype from close to the original type locality off Italy being designated. Intraspecific variation within Centrophorus uyato is also discussed, particularly relating to denticle morphology and body morphology.

Call me by my name: unravelling the taxonomy of the gulper shark genus Centrophorus in the Mediterranean Sea through an integrated taxonomic approach

Abstract The current shift of fishery efforts towards the deep sea is raising concern about the vulnerability of deep-water sharks, which are often poorly studied and characterized by problematic taxonomy. For instance, in the Mediterranean Sea the taxonomy of genus Centrophorus has not been clearly unravelled yet. Since proper identification of the species is fundamental for their correct assessment and management, this study aims at clarifying the taxonomy of this genus in the Mediterranean Basin through an integrated taxonomic approach. We analysed a total of 281 gulper sharks (Centrophorus spp.) collected from various Mediterranean, Atlantic and Indian Ocean waters. Molecular data obtained from cytochrome c oxidase subunit I (COI), 16S ribosomal RNA (16S), NADH dehydrogenase subunit 2 (ND2) and a portion of a nuclear 28S ribosomal DNA gene region (28S) have highlighted the presence of a unique mitochondrial clade in the Mediterranean Sea. The morphometric results confirmed these findings, supporting the presence of a unique and distinct morphological group comprising all Mediterranean individuals. The data strongly indicate the occurrence of a single Centrophorus species in the Mediterranean, ascribable to C. cf. uyato, and suggest the need for a revision of the systematics of the genus in the area.

Sharks, rays and chimaeras of the Seine and Unicorn seamounts (NE Atlantic Ocean)

BackgroundSeamounts are underwater mountains which typically rise rather steeply at least several hundred meters above the deep-sea floor. These geological features interrupt water flow and hence may induce changes in the circulation of different water masses, in turn causing different physical and biological effects. For this reason, seamounts are biodiversity hotspots, housing a wide number of species, as is with the case of the Seine and Unicorn seamounts, which are a part of the Madeira-Tore seamount chain located between Portugal mainland, southwestern Europe and Madeira archipelago (NE Atlantic).MethodsFisheries independent surveys allowed the collection of Chondrichthyes specimens from the Seine and Unicorn seamounts. Individuals were caught over the course of two research cruises, first in 2004 and later in 2017, with species distribution ranging from the summit down to 2500 m of depth.ResultsFifteen species belonging to 7 different taxonomical families were collected in the two surveyed areas. Two species were recorded for the first time and added to the checklist of the Seine seamount (Centrophorus granulosus and Somniosus rostratus), and three species for the Unicorn seamount (C. granulosus, Centroscymnus coelolepis and Centroselachus crepidater). Distribution and frequency of occurrence for the collected species were evaluated in relation to depth.ConclusionsThis work is a valuable contribution to the knowledge of seamount-associated fish fauna. Moreover, the checklist of sharks, rays and chimaeras was updated for the Seine and Unicorn seamounts, summing up 20 species.

First genetically confirmed records of the little gulper shark Centrophorusuyato (Squaliformes: Centrophoridae) from Cypriot waters.

The taxonomy within the genus Centrophorus has been controversial almost since its origin, raising uncertainties about the identification, the phylogenetic placement and the geographical distribution of several species. The partial nucleotide sequences of two mitochondrial DNA gene regions, the cytochrome c oxidase subunit I and the 16S ribosomal RNA, genetically confirmed the presence of the little gulper shark in Cypriot waters. The species presence in the Mediterranean Sea is revised and discussed.

