SHELL SCARRING IN CALLIOSTOMA ZIZYPHINUM (PROSOBRANCHIA: TROCHIDAE) FROM STRANGFORD LOUGH, NORTHERN IRELAND

Pink and white shells of Calliostoma zizyphinum show both undamagedand damaged scars. White shelled individuals predominate inStrangford Lough, Northern Ireland where Calliostoma densitiesand scarring levels are high. No white shells were found intertidally,outside the entrance channel to the Lough. Significant differencesoccur in the size of Calliostoma shells between sampling sitesbut not between different colour morphs at each site. Howeverin pooled samples, pink individuals are significantly largerthan white individuals. When sites and morphs are consideredseparately, pink Calliostoma density is negatively correlatedwith water movement. At sites where pink Calliostoma occur,the percentage of pink shelled individuals is negatively correlatedwith total Calliostoma density. Damaged and undamaged scarring values per unit area of shell,show highly significant differences between sites and damagedscars are significantly higher in white individuals. Undamagedscars are not correlated with any of the environmental parametersrecorded, but are positively correlated with damaged scars suggestinga common causative factor. The level of damaged scarring ispositively correlated with crab/total Calliostoma ratio at allsites and where each colour morph was considered separately.Multiple regression analyses reveal that crab/Calliostoma ratiosaccount for 42% of the between site variation in damaged scars.Significantly higher levels of damaged scars are found at siteswith high crab densities and significantly larger individualsare found at sites where crab densities are intermediate invalue. The largest and most highly scarred individuals occur at siteswith most coarse substrata where Calliostoma are present intheir lowest densities. The higher scarring levels and smallersize of white individuals reflect either higher mortality orreduced growth in white shelled Calliostoma. (Received 25 November 1991; accepted 5 November 1992)     

The Effect of the Calyptra on the Plane of Guard Cell Mother Cell Division in Funaria and Physcomitrium Capsules

The calyptra influences the plane of division in guard cellmother cells of Funaria and Physcomitrium. Normally, capsulesexpand while sheathed by the calyptra and the axes of the stomataare parallel to the axis of the capsule in both genera. Removalof the calyptra from an elongating sporophyte leads to setathickening prior to capsule expansion and an essentially randomorientation of stomata. If the calyptra is removed from a sporophyteof Funaria at the time the division of the guard cell mothercells is expected, guard cells of abnormal shape and undividedguard cell mother cells are found in unusually high frequency.     

ALTITUDINAL VARIATION AND ADAPTIVE ZONES IN ARIANTA ARBUSTORUM: A NEW LOOK AT A WIDESPREAD SPECIES

Arianta arbustorum is a European land snail, occurring in bothlowland and mountainous regions. Its shell is usually globular,which makes the species aberrant among the Campylaeinae in shellshape, habitat, and wide, not exclusively montane range. Withincreasing altitudes, the shells usually decrease in size andbecome more conical. However, in some mountain stocks thereare populations with depressed shells, provided with an openumbilicus. This form (subspecies) is only known from formerPleistocene refugia. It is hypothesized that in the Pliocene, the primary montaneA. arbustorum, with a depressed shell, entered an additional,adaptive zone, while conquering damp lowland habitats. Thisresulted in an enormous range extension. In the new habitata different (globular) shell shape evolved and the species becamepolytypic. The subsequent glaciations wiped out most of theoriginal montane A. arbustorum with depressed shells. Wherethis had occurred, post-Pleistocene re-colonizing conspecificsnails with globular shells, found vacant territory and coulddevelop the dines mentioned before. The invading populationsdid not regain the original, montane, depressed shell shape.This shape was only retained in a few refugia, where the populationssurvived amidst the glaciers. (Received 9 February 1990; accepted 31 May 1990)     

