THE DISTRIBUTION OF SOME ENDEMIC ANTARCTIC NUDIBRANCHIA

The distribution of six endemic Antarctic nudibranch speciesis described, using both published data and new results fromrecent expeditions to the Atlantic sector of the South PolarSea. Notaeolidia schmekelae Wägele, 1990 is restrictedto the Weddell Sea, and N. gigas Eliot, 1905 to the AntarcticPeninsula and the Scotia Arc. N. depressa Eliot, 1905 is theonly member of the family Notaeolidiidae Odhner, 1926 with acircumpolar distribution. Localities of Pseudotritonia quadrangularisThiele, 1912 and Telarma antarctica Odhner, 1934, are knownaround the Antarctic Continent, whereas Pseudotritonia gracilidensOdhner, 1944 was only collected at the Antarctic Peninsula.The biogeographical divisions, discussed by several authors,do not coincide in all aspects with the distribution patternsof the Nudibranchia. According to my results, the AntarcticPeninsula forms a separate faunal zone, with transitional elementsof the High Antarctic and Subantarctic zone. South Georgia hasno endemic nudibranchs. (Received 30 March 1990; accepted 23 September 1990)     

Life cycle strategies and seasonal variations in distribution and population structure of four dominant calanoid copepod species in the eastern Weddell Sea, Antarctica

The dominant Antarctic copepod species Calanoides acutus, Calanuspropinquus, Rhincalanus gigas and Metridia gerlachei were investigatedwith respect to their abundance, vertical distribution, developmentalstage composition, dry weight and lipid content. The specimenswere sampled during three expeditions to the eastern WeddellSea in summer (January/February 1985), late winter/early spring(October/November 1986) and autumn (April/May 1992) between0 and 1000 m depth to follow the seasonal development of thepopulations. Three species were most abundant in April, onlyC.propinquus reached highest concentrations in February. A seasonalmigration pattern was evident in all four species, but was mostpronounced in C.acutus. In October/November, they inhabiteddeeper water layers, their ascent started by mid-November andin mid-February the species concentrated in the upper 50 m,except for M.gerlachei (50–100 m). Their descent was observedin April/May. The stage composition changed dramatically withseason, the older developmental stages (CIII–CVI) dominatedthe populations in late winter/early spring, whereas youngerstages (CI and CII) prevailed during summer (C.acutus, C.propinquus)or autumn (R.gigas, M.gerlachei). Only C.acutus ceased feedingin autumn and diapaused at depth. Strong differences betweenseasons were also detected in dry weight and lipid levels, withminima in late winter/early spring and maxima in summer (C.acutus,R.gigas) or autumn (C.propinquus, M.gerlachei). Lipid reservesseem to be most important for the older stages of C.acutus andC.propinquus. Based on these seasonal data, different life cyclestrategies are suggested for the four species.     

The occurrence of Rhincalanus gigas,Calanoides acutus,and Calanus propinquus (Copepoda: Calanoida) in late May in the area of the Antarctic Peninsula

Summary The Antarctic copepod species Rhincalanus gigas, Calanoides acutus and Calanus propinquus were studied in the area of the Antarctic Peninsula in May 1986. Research was focussed on vertical distribution and stage composition of the populations. Rhincalanus gigas occurred in greatest densities in the upper layers of the water column, and copepodite stages CI and CII and nauplii dominated the population. Gut content analyses suggest that R. gigas was actively feeding. Copepodite stage CV dominated the Calanoides acutus population. At two deep basin stations (water depth>1000 m) the C. acutus population occurred below 500 m, whereas at shallower stations the majority was found above 300 m. Most specimens had empty guts. Calanus propinquus occurred in low densities, mainly in the upper water layers, and copepodite stage CV dominated. Most individuals of stage V had food in their guts. Our results suggest that C. acutus had ceased feeding and was overwintering in a resting stage (diapause), while C. propinquus and R. gigas were still active, the latter species having finished a late autumn spawning.     

Ecophysiology of Niche Occupation by Two Giant Rosette Plants, Lobelia gibberoa Hemsl and Solanecio gigas(Vatke) C. Jeffrey, in an Afromontane Forest Valley

