MORPHOLOGY OF THE MATURE SPERMATOZOON OF PHYSA ACUTA (DRAPARNAUD, 1801) (GASTROPODA: PHYSIDAE)

The morphology of the spermatozoon of Physa acuta (Draparnaud,1801) was examined using TEM. It was found to be of the modified-type,sharing characteristic features of other basommatophoran species.However, differences were noted in some cases, for example,in P. acuta the nucleus was torpedo-shaped with two helicalkeels, the midpiece possessed a maximum of three glycogen helices,the end piece was long and tapered and the total length of thespermatozoon was 365 µm. No identical spermatozoa havebeen found in other basommatophoran gastropods studied so far.If spermatozoon morphology is unique for individual specieswithin the genus Physa, it may provide a useful taxonomic toolin helping to clarify the uncertainty that surrounds the systematicsof this genus. (Received 26 February 1990; accepted 28 June 1990)     

A COMPARATIVE STUDY OF THE MATURE SPERMATOZOA OF BULINUS AFRICANUS (KRAUSS, 1848) AND B. GLOBOSUS (MORELET, 1866) (GASTROPODA: PLANORBIDAE)

The morphology of the mature spermatozoa of the closely-relatedfreshwater pulmonates, Bulinus africanus and Bulinus globosus,was examined using scanning and transmission electron microscopy.A comparison showed no useful differences that could be usedto distinguish the species though they did differ in one respectfrom Bulinus tropicus, the only other bulinid for which spermmorphology is known. (Received 12 August 1996; accepted 6 December 1996)     

GENETIC AND MORPHOLOGICAL VARIATION OF POPULATIONS BELONGING TO THE BULINUS TRUNCATUS/TROPICUS COMPLEX (GASTROPODA; PLANORBIDAE) IN SOUTH WESTERN ZIMBABWE

Aquatic snails from south western Zimbabwe belonging to theBulinus trunscatus/tropicus complex vary widely in shell formsuggesting that more than one taxon could be present. This possibilitywas investigated by making observations on snail samples from13 populations from the Plumtree area, in respect of allozymevariation (5 polymorphic loci), shell morphology (9 variables),copulatory organ and chromosome number. Comparative data wereobtained from snails from north western Zimbabwe identifieddefinitely as B. tropicus. Analysis of the genetic structurerevealed a high degree of polymorphism (P) ranging from 0.29–0.80among populations from Plumtree and expected heterozygosity(H_e) from 0.02–0.22. No enzymatic diagnostic loci werefound which could differentiate the different morphs or populationsand discriminant function analysis on the morphological datashowed an overlap of morphs among populations. Snails analyzedfor chromosome number were all diploid (2n = 36). Snails exposedto Schistosoma haematobium mira-cidia were all refractory. Thisinformation supports the view of a single species, B. tropicus,which is differentiated due to migration barriers and whereenvironmental variables might be implicated in the morphometricdivergence. (Received 31 July 1995; accepted 15 January 1998)     

LIFE HISTORY AND POPULATION DYNAMICS OF COCHLICELLA ACUTA (MuLLER) (GASTROPODA: HELICIDAE) IN A PASTURECEREAL ROTATION

The conical snail Cochlicella acuta was sampled over a 3-yearperiod in a pasture-cereal rotation and a nearby roadside wastelandat Hardwicke Bay, South Australia. The life cycle of C. acuta was primarily biennial in the agriculturalfields, with offspring being produced in large numbers in thepasture phase but not the cereal phase of the rotation. Thebreeding season lasted from autumn to spring. Snails were mostabundant in spring and summer, especially near the edges offields. During summer, snails aggregated on robust weeds suchas Reseda lutea. Many snails were killed by burning pasturesin autumn, prior to sowing crops. Snails were more abundantand smaller in size in the roadside wasteland than in the agriculturalfields. Strategies for the control of C. acuta in pasture-cereal rotationsare discussed. (Received 9 April 1990; accepted 10 August 1990)     

ALLOZYME COMPARISONS AND PLOIDY LEVELS AMONG SPECIES OF THE BULINUS TRUNCATUS/TROPICUS COMPLEX (GASTROPODA: PLANORBIDAE) IN CAMEROON

