Leucon parasiphonatus,a new species (Crustacea: Cumacea: Leuconidae) from Antarctic waters

Six specimens ofLeucon parasiphonatus n. sp. were collected at depths ranging from 15 to 424 m in the vicinity of King George Island (South Shetland Islands, Antarctica) and the south eastern Weddell Sea.Leucon parasiphonatus belongs to the subgenusLeucon and differs from the other already known antarctic and Subantarctic species of the genus, in the absence of a serrated dorsomedian line and in the presence of a long pseudorostrum with several fine setae at its tip, surrounding the very long branchial siphon. The surface of the carapace is granulated; the carapace displays no teeth except for a few at its antero-lateral margin and at its ventral margin. The species most similar toLeucon parasiphonatus isLeucon siphonatus, reported from Mediterranean and North Atlantic waters.     

Hansenomysis anaramosae n. sp., a new suprabenthic mysid (Crustacea: Mysidacea: Petalophthalmidae) from the Bellingshausen Sea (Southern Ocean)

A new petalophthalmid mysid, Hansenomysis anaramosae n. sp., is described from specimens sampled with a suprabenthic sled in the Bellingshausen Sea (Southern Ocean). Hansenomysis anaramosae is clearly distinguishable from its closest congener, H. angusticauda Tattersall, by the carapace sculpturing, the rostrum produced into a spine-like process, the shape and armature of the antennal scale, eyeplate, and telson. This new species is the fourth Hansenomysis species described from the Southern Ocean. A key to these Antarctic species is presented.     

FOUR NEW SPECIES OF THRAUSTOCHYTRIUM FROM ANTARCTIC REGIONS,WITH NOTES ON THE DISTRIBUTION OF ZOOSPORIC FUNGI IN THE ANTARCTIC MARINE ECOSYSTEMS

New species of the obligately marine Thraustochytriaceae Sparrow were discovered in subantarctic and antarctic waters of the southeastern Indian Ocean, the southwestern Pacific Ocean, and the antarctic Ross Sea during two cruises of the research vessel USNS ELTANIN. The life cycles of four species of Thraustochytrium in seawater-pollen and/or seawater-brine shrimp larvae cultures are described. Thraustochytrium antarcticum sp. nov. develops sporangia that may proliferate from a single basal rudiment. Flagellated zoospores are liberated from the sporangium upon complete disintegration of the sporangial wall at maturity. Thraustochytrium rossii sp. nov. and T. kerguelensis sp. nov. are both similar in that they develop sporangia that may proliferate from more than one basal rudiment. The latter species releases flagellated zoospores upon complete disintegration of the sporangial wall, but the former species liberates a mass of individually immobile zoospores from the sporangium. These remain quiescent for several hours before they swim away one after another. The protoplast of Thraustochytrium amoeboidum sp. nov. leaves the sporangium through a pore as an amoeboid body which then gives rise to nonflagellated amoebospores by successive bipartitioning. Laterally biflagellate thraustochytrioid zoospores were also observed, but the way in which they are formed remains to be determined. Zoosporic and aplanosporic phycomycetes were recovered from water samples collected in the Subtropical, Subantarctic, and Antarctic Zones of the Southern Ocean. Highest numbers of phycomycete propagules were found in antarctic waters near the Antarctic Convergence during ELTANIN's Cruise 51. In the Subtropical and Subantarctic (but not in the Antarctic) Zones fungal population densities increased with proximity to continents or islands. At each station where phycomycetes were recovered, highest numbers of propagules were generally found in the surface layers (25–250 m) of the ocean below the photic zone (lower limit 30–60 m). This peculiar distribution may indicate that phycomycetes are engaged in decomposing substances derived from the photic zone.     

Two species of swimming crabs of the genus Achelous (Crustacea,Brachyura): environmental requirements determining the niche

Some holoplanktonic species are cosmopolitan and have continuous distribution in the world’s oceans. For most of these species it is not clear whether there is unhampered gene flow between far distant populations or they represent a complex of cryptic species. In the present study we investigated genetic diversity of the cosmopolitan chaetognath Eukrohnia hamata in order to identify its spatial structure. DNA-barcode fragment of the mitochondrial COI gene was determined and analyzed for E. hamata specimens collected in the Arctic Ocean, Atlantic Ocean, and Atlantic sector of the Southern Ocean. Five lineages were determined by the phylogenetic analysis with robust statistical support. Three lineages: Antarctic (Eh-1), Subantarctic (Eh-2), and Arctic (Eh-3) had significant genetic differences and were geographically separated. Two other lineages: Eh-4 and Eh-5, that had the smallest genetic difference, were observed together in tropical waters, but they were geographically separated from the other lineages. We suppose that geographical distribution of most of the E. hamata lineages is shaped by the large-scale oceanic fronts, considered as biogeographic boundaries for numerous zooplankton species. Genetic homogeneity of Arctic, Subantarctic, and Antarctic lineages was also shown, each within its regions of inhabit.     