The niche occupation of two giant rosette plants, Lobelia gibberoaHemsl and Solanecio gigas(Vatke) C. Jeffrey, was investigatedin a small mountain valley in an afromontane forest, centralEthiopia. Plant distribution, density, life-form, morphologyand microsite conditions were related to transpiration, chlorophylla fluorescence and ¹³C analysis to explain how ecophysiologicaltraits and morphology determine the niche differentiation ofplants of similar life-forms. L. gibberoa was more abundantat the humid northern flank of the valley while S. gigas wasequally distributed in the northern and drier southern flanks;both species occurred in the valley bottom. Photosynthetic capacity,as determined by chlorophyll a fluorescence, was similar forboth species. In dry locations, S. gigas transpired somewhatless and had lower leaf conductance for water vapour, g, than in wet locations. Both specieshad the highest gand ¹³C-isotopediscrimination in the wettest locations. Overall for the ecophysiologicaltraits, site differences were larger than differences betweenthe two species. L. gibberoa had a well developed vascular cylinder,maintained a large number of rosettes and had an average leafarea index (LAI) of 2.8, which may restrict it to the more humidlocations. S. gigas, with a poorly developed vascular bundle,had many fewer rosettes, an average LAI of 1.5, and reactedmore to the water status of its habitat. It was thus also capableof colonizing drier locations. The role of morphological andanatomical traits and ecophysiological features in niche occupationas revealed by assessment of vegetation is discussed. Copyright2001 Annals of Botany Company Life forms, Lobelia gibberoa, afromontane forest, niche occupation, Solanecio gigas     

HYDROBIIDAE (GASTROPODA: HYDROBIOIDEA) FROM THE RIBEIRA VALLEY, S.E. BRAZIL, WITH DESCRIPTIONS OF TWO NEW CAVERNICOLOUS SPECIES

Potamolithus karsticus n. sp. and Potamolithus troglo-bius n.sp., two Brazilian aquatic cavesnails (Gastropoda: Hydrobiidae),are described. P. troglobius is blind and depigmented, and isthe first stygobiontic snail to be described from Brazil Additionally, specimens of Potamolithus ribeirensis Pilsbry,1911 were collected near the type locality for comparison withthe new cave species (Received 2 December 1993; accepted 20 June 1994)     

Seasonal Variation in Respiratory and Photosynthetic Parameters in Three Mosses from the Maritime Antarctic

Carbon fixation under controlled conditions was measured inthree mosses from the maritime Antarctic using an infra-redgas analysis system. Gas exchange parameters were determinedduring each season in 1993 and 1994 using the Arrhenius equationand a hyperbolic tangent function applied to respiration andphotosynthesis, respectively. Environmental data was collectedin 1994 for comparison. All seasonal variations were greaterinBrachythecium than in the species from less hydric habitats.Respiration rates were highest in summer and lowest in winterat all temperatures inBrachythecium, but there was little changeinChorisodontium orAndreaea . There was some seasonal variationin the initial slope (K_p) of the photosynthesis-irradiance curvein all species, although the environmental data suggested thatthis was of little ecological importance. In all species seasonalchanges in the maximum rates of photosynthesis (GP_max, NP_max)were observed, generally with a pattern of summer maxima, althoughthere were some interannual differences. These changes are consideredto be the most important in affecting the overall annual productivityof the mosses. There were no seasonal variations in the optimumtemperatures for either gross or net photosynthesis, or forthe irradiance at the onset of light saturation (I_k). The resultshave important implications for the use of models to estimatethe productivity of the Antarctic flora based upon present orpredicted climate data. Antarctica; bryophytes; mosses; carbon exchange; irradiance; photosynthesis; productivity models; respiration; seasonal variation; temperature     

SYSTEMATIC REVISION OF PATELLOIDA PYGMAEA (DUNKER, 1860) (GASTROPODA: LOTTIIDAE), WITH A DESCRIPTION OF A NEW SPECIES

Patelloida pygmaea (Dunker) and its closely allied species,P. heroldi (Dunker) and P. conulus (Dunker) have caused nomenclaturalconfusion because of their variable shell morphology and distinctivehabitats. According to current nomenclature, these species ofPatelloida have been synonymized and treated as one specieswith two ecological forms. Patelloida pygmaea lives on the shellof Crassostrea gigas (Ostreidae), P. pygmaea form heroldi occurson intertidal rocks on sheltered shores and P. pygmaea formconulus is found on the shell of Batillaria multiformis (Batillariidae).Their taxonomic relationships and possible species status are,however, unclear. Using two mitochondrial genes (fragments ofCOI and 16S ribosomal RNA; total 1192 sites), we analysed 88specimens of P. pygmaea, P. pygmaea form heroldi and P. pygmaeaform conulus from 37 localities in East Asia. In the resultingmolecular phylogenetic trees, the specimens of Patelloida fallinto four clades with high bootstrap probabilities; these cladescorrespond taxonomically to P. pygmaea, P. conulus, P. heroldiand a fourth previously unrecognized taxon, Patelloida ryukyuensisn. sp., described here. A minimum-spanning network for 29 uniquemitochondrial COI haplotypes obtained from 45 specimens in thesame bay in central Japan form three distinct clusters, consistingof P. pygmaea, P. conulus and P. heroldi, respectively. Thissuggests that reproductive isolation has been established betweeneach group. A detailed examination of radular and shell morphologiesof the four taxa clarifies the morphological distinction betweenthese species. The four species form a rather young clade inthe genus Patelloida that diverged during the Pliocene. Theyprovide an example of habitat segregation in a restricted marineenvironment. (Received 21 December 2004; accepted 11 March 2005)     