Allozyme electrophoresis, ploidy level, and, to a lesser extent,anatomy and shell morphology were used to characterize snailsof the Bulinus truncatus/tropicus complex in Cameroon. Starchgel electrophoresis revealed no intrapopulation variation within20 populations examined for 14 allozyme loci in 12 enzyme systems.Interpopulation differences in allozyme patterns were used todivide the populations studied into five groups. Each groupis distinguished by a unique combination of zymograms for hydroxybutyratedehydrogenase and isocitrate dehydrogenase. Four of these groupsare tetraploids and are identified as B. truncatus. Populationsof the most commonly found B. truncatus group are generallyaphallic, are frequently associated with transmission of S.haematobium, and generally occur at altitudes below 800 m abovesea-level. Populations of B. truncatus belonging to the otherthree groups are usually euphallic, not associated with S. haematobiumtransmision, and generally occur at altitudes above 1000 m.These four groups may represent distinct biotypes of B. truncatus.Populations belonging to the fifth group are diploid, euphallic,not associated with S. haematobium transmission, and occur inhabitats above 1000 m. This is the first confirmed report ofdiploid B. truncatus/tropicus-complex snails from this regionof Africa. They are tentatively identified as B. natalensis,a species previously thought to be limited to East and SouthernAfrica. (Received 31 October 1988; accepted 20 February 1989)     

FRESHWATER SNAILS OF THE BULINUS TRUNCATUS/TROPICUS COMPLEX IN KENYA: TETRAPLOID SPECIES

Studies in recent years on chromosome number in freshwater snailsbelonging to the Bulinus truncatus/tropicus complex demonstratedthe occurrence in Kenya of one diploid species, B. tropicus,and 2 tetraploid species, B. truncatus and B. permembranaceus.Further observations are now described on the morphologies ofthe tetraploid species, and their distributions. Observations were made on B. truncatus from 26 localities (11newly reported) and B. permembranaceus from 26 localities (7newly reported), in respect of chromosome number, egg proteins,enzymes (5 systems), shell (10 variables measured), male genitalsystem (normal or aphallic) and radula (1st lateral tooth, sizeand mesocone shape). B. permembranaceus differs most clearly from B. truncatus inegg proteins, enzyme-loci and in lacking aphallic individuals.Mesocone shape is generally less angular in B. permembranaceus.The shell of B. permembranaceus grows larger, has the columellamore commonly concave and its spire is proportionally higherand more acute. To distinguish these tetraploid species fromthe partly sympatric B. tropicus, observations on chromosomenumber and biochemical characters are necessary. The tetraploids are allopatric, B. truncatus being found rarelyas high as 1900 m altitude, whereas B. permembranaceus occupiesthe altitude range 1940–2760 m. B. truncatus may be expandingits distribution in Kenya in man-made waterbodies, while B.permembranaceus possibly is restricted by adaptation to coolconditions and by interaction with B. tropicus. Differencesbetween B. truncatus and B. permembranaceus, both morphologicaland biochemical, indicate their origins lie in independent episodesof tetraploidy. ^*Member of External Scientific staff, Medical Research Council (Received 31 October 1988; accepted 6 December 1988)     

RESTRICTION ENZYME ANALYSIS OF DNA FROM SPECIES OF BULINUS (BASOMMATOPHORA: PLANORBIDAE) USING A CLONED RIBOSOMAL RNA GENE PROBE

A ribosomal RNA gene probe (pSM889) has been used to study restrictionenzyme digests of various species of Bulinus. In order to minimiseproblems of DNA shearing associated with snail tissues a methodof extracting nucleic acids from material embedded in agaroseblocks has been used. Restriction enzyme digests with Bgl IIand Bam HI hybridised to pSM889 showed clear differences betweenB. truncatus, B. wrighti, B. africanus and B. forskalii, representingthe four species groups of Bulinus. No differences were observedbetween samples of B. tropicus and B. truncatus digested withBam HI, Bgl II and Pst I. Intra-specific variation was observedbetween samples of B. forskalii from Säo Tomé andAngola digested with Bgl II and Hind III although restrictionprofiles for Bam HI, Pst I and Bst EII digests were similar.Intra-specific variation was also observed between two differentpopulation samples of B. wrighti from South Yemen using BamHI and Bgl II digested genomic DNA hybridised to pSM889. (Received 5 December 1989; accepted 19 April 1990)     

Invasion of ancient Lake Titicaca by the globally invasive Physa acuta (Gastropoda: Pulmonata: Hygrophila)

A vital population of Physa acuta, a globally invasive species of freshwater gastropods was dicovered in ancient Lake Titicaca in April 2007. The population was found near Chucuito (Bahia de Puno) on the Peruvian side in close proximity to a boat landing of the aquaculture facility of the University of Puno. Physids occured in great abundances at this site on macrophytes in depths from 0 to 2 m. Physa acuta was associated with members of the Heleobia andicola species complex as well as with Heleobia otorni, Biomphalaria andecola, and Uncancylus crequi. Species identity was confirmed by morphological and molecular methods. We discuss the mode of introduction and raise a cautionary note on the potential impact of this global invader on the endemic gastropod fauna of ancient Lake Titicaca.     