Shark fossil diversity (Squalomorphii, Squatinomorphii, and Galeomorphii) from the Langhian of Brielas (Lower Tagus Basin, Portugal)

The fossiliferous marine Miocene sediments of the Lower Tagus Basin (Portugal) present a great diversity of Chondrichthyes forms. The current study focuses on the fossil sharks from the Langhian Vc unit of the Brielas section, located in the Setúbal Peninsula. A total of 384 isolated fossil teeth were analysed and ascribed to 17 species from the Orders Hexanchiformes, Squaliformes, Squatiniformes, Lamniformes, and Carcharhiniformes.Centrophorus granulosusandIago angustidensare described for the first time in Portuguese sediments, whereasPachyscyllium dachiardiiandRhizoprionodon ficheurirepresent only their second reported occurrence.Galeorhinus goncalvesiwas already known from the Portuguese uppermost Miocene (Alvalade Basin), but it is now recognized in older sediments. Furthermore, the new material seems to include the first reported occurrence ofHexanchuscf.agassiziin Miocene sediments. As a whole, these new findings support the previous palaeoenvironment characterization of a warm infralittoral setting gradually deepening to a circalittoral one, where seasonal upwelling phenomena could have occurred.

Assessment of trends in the Portuguese elasmobranch commercial landings over three decades (1986–2017)

Portugal plays a major role in shark, skate and ray fisheries in the European Union. With the decline of these animals raising concerns amongst scientists all over the world, we set out to provide an updated assessment on elasmobranch landings in Portugal between 1986 and 2017. The dataset analysed in this study consisted of 15,521 records, each with information concerning the species (or higher taxonomic level), port, month, year, and weight of fish landed. A non-parametric change points assessment statistical technique was used to evaluate important changes in landings throughout the time series. Principal components analysis was also performed to mean values of landings per year for the most captured species, and similar analysis was conducted using fishing ports instead of year, for the same sub-set of species / taxa. According to the data, more than 143 thousand metric tons of elasmobranchs were landed in Portuguese ports between 1986 and 2017, divided by 58 taxa of sharks, skates and rays. The most landed taxa were demersal rays and skates (Raja spp.), followed by spotted dogfishes (Scyliorhinus spp.), blue shark (Prionace glauca), Portuguese dogfish (Centroscymnus coelolepis), leafscale gulper shark (Centrophorus squamosus), gulper shark (Centrophorus granulosus) and shortfin mako (Isurus oxyrinchus). Together, these seven taxa accounted for more than 75% of all landings. Several cases of misreporting were identified and discussed. Overall, landings of elasmobranchs in Portugal show marked decreases and changes in composition, with deep-sea sharks being the most influential group during the studied period.

Characteristics Squalene of Smallfin Gulper Shark (Centrophorus moluccensis) Livers From Aru Islands, Mollucas, Indonesia

Smallfin gulper sharks (Centrophorus moluccensis) commercially exploited as food ingredient and contain high squalene in their livers. The purpose of this study was to determine the quality and composition of smallfin gulper shark liver oil compounds from the Aru Island waters, Mollucas, Indonesia. Smallfin gulper shark liver oil extraction uses a dry rendering method. The quality was analyzed based on the analysis procedure in SNI 01-2730-1992 regarding the quality standards of fish oil. Meanwhile, to find out the fatty acid content, an analysis was performed using GC-MS. The results showed that the quality of smallfin gulper shark liver oil generally met the quality standard with a yield of 83%, while the compounds composition was dominated by squalene compound of the remaining 95.10% in the form of palmitic acid, α-linolenic acid, EPA and DHA.

ANALYSIS OF SUPERIOR COMMODITIES OF MARINE CAPTURE FISHERIES IN CENTRAL BANGKA REGENCY, INDONESIA

This research aims to analyze the superior commodities of catch fisheries subsector in Central Bangka Regency. The method that was used in this research is descriptive method. The analysis approach which were used are Location Quotient (LQ), Shift Share analysis (SSA), and Typology Klassen (TK). Based on the results of the research, the catch fisheries subsector in Central Bangka Regency is a potential and non base subsector, but growing faster in The Province of Bangka Belitung Islands. Based on the results of the analysis of LQ, SSA and TK acquired the superior commodities of catch fisheries in Central Bangka Regency consists of 11 commodities seen from production (tonnes) and value of the production (Rp). These types of fish are mullet, black-barred halfbeak, indian mackerel, scad fish, smallfin gulper shark, smalltooth sand tiger, dorab wolf-herring, tonguesole fish, sharpnose hammer croaker, crabs, and swimming crabs. Based on the results of this research recommended to continue to maintain the conditions of the fishing ground for the 9 types of fish caught, keep the fishing trip so that production is maintained for regional income and increasing the welfare of fishermen in Central Bangka Regency.