SHELL STRENGTH OF COLOUR MORPHS OF THE MANGROVE SNAIL LITTORARIA PALLESCENS

The load required to break shells of the snail Littor-aria pallescens(Philippi) (Gastropoda: Littorinidae) has been established.Mass increases more than proportionally with size. Size forsize, relatively heavy shells are thicker than relatively lightones, and the thicker shells are stronger. Three samples fromdifferent localities differ significantly in strength. Littorariapallescens is polymorphic for shell colour. It is shown thatin two of the three samples, both from Papua New Guinea, individualsof the dark morph are significantly heavier and stronger thanthose of the yellow morph, while there is no difference betweenmorphs in the third sample, from Thailand. In the sample withthe most robust shells the dark individuals are stronger, massfor mass, than yellows. Thus, colour morph is sometimes, butnot always, associated with differences in shell characteristicswhich are likely to affect fitness. Where there is a difference,the dark morph is estimated to be on average about 22% strongerthan the yellow morph. The difference between morphs is smallcompared with the large variation in shell characters associatedwith size. (Received 20 May 1992; accepted 22 June 1992)     

An Experimental Investigation into the Response of Some New Zealand Sand Dune Species to Salt Spray

The tolerance to salt spray of 29 species, mainly from New Zealandsand dunes, was investigated. Plants were grown in water culturein a glasshouse and subjected to overhead salt spraying at intervals.Growth rates in many species were reduced by salt spray buta significant decrease occurred only in six native herbs. However,many species showed sensitivity in leaf necrosis. Tolerant speciesincluded Scirpoides nodosa, Elymus farctus and Desmoschoenusspiralis. Ammophila arenaria, tolerant of spray as an adult,was less so when younger. There was little correlation between tolerance to salt sprayand tolerance to root salinity. Some species were tolerant toboth, e.g. S. nodosa and E. farctus, and some intolerant toboth, e.g. Wahlenbergia congesta. One species, Lupinus arboreus,was glycophytic in respect to root salt but tolerant of aerialsalt. Other species, such as Senecio elegans L. and Austrofestucalittoralis, were intolerant of salt spray but tolerant of mediumroot salinities. For some species salt spray tolerance correlated well with fielddistribution, e.g. D. spiralis and Bromus diandrus. However,some species present in semi-fixed dunes close to the sea havemuch lower tolerance than would be expected from their fieldsituation, e.g. W. congesta. This apparent inconsistency couldbe explained by the ameliorating high rainfall on the West Coast,or protection by ridges. One environmental variable alone, suchas salt spray, could not explain the field distribution formany species. Salt spray, growth rate, live leaf area, New Zealand, dune species, root salinity     

Systematics and Ecology of Shell-Boring Polychaetes from New England

In a survey of shell-boring polychaeles of New England, representativesof five families were found: Spionidae, Cirratulidae, Capitellidae,Terebellidae, and Sabellidae. The five spionid species were studied extensively. These includePolydora commensalis Andrews, found only in shells occupiedby hermit crabs, P. concharum Verrill, P. socialis (Schmarda), P. websleri Hartman, and Boccardia hamata (Webster) , foundin various types of shell. Breeding periods were defined andthe larval development described for each species. Polydoraconcharum deposits egg capsules inwinter months, while the oilierpolydorids spawn in spring or summer. Morphology of planktoniclarvae is distinct in each species, although P. websteri larvaemay be confused with non-boring species such as P. ligni Webster.Polydora socialis adults are found in both shells and sedimentand have a unique grinding apparatus, a gizzard, between theesophagus and intestine. The cirratulid, Dodecaceria sp., follows an asexual mode ofreproduction. The syslematics of Dodecaceria is complex owingto multiple modes of reproduction. No sexually mature individualswere observed during the course of this study. Asexual budswerefound in the Fall. A sabellid, Pseudopolamilla reniformis (Miiller), is commonlyfound in theshells of Placopeclen magellanicits (Gmelin) inMaine waters. Its reproductionis unknown.     