Autoecology and some life history stages of Dinophysis acuta Ehrenberg

A persistent and unusual bloom of Dinophysic acuta Ehrenbergin the RIas Bajas (Northwest Spain) from early July to mid-November1989, was associated with a diarshetic shellfish poisoning (DSP)outbreak that prevented mussel extraction in some areas fromearly August to mid-December. Integrated samples (0–5,5–10 and 10–15 m) were taken once or twice a weekat six stations. Maximum numbers of D.acuta (up to 2.3 10⁴intheintegratedsamples)andpercentageofobserveddMdingcells(upto3l%),appearedin August, and formed a maximum in the thermodine. Cellnumbers were minimal when upwelling caused a breakdown of stratification.Fligh numbers of D.acuta (up to 1.8 10⁴ cells 1^–1 appearedagain when persistent south winds in late October caused a reversalof the circulation. Thus, the two cell maxima occurred duringtwo distinct hydrographic regimes, but in both cases at temperaturesof 15–17C. Numerous cells with one typical D.acuta valve,but the other valve reduced in size, were seen during the bloom,as well as Dinophysts dens Pavillard cells that might be a lifecycle stage of D.acuta. Other observations include double- walled,unwinged forms that are perhaps some kind of cyst, and a hypothetical‘fertilizing tube’ emerging from the larger cellof a D.acuta/D.dens couplet. It is suggested that the maximaduring stratification and during downwelling episodes couldcorrespond to periods with a predominance of in situ growthand physical accumulation, respectively, and that the exceptionalmeteorological conditions during 1989 provided the optimum scenariofor the unusual occurrence of D.acuta.     

THE BIOLOGY AND FUNCTIONAL MORPHOLOGY OF MYTILOPSIS SALLEI (RECLUZ) (BIVALVIA: DREISSENACEA) FOULING VISAKHAPATNAM HARBOUR, ANDHRA PRADESH, INDIA

Mytilopsis sallei (Récluz) (Dreissenacea) has been introducedinto Visakhapatnam harbour, India. The normal distribution ofthe species is Central America and it is here contended thatthe species has been introduced into the Indo-Pacific via thePanama canal (opened in 1915) attached to the hulls of ships.M. allyneana (Hertlein & Hanna) with a distribution restrictedto Fiji is considered synonymous with M. sallei. The literature on M. sallei is reviewed and it is shown thatthe species has wide temperature, salinity and oxygen tolerancesand thus transport across a variety of water masses is entirelyfeasible. The species also possesses a fast rate of growth,a high fecundity and matures early. It is an opportunistic specieswhich free from the restraints that normally hold it in checkin its natural environment, poses a serious fouling threat toharbours throughout the Indo-Pacific and to the endemic fauna. The morphological adaptations of M. sallei are also describedand compared with those of Dreissena polymorpha (Pallas) inparticular and other fouling bivalves in general. The speciesis ideally adapted to life in turbid estuaries experiencingwide variations in temperature, salinity, oxygen and turbulence.A warning against further introductions is given. (Received 14 December 1979;     

中国特有的弯头果蝇种亚组及二新种记述(双翅目，果蝇科)

本文记述弯头果蝇种亚组的二新种,施氏果蝇 Drosophila (Drosophila) shi sp. nov.,短乳突果蝇Drosophila (Drosophila) brevipapilla sp.nov.,并对中国特有的弯头果蝇种亚组中11 个种的分布进行了分析。     

TEMPORAL VARIATION IN FORAGING BEHAVIOUR OF PATELLA GRANULARIS (PATELLOGASTROPODA) AND SIPHONARIA CONCINNA (BASOMMATOPHORA) ON A SOUTH AFRICAN SHORE