Additions to the knowledge on fossil rodents of Uruguay (Mammalia: Rodentia)

Additions to the knowledge on fossil rodents of Uruguay (Mammalia: Rodentia). — This paper brings new information on fossil rodents of Uruguay. Four new species are described:Microcavia (M.) aua n. sp. (Caviidae),Ctenomys mesorhinus n. sp. (Octodontidae),Isostylomys intermedius n. sp. andIsostylomys magnus n. sp. (Dinomyidae), the latter from Argentina. Apart from this,Palmiramys waltheri Kraglievich, 1932, illustrated here for the first time, is considered a Lower Oligocene (Deseadan) ?Dasyproctidae. The first records for Uruguay ofEucardiodon cf.marshi (Ameghino) (Hydrochoeridae), and +Holochilus brasiliensis (Desmarest) are reported.     

Two new species ofTrichogramma [Hym.: Trichogrammatidae] from the U.S.A.

Two new species ofTrichogramma from the U.S.A. are described.T. parkeri sp. n., a morphologically distinct species, was reared from an egg ofHeliothis zea (Boddie), whileT. platneri sp. n. which is morphologically indistinguishable fromT. minutum Riley, was reared from eggs ofCydia pomonella (L.). Reproductive incompatibility ofT. platneri andT. minutum is discussed.     

The development of planktonic biogeography in the Southern Ocean during the Cenozoic