SHELL COLOUR IN CALLIOSTOMA ZIZYPHINUM (L.) FROM STRANGFORD LOUGH, N. IRELAND

Shells of Calliostoma zizyphinum taken from Strangford Lough,N. Ireland are divisible into three distinct colour forms: white(=var lyonsi) intermediate (a pale variegated form) and purple(a dark variegated form). The predominance of white and paleshelled individuals within and the absence of white Calliostomaoutside the lough was confirmed. The proportions of animalswith white and variegated shells at selected sites were almostidentical with those previously documented, suggesting a temporalstability of colour form ratios. No differences in shell thicknessand pedal adhesion were demonstrated between these forms. Snails with white shells reflect radiant heat better, have lightercoloured feet, move more rapidly, show a greater incidence ofshell repair and are more frequently exposed on weed at lowtide, than those with either intermediate or purple shells.Increased proportions of white individuals may be associatedwith high population densities. Under such circumstances, itis suggested that increased mobility may, by increasing dispersion,reduce intraspecific competition. In the event of exposure atlow tide a white shell would help minimize thermal stress. (Received 9 February 1987;     

Borers in the Shell of the Sea Scallop, Placopecten magellnnicus

Shells of the sea scallop, Placopecten magellanictis Gmelinfrom Newfoundland waters were examined for borers by directstereomicroscopic and X-ray radio-graphic means. Young shells are first attacked by the boring sponge, Clionavastifica, and the spionid polychaetes, Polydora websteri andPolydora concharum. The former settles almost exclusively onthe lower valve, but as it grows it often spreads to the uppervalve via the hinge region. The spionids settle on the uppervalve or occasionally on the periphery of the lower valve. Older shells are bored by the cirratulid polychaete, Dodecaceriaconcharum, which usually settles in empty Polydora burrows andenlarges them as they grow. The bivalve, Hiatella arctica, settlesin Cliona holes. The burrows formed by the borers can be recognized on the radiographs.However, the identity of the present inhabitant cannot be predictedwith accuracy because the original borer is often replaced bynestlers. The rale of growth was documented by making sequential radiographsat monthly intervals from May to October 1968. Rate of growthin all forms appears to be temperature-dependent. The watertemperature increased from 1°C in May up to 18°C inAugust. Polydora concharum and P. websteri grew more rapidlyfrom July to October than in Mayand June, while Cliona and Dodecaceriaonly grew during the months of July to October.     

THE OPERCULA OF NERITOPSID GASTROPODS AND THEIR PHYLOGENETIC IMPORTANCE

The fossil record of neritopsid opercula and shells shows thatthe shell shape typical for Neritopsidae and Neritidae appearedin the Triassic. The ancestors of Neritimorpha were most probablyforms similar to Naticopsis. The operculum of Recent Neritopsisis composed of two calcitic parts secreted from inside and anaragonitic callus deposited from outside. Similar neritopsidopercula were already present in the Late Triassic. The firstopercula with asymmetrically situated muscle scars, possiblyancestral for neritids, also appeared at that time. (Received 27 May 2004; accepted 8 December 2004)     

THE SYSTEMATIC POSITION OF LAROCHEA FINLAY, 1927, AND INTRODUCTION OF A NEW GENUS AND TWO NEW SPECIES (GASTROPODA: SCISSURELLIDAE)

Species of the gastropod genus Larochea Finlay, 1927 are shownto be scissurellids without an anal shell slit or foramen. TheNew Zealand species, L. miranda Finlay, 1927 and L. secundaPowell, 1937, brood their young in the right subpallial cavityagainst a modified inner lip that is set well behind the aperturalplane. Larochea scitula n.sp. is based on shells from WanganellaBank, southern Norfolk Ridge. Larocheopsis n. gen. is introducedfor a minute species from off northern New Zealand that lacksa shell brood chamber. Larochea miranda and Larocheopsis amplexan.sp. are either gonochoristic with smaller males or consecutivehermaphrodites, while Larochea secunda and L. scitula are evidentlygonochoristic, having mature males and females of similar size. (Received 23 July 1992; accepted 10 December 1992)     

