The genus Grimpoteuthis (Octopoda: Grimpoteuthidae) in the north-east Atlantic, with descriptions of three new species

The systematics and distribution of the cirrate octopod genus Grimpoteuthis in the north-east Atlantic are reviewed. Three new species are described and Grimpoteuthis wuelkeri (Grimpe, 1920) is redescribed. A new generic diagnosis is proposed. Five species of Grimpoteuthis are recognized in the north-east Atlantic. The type species, G. umbellata (Fisher, 1883) is known only from the type specimen, which is in such poor condition that comparison with recently captured material was not possible. G. wuelkeri is a large, slope species, caught between 1600 m and 2200 m in the north-east and north-west Atlantic. Of the three new species, both G. boylei and G. challengeri are large abyssal species. G. boylei is found in the north-east Atlantic at the Porcupine Abyssal Plain (PAP) and the Madeira Abyssal Plain and may be found at abyssal depths throughout the north-east Atlantic. G. challengeri is known from the PAP, with a single specimen from the north-west Atlantic. G. discoveryi is a small, lower slope and abyssal species found in the north-east Atlantic. The Grimpoteuthis species can be separated based on shell form, presence of a radula and posterior salivary glands, arrangement of suckers and cirri and gill morphology. Two species, G. megaptera Verrill and G. plena Verrill, have been described from the north-west Atlantic, but the types are either lost ( G. megaptera ) or in poor condition ( G. plena ), hindering comparisons. Material examined from the north-west Atlantic included G. wuelkeri , G. challengeri and at least two other species.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society , 2003, 139 , 93−127.     

Occurrence of pelagic stingray Pteroplatytrygon violacea (Bonaparte, 1832) in the North Sea

A mature male pelagic stingray Pteroplatytrygon violacea (99 cm total length, 33·5 cm disc length and 42 cm disc width; 2·5 kg) was caught by commercial Nephrops trawl in the North Sea (at c . 54º49' N; 0º57' W) on 14 November 2005. Records of P. violacea in the north-east Atlantic are reviewed, with only two vagrant specimens known from the North Sea, representing the most northerly records of this species in the Atlantic Ocean.     

Upside-down swimming: in situ observations of inverted orientation in Gigantactis,with a new depth record for the Ceratioidei

This note reports on eight observations of inverted swimming behavior by species of ceratioid whipnose anglerfishes in the genus Gigantactis, from the Caribbean, tropical east Atlantic, tropical western Indian Ocean, the north-east and north-west Pacific and south-west Pacific. It covers four putative species and strongly suggests that this is the normal behavior for the genus. A possible reason is briefly discussed. In addition, a new depth record of 5866 m for the ceratioid anglerfish is recorded.     

On a new Dictyna species (Araneae, Dictynidae) from the northern Palaearctic confused with the East Siberian D. schmidti Kulczyński, 1926

A new species, Dictyna palmgrenisp. n., is described from Finland and Russia on the basis of both sexes. Most of the earlier records of Dictyna schmidti Kulczyński, 1926 from the northern Palaearctic refer to this new species. Dictyna shilenkovi Danilov, 2000, syn. n. from Cisbaikalia is synonymised with Dictyna schmidti. The general appearances and copulatory organs of Dictyna palmgrenisp. n., Dictyna schmidti and Dictyna major Menge, 1869 are illustrated. The distribution of Dictyna palmgrenisp. n. andDictyna schmidti is clarified. An unknown sac-like structure of the spermathecae of Dictyninae is briefly discussed.     