Bottom trawling activity, main fishery resources and associated benthic and demersal fauna in a mud volcano field of the Gulf of Cádiz (southwestern Iberian Peninsula)

Bottom trawling activity, commercial species and benthic and demersal assemblages were studied integrating Vessel Monitoring System data (VMS), fishing logbook data and otter trawl samples in a mud volcano (MV) field of the Spanish margin of the Gulf of Cádiz (GoC) in 2011. High trawling activity was detected around Anastasya MV and between the Cádiz and Guadalquivir diapiric ridges, and low trawling activity around Gazul MV and in the deepest areas (Huelva Channel and southwards). A total of 11938 individuals from 126 benthic and demersal species were collected in the samples. Multivariate analyses mainly grouped samples according to depth and sediment type and 3 different assemblages were detected. The Stratum 1 assemblage (Gazul MV, 441–470 m depth, muddy sand, low trawling activity and high near-bottom current speed) was dominated by Parapenaeus longirostris, Leptometra phalangium and Plesionika antigai, among others, and displayed high species richness and abundance. The Stratum 2 assemblage (Anastasya and Tarsis MVs, Triangle, and the External zone, 528–622 m, mud/sandy mud, medium to high trawling activity and low near-bottom current speed) was dominated by P. longirostris, Plesionika martia, Nezumia aequalis and small chondrichthyans (mainly sharks), among others, and displayed low species richness, abundance and biomass. The Stratum 3 assemblage (Huelva Channel > 700 m, sand, low trawling activity and high near-bottom current speed) was dominated by similar species to Stratum 2, but also included large demersal sharks (Centrophorus granulosus, Galeorhinus galeus, Dalatias licha) that resulted in a high biomass. Depth and near-bottom current speed showed strong relationships with the benthic and demersal assemblages in Principal Component Analyses. The occurrence of medium to intense trawling activity in and around some MVs (Habitat 1180, Council Directive 92/43/ECC-Habitats Directive) should imply an effective regulation that allows a balance between sustainable fisheries and habitat conservation.

A community assessment of the demersal fish and benthic invertebrates of the Rosemary Bank Seamount marine protected area (NE Atlantic)

The Rosemary Bank Seamount in the NE Atlantic was designated a Marine Protected Area in 2014 by the Scottish Government. Visual and trawl surveys of the seamount have been undertaken since 2007. Here these data are compiled and analysed to provide an assessment of the communities of demersal fish and benthic invertebrates found there. The fish and benthic invertebrate communities changed markedly with depth. Cluster analysis revealed at least four distinct communities of fish: those on the summit, the mid slope, the lower slope and the deep moat at the base of the seamount. The invertebrate community changed at a depth of 1100 m, where mixed-species sponge aggregations dominated to depths of 1500 m. The seamount is an important site for vulnerable marine ecosystems, most notably the extensive and unusually diverse deep-sea sponge grounds on the lower slope. Other prioritised conservation species and habitats recorded included cold water corals, orange roughy, blue ling, leafscale gulper shark and the Portuguese dogfish. Due to sampling constraints some areas of the seamount still remain unknown. A precautionary approach to protecting the entire seamount would achieve multiple conservation objectives. The data presented here serve as a base-line to assess the impact of management intervention in the future.

A new species of parasitic copepod (Siphonostomatoida: Lernaeopodidae: Neoalbionella Özdikmen, 2008) infecting the skin of a gulper shark, Centrophorus sp. (Squaliformes: Centrophoridae), in the Gulf of Mexico, with a key to species of Neoalbionella