Foraging activity of two mid- to low- shore species of limpet,Patella granulans (Prosobranchia) and Siphonaria concinna (Pulmonata)from an exposed shore on the Eastern Cape coast of South Africawas monitored. In both species, activity was compared duringspring and neap tides and, in P. granularis between summer andwinter. Rhythms of activity of the two species were similar,with foraging excursions being mainly associated with nocturnallow tide times, although some P. granularis foraged during daytimelow tides. It is suggested that foraging excursions in P. granularisare triggered by wave action. Both species foraged further onspring tides than on neap tides and this is suggested to bea result of the limited time limpets have to forage. P. granulariswas also found to forage further during summer when comparedto winter and the possibility that seasonal micro-algal productivityinfluences foraging distances in limpets is discussed. The foraging activity of both species could be divided into3 distinct phases, a relatively rapid outward phase, a muchslower foraging phase and a rapid homeward phase. Whether ornot these limpets graze throughout an excursion is not known.S. concinna was found to home to a fixed scar, although duringthe experiment some scar-swapping occurred. P. granularis didnot home to a fixed scar but possessed a ‘home range’(approx. 5 cm²) to which it returned after each excursion. Patella granularis was found to move randomly during foraging,whilst S. concinna foraged in a non-random direction -whichtook individuals upshore. No tidal-influence is thought to bepresent in this case and the possibility of a learning componentin the foraging behaviour of certain limpet species in relationto the return to optimal feeding patches is discussed. (Received 18 May 1996; accepted 2 September 1996)     

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)     

Pollinator Specificity and Convergence in Fly-pollinated Pleurothallis(Orchidaceae) Species: A Multiple Population Approach

We studied the floral biology of 12 populations of five rupicolousPleurothallis(Orchidaceae) species occurring in campo rupestre vegetationat nine localities in Brazil. All of these species are pollinatedby flies belonging to the families Chloropidae and Phoridae.In the five Pleurothallis species studied, all conspecific populationsattracted the same pollinator species. All pollinators werefemales; they laid eggs in flowers of the two nectarless species,but never in the flowers of nectar-presenting species. The twopairs ofPleurothallis species with similar flower morphologiesand odours attracted the same pollinators: P. johannensis -P. fabiobarrosii, pollinated by Tricimba sp. (Chloropidae) andP. teres - P. ochreata pollinated by Megaselia spp. (Phoridae).There was no overlap in the distribution of thePleurothallisspecies that shared pollinators. Despite similarities in floralmorphology and odour, genetic data show that these species pairsare not each other's closest relatives. We hypothesize thatthese similarities are due to convergence in allopatric speciesthat evolved similar pollination mechanisms. Conversely, thereare reasons to believe that adaptation to different pollinationmechanisms occurred in the closely related species P. johannensisand P. teres.Copyright 2001 Annals of Botany Company Pleurothallis, Orchidaceae, floral biology, fly-pollination, Chloropidae, Phoridae, pollinator specificity, campo rupestre     

Salt Glands in Pappophorum (Poaceae)

Salt glands were observed in two species of Pappophorum, belongingto the tribe Pappophoreae (Chloridoideae, Poaceae). Glands resemblethose described in other genera of the Gramineae; they comprisetwo cells, a large basal one and smaller upper one. Gland densityper unit surface was much higher in P. philippianum, a facultativehalophyte, than in P. pappiferum, a glycophyte. The relevanceof the recretion process for the elimination of accumulatedNa in these two species is considered. The evolutionary significanceof the presence of glands in Pappophoreae and other membersof the Chloridoideae is discussed. Salt glands, Pappophorum philippianum, P. pappiferum, Poaceae     

PHYLLODESMIUM GUAMENSIS (NUDIBRANCHIA: AEOLIDOIDEA), A NEW SPECIES FROM GUAM(MICRONESIA)

A new species of Phyllodesmium (Aeolidoidea) from Guam (Micronesia)is described. Phyllodesmium guamensis n.sp. is characterizedby having two rows of denticles in the radular teeth, this beingdifferent from the previously described species of the genus.The shape of the teeth, however, is identical in all the speciesof the genus, and unique among aeolids. Furthermore, P. guamensispossesses a double row of cerata in the precardiac cluster andup to 10 post-cardiac ceratal rows. Also, P. guamensis showsa very dense accumulation of zooxanthellae in the ceratal digestivegland, which is ramified inside the cerata. This species feedson at least three species of the soft coral Sinularia: S. polydactyla,S. maxima and a third, undescribed species. The aeolid matchesthe colour of its prey and is cryptic on the soft coral surface. (Received 3 October 1996; accepted 28 April 1997)     