Genetic diversity and population structure of the blue jack mackerel Trachurus picturatus across its western distribution

Blue jack mackerel Trachurus picturatus collected at six sampling locations of the north-east Atlantic Ocean (Azores, Madeira, Canaries, and Matosinhos, Peniche and Portimão, mainland Portugal) and one location in the Mediterranean (Sicily), were used to examine the genetic structure of this species. Three mitochondrial gene regions (cytochrome c oxidase subunit I, cytochrome b and control region) were used to study the genetic structure of the species in Macaronesia, as well as to compare the genetic diversity of this region with published results from its eastern distribution. All markers indicated the absence of genetic structure among populations, with high indices of genetic diversity. These results suggest that the species went through a bottleneck event, followed by a recent population expansion. Moreover, the comparison with previously published results from the T. picturatus Mediterranean distribution suggests the existence of a single panmictic population throughout the species' full range. This was, however, an unexpected result since other methodologies have shown the presence of, at least, three different population-units in the NE Atlantic Ocean.     

Deep-sea asellote isopods of the north-east Atlantic: the family Dendrotionidae and some new ectoparasitic copepods

A new species of Dendromunna and two new species of Dendrotion are described from abundant material collected in the Rockall Trough region of the north-east Atlantic. The taxonomy of the little known benthic deep-sea asellote isopod family Dendrotionidae is reviewed and keys provided for genera and species. Also diagnosed and described are two new species belonging to a new genus of siphonostomatoid copepod found as ectoparasites on the walking legs of the new Dendromunna. The new parasites belong in the Rhizorhina group of genera within the family Nicothoidae.     

Description of a New Species of Pelagic Eelpout Melanostigma thalassium sp. nova (Zoarcidae) from Walvis Ridge (Southeastern Atlantic) and Identification Key for Species of the Genus from the Atlantic Ocean

Journal of Ichthyology - A new species Melanostigma thalassium sp. n. is described from the underwater Walvis Ridge (Southeast Atlantic Ocean). This species differs from the other species of the...     

Evolutionary diversification of banded tube-dwelling anemones (Cnidaria; Ceriantharia; Isarachnanthus) in the Atlantic Ocean

The use of molecular data for species delimitation in Anthozoa is still a very delicate issue. This is probably due to the low genetic variation found among the molecular markers (primarily mitochondrial) commonly used for Anthozoa. Ceriantharia is an anthozoan group that has not been tested for genetic divergence at the species level. Recently, all three Atlantic species described for the genus Isarachnanthus of Atlantic Ocean, were deemed synonyms based on morphological simmilarities of only one species: Isarachnanthus maderensis. Here, we aimed to verify whether genetic relationships (using COI, 16S, ITS1 and ITS2 molecular markers) confirmed morphological affinities among members of Isarachnanthus from different regions across the Atlantic Ocean. Results from four DNA markers were completely congruent and revealed that two different species exist in the Atlantic Ocean. The low identification success and substantial overlap between intra and interspecific COI distances render the Anthozoa unsuitable for DNA barcoding, which is not true for Ceriantharia. In addition, genetic divergence within and between Ceriantharia species is more similar to that found in Medusozoa (Hydrozoa and Scyphozoa) than Anthozoa and Porifera that have divergence rates similar to typical metazoans. The two genetic species could also be separated based on micromorphological characteristics of their cnidomes. Using a specimen of Isarachnanthus bandanensis from Pacific Ocean as an outgroup, it was possible to estimate the minimum date of divergence between the clades. The cladogenesis event that formed the species of the Atlantic Ocean is estimated to have occured around 8.5 million years ago (Miocene) and several possible speciation scenarios are discussed.     

Melanostigma meteori sp. n. (Zoarcidae): A New Pelagic Eelpout Species from the Meteor Bank (Southeastern Atlantic), with Remarks on the Polymerization of the Lateral Line in the Family

Journal of Ichthyology - A new species, Melanostigma meteori sp. n., is described from the Meteor Bank (southeastern Atlantic Ocean). The specimens of the new species were caught during the...     