AbstractWe describe male and female specimens of a species of NeoalbionellaÖzdikmen, 2008 (Siphonostomatoida, Lernaeopodidae), Neoalbionella dannytangisp. nov., infecting the skin of a gulper shark Centrophorus sp. (Centrophoridae) in the northern Gulf of Mexico. Females of the new species most closely resemble those of Neoalbionella globosa (Leigh-Sharpe, 1918) but are unique among congeners by having the combination of 1) terminal endopodal segment of antenna with a reduced distal tubercle having a minute protuberance, 2) maxillule with a spinulose lateral palp and praecoxal endite, 3) maxilla with a swollen tip nearly parallel with the distal surface of the bulla, and 4) maxilliped with a sub-circular spinulose pad along the proximal myxal margin of the corpus maxillipedis. The male copepod was attached to the tip of a female’s posterior process and was assigned to Neoalbionella by having a cephalosome nearly equal in length to the trunk and tapered caudal rami directed posteroventrally (swollen and directed anterodorsally in males of Lernaeopoda von Nordmann, 1832). It was distinct from those of all other congeners by having 1) an antenna terminal endopodal segment and maxillule similar to that of the female, 2) a maxilla syncoxa with an anteromedial process having seven large, conical denticles, 4) a bifid mediative process approximately as wide as the length of the shortest lobe, and 5) a caudal ramus with a unique configuration and number of setae. This is the second report of a species of Neoalbionella from the Gulf of Mexico and the third nominal species of Neoalbionella reported from gulper sharks (Centrophorus spp.). We also provide keys to females and males of Neoalbionella.

Simulation-based evaluation of reserve network performance for Centrophorus zeehaani (Centrophoridae): a protected deep-sea gulper shark

Abstract Resource use and conservation objectives can conflict where protected species and commercially fished species occur together. We tested the potential for a previously overfished deep-sea shark (Centrophorus zeehaani) with very low biological productivity to recover in a network of three reserves. An individual-based simulation model was developed and applied using reproduction and movement data. Without any reserves or reductions in fishing mortality the population will never recover and will fail in 27.9 ± 6.1 years. With three reserves, recovery from 8% of initial numbers to a target of 20% would take 63.1 ± 3.1 years with the network in place. Length of the female cycle, natural mortality, and density dependent female dispersal are uncertain, but could delay recovery time by an additional 16.5, 98.3, or 61.9 years, respectively. Effectiveness of the reserve network was particularly sensitive to location and patchiness of the population. Doubling the size of a reserve where C. zeehaani are abundant would reduce recovery time by 12.5 years; halving it would increase recovery time by 12.0 years. Future re-opening of orange roughy fishing in waters deeper than 750 m would delay recovery of C. zeehaani by 45.9 years. The methods developed here can be used to explore co-management options for target species and protected species in fisheries.

A New Species of Neoalbionella (Copepoda: Siphonostomatoida: Lernaeopodidae) from Skin of the Gulper Shark, Centrophorus Granulosus (Squaliformes: Centrophoridae) in the Northern Gulf of Mexico

Using light and scanning electron microscopy of male and female copepods, we herein describe a new species of Neoalbionella Özdikmen, 2008 (Copepoda: Lernaeopodidae), Neoalbionella benzipirata n. sp., infecting the skin of the gulper shark, Centrophorus granulosus (Bloch and Schneider, 1801), in the northern Gulf of Mexico. Females of the new species were assigned to Neoalbionella by having 3 setae on the maxillule lateral palp (vs. 2 setae in Lernaeopoda Nordmann, 1832) and a single accessory denticle on the maxilliped subchela claw (vs. ≥2 denticles in Lernaeopoda). Females of the new species resemble those of Neoalbionella longicaudata ( Hansen, 1923 ) Özdikmen, 2008 but can be differentiated from them and those of all congeners by having a unique configuration of 16 dorsocephalic sensilla; an antennule terminal segment having 6 apical setae comprising tubercles 1 and 3, digitiform seta 4, 2 subequal setae of complex 5, and flagelliform seta 6; an antenna exopod with a thickened dorsal ridge, smooth (convex) outer surface with 2 short papillae, and rugose (concave) inner surface plus a terminal endopodal segment having a large dorsal hook, medial spine, bifid distal tubercle, and spinulose ventral process; a mandible having the formula P1, S1, P1, S1, P1, S1, B5; and a single pair of anterolateral spines on the mouth cone labium. Males attached to the posteroventral surface of the females' genital trunk were assigned to Neoalbionella by having tapered (not inflated) caudal rami directed posteroventrally. They were differentiated from previously reported congeneric males by having an antennule with the same number and configuration of apical setae as the female; an antenna with a spatulate exopod having minute spinules along its apex plus a terminal endopodal segment with components the same as the female; a mandible with formula P2, S1, P1, S1, B5; a labium with 1 pair of anterolateral spines like the female; and a conspicuous mediative process with bifid tip. Detail of the dorsocephalic shield (in females) and mouth cone labium (in both sexes) previously had not been used to diagnose Neoalbionella spp. We also dissected voucher specimens of " Neoalbionella longicaudata" (collected from gulper sharks in the western Pacific Ocean off Japan by Shiino in 1956), which we morphologically diagnosed as an innominate species, Neoalbionella sp. This is the first report of a species of Neoalbionella from the Gulf of Mexico and the second species of Neoalbionella reported from C. granulosus, a deepwater shark seldom encountered and surveyed for parasitology.