考考赖沟流域植被生产力模拟

 该文应用气象数据、土壤物理属性实测数据、土壤水分分布式动态模型和植被表面净辐射模型的模拟结果,利用多元线性回归分析方法,建立 了植被净第一性生产力模型,实现了鄂尔多斯高原东部砂质荒漠化地区考考赖沟流域尺度上30 m×30 m空间分辨率的植被生产力精确模拟,并 且用植被生产力的野外实测数据对模拟结果进行了验证表明: 实测值与模拟值在固定沙丘、半固定沙丘和样线2上都达到0.05显著性相关水平; 不同位置的实测植被生 产力数据多分布在1∶1直线附近,模拟值与实测值吻合较好;植被生产力实测值与模拟值的相对误差范围为3.22%～ 6.27%,偏斜度范围在-12.84%～4.43%。该文的研究方法可以为流域尺度上植被生产力的精确模拟提供借鉴和参考。     

Genetic Variation and Clonal Diversity of Psammochloa villosa(Poaceae) Detected by ISSR Markers

Genetic variation and clonal diversity of seven Psammochloavillosa(Poaceae) populations from northwest China were investigatedusing inter simple sequence repeat (ISSR) markers. Of the 84primers screened, 12 produced highly reproducible ISSR bands.Using these primers, 173 discernible DNA fragments were generatedwith 122 (70.5%) being polymorphic, indicating considerablegenetic variation at the species level. In contrast, there wererelatively low levels of polymorphism at the population levelwith the percentage of polymorphic bands (PPB) ranging from6.1 to 26.8. Analysis of molecular variance (AMOVA) showed thata large proportion of genetic variation (87.46%) resided amongpopulations, while only 12.54% resided among individuals withinpopulations. Clonal diversity was also high with 98 genets beingdetected from among 157 individuals using 12 ISSR primers. Theevenness of distribution of genotypes in P. villosa populationsvaried greatly, with all of the genotypes being local ones.No significant differences in genetic or clonal diversity werefound between populations in mobile or fixed dunes. The mainfactor responsible for the high level of differentiation amongpopulations and the low level of diversity within populationsis probably the clonal nature of this species, although selfingmay also affect the population genetic structure to some extent.The efficiency of ISSRs in identifying genetic individuals wasmuch higher than that of allozymes. An approximately asymptoticcorrelation was found between the number of genets detectedand the number of polymorphic loci used, suggesting that useof a high number of polymorphic bands is critical in genet identification.Copyright 2001 Annals of Botany Company Psammochloa villosa, ISSRs, genetic variation, clonal diversity     

An observation of episodic feeding and growth of larval Leiostomus xanthurus in the northern Gulf of Mexico

Four cruises were conducted in the northern Gulf of Mexico overtwo spawning seasons of the sciaenid fish Leiostomus xanthurus.On only one occasion did unusually high densities of larvaeand their principal microzooplanktonic foods co-occur. Peakdensities of larvae and microzooplankton were observed in athin lens of cool surface water that characterized a hydrographicdiscontinuity, and all larvae contained high numbers of foodorganisms in their guts. Instantaneous exponential growth ratesestimated from measurements of otolith growth increments, indicatedaccelerated growth on the day that larvae were collected. Alaboratory experiment verified that larval L. xanthurus respondsto an increased ration with accelerated growth that is detectableon otoliths. Together these data suggest that the spatial distributionof L. xanthurus larvae and their microzooplanktonic food ispatchy and that interactions of larvae and microzooplanktonmay be episodic.     