Multivariate analyses of metrical features in the Lepidapedon elongatum (Lebour, 1908) species-complex (Digenea,Lepocreadiidae) in deep and shallow water gadiform fishes of the NE Atlantic

One hundred and eleven Lepidapedon elongatum-like worms from five gadiform fish species in the North Atlantic are compared using multivariate analyses of 22 metrical features. A principal component analysis followed by a discriminant analysis indicate multivariate morphological differences between worms in the different hosts. It is argued that the forms in the five host species, Gadus morhua, Onogadus argentatus, Trachyrhynchus trachyrhynchus, Coryphaenoides (Nematonurus) armatus and Lepidion eques, should be considered separate oioxenic species.     

New data reinforcing the taxonomic status of Lepidion eques as synonym of Lepidion lepidion (Teleostei,Gadiformes)

The Mediterranean morid codling Lepidion lepidion is thought to be endemic, yet its taxonomic distinctiveness from the morphologically similar and more wide-ranging Atlantic Lepidion eques is unresolved, and has been controversial since the beginning of the twentieth century. Despite the abundant taxonomic literature questioning the interspecific relationship between these taxa, their current status remains unchanged. To elucidate the differentiation of the specimens identified as L. lepidion and L. eques collected across much of their geographic ranges, the sequence divergence of the cytochrome oxidase I “DNA barcode” gene of the mitochondrial genome was evaluated. A network analysis indicates that the most observed haplotypes are common to both species throughout their Mediterranean and North Atlantic distribution areas. This molecular evidence suggests the absence of biogeographical barriers and is insufficient to support the different species designations, giving L. eques the taxonomic status of junior synonym of L. lepidion.     

A new species of parasitic copepod,Shiinoa bakeri (Shiinoidae), with a new host record for Shiinoa elagata Cressey

Summary A new species of Shiinoa parasitic on the nasal lamellae of Indian Ocean and western Atlantic lutjanid fishes is described. A new record of Shiinoa elagata, originally described from Pacific Elagatus bipinnulatus, is reported from western Atlantic Sphyraena barracuda from Belize. The new species described herein brings the total number of Shiinoa species described to four. The family Shiinoidae is redefined.     

Revision of genus Melamphaes (Melamphaidae). II. Multi-Raker species: M. polylepis, M. falsidicus sp. nova, M. pachystomus sp. nova, M. macrocephalus, M. leprus

The second part of the publication is devoted to the Melamphaes species (family Melamphaidae), which are characterized by 20 and more rakers on the first gill arch, by seven soft rays in the ventral fin, by absence of a temporal spine, by 14–15 rays in the pectoral fin, and by 11 abdominal vertebrae. M. polylepis is characterized by circumtropical range (Atlantic Ocean, Indian Ocean, western and central Pacific Ocean). Newly described species M. falsidicus is described from the northern Atlantic Ocean, where it was sampled between 34°N and 58°N. Before, this species was defined as M. microps. Another newly described species, M. pachystomus, is described along the Peruvian Coast. M. macrocephalus is redescribed. This species inhabits the eastern tropical Pacific Ocean (approximately between 30°N and 23°S). One of the studied specimens of M. macrocephalus was characterized by larger body size (SL = 128 mm) than was described before for this species. M. leprus is known currently by single findings from the eastern tropical Atlantic Ocean (between 11°N and 4°S). This species was also found in the samples obtain in the Gulf of Guinea.     

Genetic diversity and historical demography of Atlantic bigeye tuna (Thunnus obesus)