DISTRIBUTION AND PRODUCTION OF THREE HYDROBIA SPECIES (GASTROPODA: HYDROBIIDAE) IN A SHALLOW COASTAL LAGOON IN THE BAY OF CADIZ, SPAIN

The abundance, life span, growth and production of the mud snailsHydrobia minoricensis, H. ulvae and H. ventrosa in a semi-naturallagoon system were studied by taking monthly samples at threesites during 1991 and 1992. The most abundant species, H. minoricensisoccurred at mean densities of 12834 to 26264 snails m^–2(10.7 to 25.8g dry weigh m^–2), depending on the site.The least abundant species, H. ulvae, occurred at mean densitiesof 185 to 353 snails m^–2 (3.2 to 2.2g dry weight m^–2).The numerical abundance and biomass of the three Hydrobia specieswere positively related to the biomass of benthic macroalgae(P<0.01). Although H. ulvae egg capsules were recorded throughoutthe year, newly hatched snailsof this species were not observed,in contrast to the other two species. The early spring and summercohorts of H. minoricensis and H. ventrosa seemed to be themost numerous. The average life spans of these two species wereestimated to be about 18 and 13 months respectively. Annualproduction estimates for the whole lagoon system were 29.0 (6.3),5.5 (0.8) and 5.2 (1.0)g dry weight (ash-free dry weight) m^–2yr^–1 for H. minoricensis, H. ulvae and H. ventrosa respectively.The annual P/B ratio was about 2 for H. minoricensis and H.ventrosa. (Received 5 July 1994; accepted 5 October 1994)     

ANATOMY OF SOME PILL CLAMS (BIVALVIA: PISIDIOIDEA) FROM AFRICA, WITH THE DESCRIPTION OF NEW TAXA

The anatomy of 4 species of pisiid clam sampled in Ethiopia,Zimbabwe and South Africa was studied. The new species Pisidiumethiopicum is described, including the Ethiopian form regardedearlier as a variety of P. casertanum (Poli). P. incomitatumKuiper is included in the genus Musculium as type species ofa new subgenus Pseudopisidium. Anatomical characters of PisidiumkenianumPreston and P. langleyanum Melvill & Ponsonby arealso discussed. (Received 22 March 1994; accepted 23 August 1994)     

Revision of the Antarctic genus Notaeolidia (Gastropoda, Nudibranchia), with a description of a new species

New material from the Atlantic sector of the Antarctic Ocean allows a revision of the Antarctic genus Notaeolidia Eliot, 1905. One new species (Notaeolidia schmekelae sp.n.) is described. N. depressa Eliot, 1905 and N. gigas Eliot, 1905, which arc poorly known, arc redescribed. N. rufopicta Thiele, 1912, N. robsoni Odhner, 1934, N. subgigas Odhner, 1944, N. alutacea Minichev, 1972 and N. flava Minichev, 1972 are synonymized with N. depressa. N. purpurea Eliot, 1905 is synonymized with N. gigas. The monogeneric family Notaeolidiidae Odhner, 1926. is characterized by the following autapomorphy: "nephroproct in front of the genital apertures". Too little is known to elaborate the phylogenetic position of the family Notaeolidiidae within the cladobranch Nudibranchia.     

TWO NEW SPECIES OF THE GENUS ISLAMIA RADOMAN, 1973 FROM ITALIAN ISLANDS (PROSOBRANCHIA, HYDROBIIDAE)

Two new Italian species of the genus Islamia (Prosobranchia:Hydrobiidae), one living in eastern Sicily (I. cianensis), andone on Elba Island (Tuscan Archipelago, Italy) (I. gaiteri)are described. The two species are distinguished on the basisof shell and anatomical characters, mainly those of the malegenitalia. I. cianesis n. sp. is characterized by a valvatoidshell and a penial lobe with internal band of glandular tissuenot distinct in its lower portion from the penis body but bulgingapically as a small knob. I. gaiteri n. sp. is characterizedby a planispiral shell and a small lateral penial lobe withoutinternal glandular tissue. (Received 20 December 1993; accepted 27 June 1994)     

Gut evacuation rates of Antarctic copepods during austral spring

The results of gut evacuation experiments performed on Antarctic copepods during the austral spring are presented and discussed. Four species of large copepods commonly occurring in the Indian sector of the Antarctic Ocean were studied: Calanus propinquus, Calanoides acutus, Rhincalanus gigas and Pleuromamma robusta. For each species two experiments were carried out, one in daytime and one in night-time, except for Calanoides acutus, which was only studied at night. P. robusta showed pigment gut retention in all experiments. The results showed that all species studied had a longer gut passage time than that previously recorded and that gut evacuation rate appears to decrease during daytime. Accepted: 1 October 1998     