Deep-sea drilling at high latitudes of the Southern Hemispheres has provided almost the only available data to evaluate the biogeographic development of the planktonic biota in the Southern Ocean during the Cenozoic (65 m.y. to Present Day). Paleontological investigations on Deep Sea Drilling Project (DSDP) materials have shown that the development of Cenozoic planktonic biogeography of the Southern Ocean is intimately linked with the evolution of the Southern Ocean water masses themselves. During the Cenozoic, this has included the development of the Circum-Antarctic Current system as obstructing land masses moved apart, the refrigeration and later extensive glaciation of the continent, and the development of the Antarctic Convergence (Polar Front) with related oceanic upwelling.Almost all evolution of calcareous planktonic microfossils has occurred outside of the Antarctic—Subantarctic region followed by limited migration into these water masses. Virtually no endemism occurs amongst calcareous microfossil groups at these latitudes. In contrast, conspicuous and widespread evolution has occurred within the siliceous microfossil groups especially during the Neogene. Low diversity and differences in stratigraphic ranges of Antarctic calcareous microfossils makes them only broadly useful for correlation. Relatively higher diversities within the Subantarctic provide a firmer basis for more detailed correlation, although the ranges of fossils are often different than at lower latitudes because of different paleoceanographic and paleoclimatic controls. Within the Antarctic water mass south of the Antarctic Convergence, siliceous microfossilsbiostratigraphy, oxygen isotopic stratigraphy and magnetostratigraphy, provide the only firm basis for correlation with low-latitude sequences.Eocene (55-38 Ma) sediments contain abundant calcareous microfossils even closely adjacent to the continent. Antarctic calcareous planktonic microfossils of this age exhibit relative high diversity, although this is lower than assemblages of equivalent age at middle and low latitudes. Within the Subantarctic region, Eocene planktonic foraminifera exhibit strong affinities with those in the temperate regions. Biogeographic differences exist between various sectors of the Southern Ocean related to biogeographic isolation preceding the development of the Circum-Antarctic Current. Subantarctic calcareous nannofossil assemblages of Paleocene and Eocene age exhibit higher diversity than Oligocene and Neogene assemblages. Siliceous microfossils are poorly represented or at best poorly known.One of the most dramatic changes in Southern Ocean planktonic biogeography occurred near the Eocene/Oligocene boundary (38 Ma). Since then, Antarctic planktonic foraminiferal assemblages have exhibited distinct polar characteristics, marked in particular by low diversity, and this event thus reflects the initiation of the Antarctic faunal and floral provinces. Profound paleoceanographic changes at this time, which triggered the biogeographic crisis, appear to be related to the initiation of widespread Antarctic sea-ice formation, and rapid cooling of deep and intermediate waters, in turn associated with increased Antarctic glaciation. During the Oligocene, planktonic microfossil diversity was low in all groups throughout the world's oceans. In Antarctic waters, the early Oligocene foraminiferal fauna is monospecific (Subbotina angiporoides), while in the later Oligocene two species (S. angiporoides and Catapsydrax dissimilis) were recorded. Calcareous nannofossil assemblages are of low diversity compared with the Eocene. Subantarctic foraminiferal faunas of Oligocene age display much higher diversity than those in the Antarctic, but early and middle Oligoceae faunas still exhibit the lowest diversities for the entire Cenozoic. Siliceous assemblages remain relatively inconspicuous in most regions of the Southern Ocean.The Paleogene-Neogene transition (22 Ma) is marked by a major change in the global planktonic biogeography, i.e. modern patterns developed in which permanent, steep faunal and floral diversity gradients existed between tropical and polar regions; a gradient which has persisted even during the most severe glacial episodes. Oligocene assemblages of low diversity and almost cosmopolitan distribution were replaced by distinctive belts of planktonic assemblages arranged latitudinally from the tropics to the poles. The establishment of the steep planktonic diversity gradients and latitudinal provinces near the beginning of the Neogene almost certainly were linked to the development of the Circum-Antarctic Current in the late Oligocene which effectively separated high- and low-latitude planktonic assemblages. These fundamental global circulation and biogeographic patterns have persisted through the Neogene.During the Neogene (22 Ma to Present Day), Antarctic calcareous microfossil assemblages exhibit persistent low diversity and high dominance, while Subantarctic assemblages are of much greater diversity. The beginning of the Neogene (= beginning of Miocene) heralded the development of the high-latitude siliceous microfossil assemblages towards their present-day dominant role. Siliceous biogenec productivity began to increase. These changes were linked to the initial development and later intensification of circulation associated with the Antarctic Convergence and Antarctic Divergence. The Antarctic Convergence sharply separates dominantly siliceous assemblages to the south from calcareous assemblages to the north. Radiolarian assemblages became more endemic. Relatively warm early and middle Miocene conditions are reflected by slightly higher diversity of planktonic foraminifera and by the presence, in the northern Subantarctic, of conspicuous discoasters in early Miocene sediments. In Antarctic waters, calcareous nannofossils become unimportant as biogenic elements after the middle Miocene.The latest Miocene ( 5 m.y. ago) was marked by northward movement of the Antarctic Convergence, corresponding expansion of the Antarctic water mass, and low diversity of calcareous assemblages. Pliocene planktonic foraminifera seem to be largely monospecific in Antarctic and southern Subantarctic sequences. During the Quaternary, Antarctic waters reached a maximum northward expansion and exhibit highest siliceous biogenic productivity for the Cenozoic. In the Subantarctic, Quaternary foraminiferal diversities are much higher than in Pliocene sequences. Although calcareous nannofossil diversity may be high, only a few species are abundant. Large northward shifts of Antarctic and Subantarctic water masses have occurred during the Quaternary although no southward penetrations have occurred much beyond that of the present day. Several radiolarian and foraminiferal species disappeared or appeared at or close to a number of paleomagnetic reversals during the last 4 m.y. These faunal events, which provide valuable datums, do not seem to be associated with major climatic changes.     

Physical and biological coupling in eddies in the lee of the South-West Indian Ridge