New records of sharks (Elasmobranchii) from the Andaman and Nicobar Archipelago in India with notes on current checklists.

The diversity of sharks occurring off the Andaman and Nicobar Archipelago in India has received increased attention in recent years. Yet, available checklists are out of date, often with inaccurate information and a number of commercially important species have not been documented through research and fish landing surveys. Here we report on shark species examined during fish landing surveys conducted from January 2017 to April 2018. Records of twelve previously unreported species from the archipelago are presented and include the bignose shark (Carcharhinus altimus), pigeye shark (Carcharhinus amboinensis), bull shark (Carcharhinus leucas), snaggletooth shark (Hemipristis elongata), slender weasel shark (Paragaleus randalli), Arabian smoothhound shark (Mustelus mosis), Indonesian houndshark (Hemitriakis indroyonoi), sand tiger shark (Carcharias taurus), Indonesian bambooshark (Chiloscyllium hasseltii), tawny nurse shark (Nebrius ferrugineus), dwarf gulper shark (Centrophorus atromarginatus), and the Indonesian shortsnout spurdog (Squalus hemipinnis). These records increase the reported shark species for the archipelago from 47 to 59 and for India from 114 to 116. Additionally, a size extension in the total length of C. hasseltii by 27 cm and of P. randalli by 8 cm is reported. Owing to the bio-geographical location of these islands, species diversity around the archipelago is unique and appears to overlap with that of southeast Asia. With increasing reports of over-exploitation and the operation of a targeted shark fishery by distant water fleets in these waters, the limited information on shark diversity from this region is of concern. Systematic and long-term monitoring of catches, combined with accurate species identification, is crucial to provide information on management measures.

Planonasus indicus sp. n., a new species of pygmy false catshark (Chondrichthyes: Carcharhiniformes: Pseudotriakidae), with a revised diagnosis of the genus and key to the family

A new species of the genus Planonasus is described from off southwestern India and Sri Lanka in the northern Indian Ocean. The new species occurs along the upper continental slope from 200 to 1000 m deep and was landed in fisheries for gulper sharks (Centrophorus spp.). Planonasus indicus sp. n. externally closely resembles P. parini (Carcharhiniformes: Pseudotriakidae), the only other member of the genus. It can be distinguished from P. parini by a combination of morphological characters including absence of oral papillae, lack of a distinct white mark on the free rear tip of the first dorsal fin, sides and underside of head, as well as fin edges that are similar in color as body (vs. dusky), more tooth rows in the lower jaw, shorter labial furrows, longer and less high spiracles, proportionally higher, more angular dorsal fins, especially the second dorsal fin, proportionally longer pectoral fins, a proportionally larger anal fin, longer distances from the snout tip to the origins of the caudal fin, both dorsal fins and the pelvic fins, as well as to the vent, and shorter distances for preorbital snout, prepectoral length, pelvic midpoint to second dorsal fin origin, and pelvic-anal space. A revised diagnosis of the genus and key to the family is also provided.