Molecular phylogenetic investigations of Bulinus (Gastropoda: Planorbidae) in Lake Malawi with comments on the topological incongruence between DNA loci

Freshwater snails of the genus Bulinus, subfamily Bulininae, are widespread in Africa and the Middle East. Several species are intermediate hosts for schistosomes, mammalian blood flukes that cause schistosomiasis. The genus is split into four species groups and without recourse to further molecular DNA studies, phylogenetic relationships within and between species‐groups remain obscure. For example, the Bulinus truncatus/tropicus species complex, which cannot be adequately defined with morphological characters, appears to be monophyletic but increased taxon sampling is warranted for confirmation when this group appears to contain species with limited sequence divergence in either mitochondrial 16S rRNA or Cytochome Oxidase subunit I (COI) loci. In the present study, taxonomic sampling is increased through addition of several taxa, including B. nyassanus and B. succinoides both endemic to Lake Malawi. From DNA analyses, these two species appear basal within the B. truncatus/tropicus species complex which provides an interesting evolutionary insight into its origins. The relationship of the B. truncatus/tropicus species complex with the three other groups, however, is more problematic as incongruence between loci and computational methodologies exist. This phenomenon is likely due to mutational saturation of the COI as evidenced by the transition : transversion ratio which also results in placement of the discoidal Indoplanorbis exustus, a member of the Bulininae, within the ingroup. To resolve these more basal incongruencies between species groups inspection of more evolutionary conserved molecular loci is needed, for example, the nuclear histone H3 gene, and 18S and 28S rDNA. Louise V. Gersdorff Jørgensen, Thomas K. Kristensen and Henry Madsen, The Mandahl‐Barth Research Centre for Biodiversity and Health, DBL — Centre for Health Research and Development, Department of Veterinary Pathobiology, Faculty of Life Sciences, University of Copenhagen, Jægersborg Allé 1D, DK‐2920 Charlottenlund, Denmark. E‐mails: lgj@life.ku.dk , tkk@life.ku.dk , hmad@life.ku.dk J. Russell Stothard, Biomedical Parasitology Division, Department of Zoology, Natural History Museum, Cromwell Road, London SW7 5BD, UK. E‐mail: R.Stothard@nhm.ac.uk     

Comparative paternal and infanticidal behavior of sympatric white-footed mice (Peromyscus leucopus noveboracensis) and deermice (P. maniculatus nubiterrae)

We studied parental and infanticidal behavior in the field andlaboratory in two ecologically equivalent and sympatric congeners,white-footed mice, Peromyscus leucopus noveboracensis, and deermice,P. maniculatus nubiterrae. Despite their close phylogeneticrelationship and ecological similarity, various aspects of parentaland nesting behavior of the two species were significantly different.P. maniculatus males were more paternal than were P. leucopusmales in that they retrieved pups, nested with pregnant femalesand females with newborn pups, and formed longer associationswith females than did P. leucopus males. Thus, P. m. nubiterraeexhibited more pair-bonding (monogamous) characteristics thandid either P. leucopus or P. m. bairdi, as reported in otherstudies. The behavioral differences may represent the differentevolutionary history of the three subspecies. Infanticidal behavior,however, was similar in both species. Dispersing and unmatedmales killed strange pups placed in experimental test chambersin the field, whereas mated males did not kill pups within theirown home ranges. Resident females of both species were moreinfanticidal than were males, killing pups in 90% of the trials.The results support the sexual selection and resource competitionhypotheses for male and female infanticide, respectively. [BehavEcol 1991; 2: 38-45]     

双尾蚜属的种类与地理分布

双尾蚜属Diuraphis Aizenberg全世界记录13种,主要分布在古北界和新北界。根据种类丰富度和特有种成分,欧亚大陆的欧洲和中亚为该属蚜虫的现代第一分布中心,北美为第二分布中心。本文提供了该属所有13个种的分种检索表。双尾蚜属蚜虫在中国共有7种,主要分布在蒙新区。它们是：麦双尾蚜Diuraphis noxia (Mordvilko), 害冰麦双尾蚜D. nociva Zhang et Liang,冰草麦蚜D. (Holcaphis) agropyronophaga Zhang, 披碱草蚜D. (Holcaphis) elymophila Zhang, 西方麦蚜D. (Holcaphis) frequens (Walker), 雀麦蚜D. (Holcaphis) bromicola Hille Ris Lambers和绒毛草蚜D. (Holcaphis) holci (Hille Ris Lambers)。对中国种类进行了简要描述。