Eddies have some decisive functions in the dynamics of the Southern Ocean ecosystems. This is particularly true in the Indian sector of the Southern Ocean, where a region of unusually high-mesoscale variability has been observed in the vicinity of the South-West Indian Ridge. In April 2003, three eddies were studied: eddy A, a recently spawned anticyclone south of the Antarctic Polar Front (APF),; eddy B, an anticyclone north of lying between the Subantarctic Front and the APF; and eddy C, a cyclone north of the APF west of the ridge. Elevated concentrations of total Chl-a coincided with the edges of the cyclonic eddy, whereas both anticyclonic eddies A and B were characterised by low total Chl-a concentrations. Biologically, the two anticyclonic eddies A and B were distinctly different in their biogeographic origin. The zooplankton community in the larger anticyclonic eddy A was similar in composition to the Antarctic Polar Frontal Zone (APFZ) community with an addition of some Antarctic species suggesting an origin just north of the APF. In contrast, the species composition within the second anticyclonic eddy B appeared to be more typical of the transitional nature of the APFZ, comprising species of both subantarctic and subtropical origin and thus influenced by intrusions of water masses from both north and south of the Subantarctic Front. Back-tracking of these features shows that the biological composition clearly demarcates the hydrographic origin of these features.     

<Emphasis Type="Italic">Campylonotus arntzianus</Emphasis>, a new species of the Campylonotidae (Crustacea: Decapoda: Caridea) from the Scotia Sea (Antarctica)

Two specimens of Campylonotus arntzianus sp. nov. were caught in the Antarctic Scotia Sea off Saunders Island (57°40.31'S, 26°27.81'W) using an Agassiz trawl at one station (depth: 475-589 m). The new species described here is the fifth representative of the monogeneric family Campylonotidae, and the first of the family south of the Antarctic Convergence. Campylonotus arntzianus sp. nov. is a shrimp of about 5 cm in total length. Due to similarities in adult morphology, C. arntzianus sp. nov. seems to be closely related to C. capensis, a deep-sea species from the Southern Atlantic Ocean. A simple key for the species identification of the Campylonotidae is provided.     

Vertical Distribution of Pelagic Ostracods (Ostracoda,Halocyprinidae) in the Australian–New Zealand Sector of the Southern Ocean

Samples of plankton from the Australian–New Zealand sector of the Southern Ocean have been examined. A species list of pelagic fauna of ostracods is presented including latitudes and depths for Antarctic and Subantarctic water structures and the neighboring subtropical regions. The vertical distribution of ostracods is studied in the waters of the Subantarctic and Antarctic.     

Two new species of Ammothea (Pycnogonida, Ammotheidae) from Antarctic waters

Two new species of the genus Ammothea are described from Elephant Island and the South Shetlands Islands, Antarctica. The material was captured during the Polarstern cruise XXIII/8 to the Antarctic Peninsula area. The main features of Ammothea pseudospinosa n. sp. are a proboscis distinctly trilobulated distally with a constriction at 2/3 of its length and dimorphism between the propodi of the anterior (first and second) and posterior (third and fourth) legs, and a trunk: proboscis length ratio of about 1.5. The main features of Ammothea childi n. sp. are a cylindrical proboscis, longer than trunk length, and adults with functional chelifores. These species are compared with their closest congeners from the Southern Ocean: A. pseudospinosa n. sp. with Ammothea spinosa and Ammothea allopodes; A. childi n. sp. with Ammothea gigantea, Ammothea bicorniculata and Ammothea hesperidensis.     

New species of pelagic eelpouts of the genus <Emphasis Type="Italic">Melanostigma</Emphasis> (Zoarcidae) from Western Antarctica

A new species, Melanostigma olgae sp. n., is described from the Southern Ocean. The type series was obtained along the South Sandwich Islands (Scotia Sea, Western Antarctic) at the depths of 800?850 m. The new species differs from the other representatives of Melanostigma genus by the original combination of the features of the seismosensory system, axial skeleton, and coloration. The homologization of the structural elements (senses) of the head canals of the lateral line has been done for the first time for the Melanostigma. Morphology of M. olgae allows considering this species as the most evolutionary advanced within the representatives of this genus inhabiting the Southern Ocean. The key of the Antarctic species of the genus Melanostigma is provided.     

Studien über die Branchiosauridae (Amphibia: Temnospondyli) 1. Neue und wenig bekannte Arten aus dem mitteleuropäischen Rotliegenden (?oberstes Karbon bis unteres Perm)

As part of a review of the Branchiosauridae some recently discovered specimens from the Rotliegend of the Saar-Nahe-Basin and rediscovered material from the Rotliegend of northern Saxony are described. One of the Saar-Nahe specimens is designated the neotype ofApateon pedestris Meyer 1844. This species replacesProtriton petrolei Gaudry 1875. One of the northern Saxony specimens is chosen as the lectotype ofLeptorophus tener (Schonfeld 1909). This species is redescribed. Two new species are described and named:Scboenfelderpeton prescheri n. gen. n. sp. andApateon dracyiformis n. sp. The former is remarkably differentiated in respect to its otic notch. The latter is very similar toApateon dracyi (Boy 1972). The northern Saxony locality not only contains Branchiosauridae but also the micromelerpetontidBrancbierpeton. The palaeoecology of this fauna is discussed.     