Bigeye (Thunnus obesus) is a large, pelagic, and migratory species of tuna that inhabits tropical and temperate marine waters worldwide. Previous studies based on mitochondrial RFLP data have shown that bigeye tunas from the Atlantic Ocean are the most interesting from a genetic point of view. Two highly divergent mitochondrial haplotype clades (I and II) coexist in the Atlantic Ocean. One is almost exclusive of the Atlantic Ocean whereas the other is also found in the Indo-Pacific Ocean. Bigeye tuna from the Atlantic Ocean is currently managed as a single stock, although this assumption remains untested at the genetic level. Therefore, genetic diversity was determined at the mitochondrial control region to test the null hypothesis of no population structure in bigeye tuna from the Atlantic Ocean. A total of 331 specimens were sampled from four locations in the Atlantic Ocean (Canada, Azores, Canary Islands, and Gulf of Guinea), and one in the Indian and Pacific Oceans, respectively. The reconstructed neighbor-joining phylogeny confirmed the presence of Clades I and II throughout the Atlantic Ocean. No apparent latitudinal gradient of the proportions of both clades in the different collection sites was observed. Hierarchical AMOVA tests and pairwise phi(ST) comparisons involving Atlantic Ocean Clades I and II were consistent with a single stock of bigeye tuna in the Atlantic Ocean. Population genetic analyses considering phylogroups independently supported gene flow within Clade II throughout the Atlantic Ocean, and within Clade I between Atlantic and Indo-Pacific Oceans. The latter result suggests present uni-directional gene flow from the Indo-Pacific into the Atlantic Ocean. Moreover, mismatch analyses dated divergence of Clades I and II during the Pleistocene, as previously proposed. In addition, migration rates were estimated using coalescent methods, and showed a net migration from Atlantic Ocean feeding grounds towards the Gulf of Guinea, the best-known spawning ground of Atlantic bigeye tuna.     

Deep-sea scavenging demersal fish fauna of the Nazaré Canyon system, Iberian coast, north-east Atlantic Ocean

A baited imaging lander was deployed six times in the Nazaré Canyon at depths from 909 to 4361 m during August 2005 to investigate the demersal scavenging fishes. Species observed and lander-derived abundance estimates were similar to previous data from the Porcupine Seabight and abyssal plain, north-east Atlantic Ocean.     

Plectorhinchus macrolepis (Actinopterygii: Haemulidae) in the western Atlantic Ocean

Morphometric measurements, meristic counts and DNA barcoding identified the presence of a biglip grunt Plectorhinchus macrolepis in the western Atlantic Ocean. As the species is endemic to the tropical eastern Atlantic Ocean and has not previously been reported in the western Atlantic Ocean, we discuss the possible means by which it might have dispersed to the western Atlantic Ocean. Even though this species is not considered established in Paranaguá Bay, we advocate monitoring of possible new individuals and other exotic fish species.     

Vertical distribution and seasonal abundance of Aglantha digitale (O.F. Muller) (Coelenterata: Trachymedusae) and other planktonic coelenterates in the northeast Atlantic Ocean

The vertical distribution and seasonal variability in abundanceof the hydromedusa Aglantha digitale (O.F. Müller) andother coelenterates from the north-east Atlantic Ocean are described.The coelenterates were abundant from May to September and reachedpeak numbers in June, July and September when concentrationof 40 individuals m^–1 were recorded. A. digitale numericallydominated the codenterate population and accounted for over80% of the dry weight biomass in hauls taken from 1971 to 1974.The data suggests a 2 month development period for this medusafrom egg to mature adult (8 mm) which supports previous publisheddata. During the growth of the medusa there were considerablechanges in the ratios of wet to dry weights. At a bell-heightof 1 mm the mean dry weight was 22% of mean wet weight and at8 mm the mean dry weight was 5% of mean wet weight; the percentagedecreased further in the largest specimens to 2% at 25 mm. Themajority of A. digitale occurred in the upper 100 m but in lateJuly the larger specimens extended their distribution to thelimit of sampling (500 m). The two most abundant siphonophores, Dimophyes arctica(Chun) and Nanomia cara A. Agassiz, werefound deeper than the main population of A. digitale. It issuggested that coelenterates could be an important source ofnitrogen for the development of the late bloom of phytoplanktonin the north-east Atlantic Ocean.     

A New Species of Snailfishes (Liparidae) of the Genus Careproctus from the Northern Slope of the Aleutin Basin (Bering Sea)

Journal of Ichthyology - A new species of snailfishes Careproctus schmidti sp. nov. from the northwestern part of the Bering Sea is described. The specimen was caught in the mesobenthal of the...