SOME OBSERVATIONS ON THE DIET AND DISTRIBUTION OF NUDIBRANCHS AT SIGNY ISLAND, ANTARCTICA

Observations were made on the diet and distribution of eightspecies of nudibranchs found in Borge Bay, Signy Island, Antarctica.Specimens from seven sites were examined in situ on four separateoccasions during 1992 and 1993 using SCUBA. A small collectionfor identification was also made Six of the eight species presentwere identified, and the first ecological data for at leastone species (Charcotia granulosa) were recorded. Notaeolidiagigas was feeding principally on hydroids of the genus Tubulariaover the entire depth range surveyed (3–36 m), and wasmost abundant in shallow water, whereas Truomella belli wasonly found at deeper sites, mostly on an octocoral of the genusAscolepis. Charcoaa granulosa and Pseudotritoma gracilidensappeared to be specialist bryozoan feeders and, as has beenfound at other locations, Austrodoris kerguelenesis specialisedon the demosponge Dendnlla antarcnca. Two unidentified aeolidspecies occurred almost entirely on particular hydroids andthe prey of Tritonia antarctica was not apparent. The physicalsize of Antarctic nudibranchs may have important implicationsto the type of prey and feeding strategy used by different species. (Received 11 May 1995; accepted 3 December 1995)     

CADMIUM, LEAD AND COPPER IN FRESHWATER MUSSELS FROM THE ASSINIBOINE RIVER, MANITOBA, CANADA

Cadmium, lead and copper levels were examined in adductor muscle,foot, gonad, mantle, gill, and heart of 9 species of freshwatermussels from the Assini-boine River, using anodic strippingvoltametry. Metal levels in most organs were lower than in bottomsediments. The metals generally showed significantly higherconcentrations in heart and hemolymph samples than in the othertissues examined. However in four species, gill tissues showedthe highest values forcopper, and Quadrula quadnda and Ligumiarecta accumulated the greatest amounts of copper overall. Cadmiumconcentrations were particularly high in heart and hemolymphof Lampsilis radiata sili-quoidea, L. vcntricosa, and Ligumiarecta. Metal concentrations in tissues of a given species showedvarious relationships to weight of soft parts, shell length,and shell weight, but inverse correlations predominated, indicatingthat metals in many organs were less concentrated in older individuals.In L. radiatasiliquoidea and L. vcntricosa, copper concentrationswere higher in males than in females. Lead levels were alsohigher in L. vcntricosamales. (Received 24 June 1994; accepted 8 September 1994)     

THE DISTRIBUTION OF SOME ANTARCTIC NUDIBRANCHS (OPISTHOBRANCHIA)

The circumpolar distribution of the four revised species ofdoridacean nudibranchs: Aegires albus, Bathydoris hodgsoni,B. clavigera and Austrodoris kerguelenensis, is demonstrated,taking into consideration the known data from the literatureand new localities from the Atlantic sector of the Antarctic.A. albus and B. hodgsoni are restricted to the High AntarcticZone. A. kerguelenensis is widely distributed in the High Antarcticand Subantarctic Zone, whereas localities of B. clavigera arerestricted to the High Antarctic Zone and the Atlantic sectorof the Subantarctic Zone. (Received 13 November 1986;     

Cumaceans (Crustacea) from the Bellingshausen Sea and off the western Antarctic Peninsula: a deep-water link with fauna of the surrounding oceans

During the austral summers of 2003 and 2006, two cruise were carried out in the Bellingshausen Sea and west off Antarctic Peninsula on board of RV Hespérides. Samples were collected at 26 stations with a multinet Macer-GIROQ sled. A total of 557 cumaceans belonging to 36 species of five families were collected. Nannastacidae was the most abundant and speciose family. Hemilamprops pellucidus and Cyclaspis gigas were the most frequently collected species (38.5% of sampling stations). Cumella asutralis reached the highest density (514.7 individuals/1,000 m² at stn 7). Maximum species richness (S = 15) and diversity (H′ = 3.53) was observed at one of the deepest station. Positive correlations were found between the cumacean distribution and the organic content and percentage of coarse sand of the sediments. Predominance of Nannastacidae in front of other cumaceans could be explained by their type of feeding (i.e. predators or scavengers), which may be more successful in the deep seafloor of an oligotrophic sea such as studied herein. The presence in the deepest sampling sites of species shared with faunas of surrounding oceans suggests a link between these faunas and those of deep Antarctic waters.