A new species of Mysella Angas, 1877 (Bivalvia: Galeommatoidea) from Admiralty Bay, King George Island, South Shetlands, Antarctica, with data on its biology and functional anatomy

Mysella narchii sp. nov. is described from the material collected in shallow-waters of Admiralty Bay at King George Island, South Shetlands, Antarctica. The species is characterized by shell features, biology and functional anatomy. The main shell features distinguishing M. narchii sp. nov. from all other Antarctic, Subantarctic and Magellanic Mysella spp. are provided, as are anatomical characteristics that separate this new species from M. charcoti (Lamy, 1906), its most similar congener and the first Antarctic species studied in its morpho-functional aspects. M. narchii sp. nov. is an infaunal, free-living, predominantly deposit-feeding bivalve; its creeping sole and the secretion of byssal threads allow it to crawl vertically and live sporadically on firm substrata.     

Distribution and community structure of pelagic shrimps in the Southern Ocean between 150° E and 115° E

Summary Geographical distribution of biomass and species, community structure, and size comparisons of pelagic shrimps were investigated in the upper 1000m in the Southern Ocean between 150° E and 115° E during the austral summer (December 1985 and January 1986). The biomass ranged from 0 to 4.25 g wet weight/1000 m³ collected by the IKMT and in general tended to decrease southward. The average biomass north of the Polar Front and in the Antarctic Zone was 2.55 and 0.40 g/1000 m³, respectively. Twenty species were collected and of these eight were in the Antarctic Zone. Pelagic shrimps in the study area were assigned to four categories by their geographical distribution. The first included five upper meso-pelagic species and was restricted to the Subtropical Zone. The second included seven lower meso-pelagic species and occurred in the Subtropical and Subantarctic Zones. The third included seven lower meso-and bathy-pelagic species and was distributed from the Subtropical Zone to the Antartic Zone. The fourth category of one species was distributed from the Subantarctic Zone to the Antarctic Zone. We suggest that oceanic fronts in the study area do not constitute a distributional barrier to lower meso-and bathy-pelagic shrimps.     

Synopsis of the pycnogonids from Antarctic and Subantarctic waters

This work summarizes existing knowledge on the faunal history, biodiversity and biogeography of the Antarctic and Subantarctic pycnogonids. It refers to material sampled between 1829 and 1999 from more than 40 expeditions run by 14 countries, and published in 75 papers. Up to now, 31 genera and 25 species have been recorded from a total of about 38,000 specimens captured at 2,000 stations. They constitute 38.75% and 21.5%, respectively, of the 80 genera and 1,164 species recorded worldwide. One hundred and twenty species have been found in Antarctic, 71 in Subantarctic waters, and 60 species in both zones, yielding an endemicity for the entire area of over 80%. Fifty five species revealed a circumpolar distribution and 161 were found mainly on the shelf. The Antarctic Ocean is suggested to be a centre of pycnogonid speciation and dispersion.     

Latitudinal Distribution of Pelagic Ostracods (Ostracoda,Halocyprinidae) in the Australian–New Zealand Sector of the Southern Ocean

The latitudinal distribution of ostracods between the Subtropical Convergence and Antarctic Divergence has been studied from the example of materials from the Australian–New Zealand sector of the Southern Ocean. The biogeographical structure of ostracod fauna has been revealed in the Subantarctic and Antarctic. Species-indicators have been distinguished for Antarctic and Subantarctic waters.     

Three new species of the genus Leucon Kröyer, 1846 (Crustacea: Cumacea) from the continental slope off Surinam

Three new, and apparently closely related, species of cumacean are described from the continental slope off Surinam: Leucon turgidulus sp.nov. from about 500 m depth, L. medius sp.nov. from about 1000m and about 1500m, and L.jonesi sp.nov from about 1500m and about 2000m. The species have not been found in extensive collections from other parts of the deep Atlantic. Leucon pallidus G.O. Sars, 1865 is the most closely comparable of the previously known members of the genus.