Self-incompatibility, Inbreeding Depression and Crossing Potential in Five BrazilianPleurothallis (Orchidaceae) Species

Intra- and interspecific experimental pollinations were madeto determine the mating systems and the interspecific crossingpotential in individuals from 24 populations of five Pleurothallisspecies. Pleurothallis johannensis, P. ochreata and P. teresshow weak or partial self-incompatibility while P. adamantinensisand P.fabiobarrosii are more strictly self-incompatible. Wefound no differences in fruit set between intra- and interpopulationintraspecific crosses, and there was no correlation betweenfruit set and genetic variability or inbreeding in these species.All species are interfertile and showed no correlation betweengenetic similarity and crossing potential. We scored fruitsfor seed viability and observed a strong inbreeding depressionin all populations; however, there was no difference in seedviability among intrapopulation, interpopulation intraspecificand interspecific cross-pollinations. These species are pollinatedby flies with a behavioural pattern that facilitates self-pollination.Self-incompatibility and inbreeding depression are apparentlyimportant in the maintenance of the unusually high levels ofgenetic variability found in these species. As generally observedin other orchid species, barriers to hybridization between thesePleurothallis species are at the level of pollination. Copyright2001 Annals of Botany Company Pleurothallis, Orchidaceae, mating system, self-incompatibility, inbreeding depression, fruit set, seed set, polyembryony, interspecific compatibility     

Boring of Shell by Caobangia in Freshwater Snails of Southeast Asia

Giard (1893) described Caobangia billeti, a freshwater sabellidpolychaete, based on material collected in what is now northernNorth Vietnam. Up to the present time it had not been re-collectedand Giard's observations that it is hermaphroditic, that itseggs undergo internal development, and that, rather than havinga posterior terminal anal opening, the anus opens far forward,have been questioned from time to time. Recently collected material, as well as older material in thecollections of the Division of Molluscs, Museum of Natural History,Smithsonian Institution, has allowed the confirmation ofGiard'sfindings and the observation of the burrows of Caobangia in22 species of molluscs from fast-moving streams in Ceylon, northernIndia, Assam, Burma, Thailand, Laos, Java, Sabah, and variousof the Philippine Islands. Burrowing in snail shells appears to take place subsequent tolarval metamorphosis as youngindividuals grow posteriorly froma capsule-like structure through the periostracum and into thecalcium carbonate of the snail shell. There appears to be nodifferentiated area of the worm which can be implicated as thesite of acidic secretions, and the setae of the worms seem notto be unusually worn, as would be the case if they were usedto wear away the shell material.     

Variation in shell morphology of Calliostoma zizyphinum (Gastropoda: Trochidae)

Differences in shell morphology in the intertidal prosobranchmollusc Calliostoma zizyphinum were studied from a number ofsites within four geographical regions of the British Isleswith varying exposures to wave action and crab predation. Meanvalues of damage scarring were highest in shells sampled fromStrangford Lough, Northern Ireland, and lowest in individualsfrom the Atlantic Coast. Shells collected from the Isle of Manwere smaller than those from either the Atlantic coast of Irelandor Strangford Lough. Shells from Strangford Lough had tallershells (higher aspect ratio) than shells from the County Downand Atlantic Coast and shells from the County Down coast weremore squat (lower aspect ratio) than those from all other areas.Shells from Strangford Lough were significantly thinner thanshells from all other geographical areas. The relationshipsbetween shell damage scarring and shell size and tallness werenot consistent among areas. Shells from Strangford Lough arenotable in showing a steep, positive relationship between shellsize and scarring and a steep, negative relationship betweenscarring and tallness. The unusual shell phenotypes observedin shells from Strangford Lough may be explained by rapid shellgrowth, which would not only allow Calliostoma to attain a sizerefuge from crab predators but also to recover successfullyfrom repeated crab attacks on the shell lip. Such a strategywould result in larger, thinner shells with a high number ofdamage scars. (Received 6 June 2006; accepted 20 December 2006)     

Rostromysis bacescuii gen. et sp. nov. and Megalopsis den-ticauda gen. et sp. nov. (Crustacea -- Mysidacea) from the south-west coast of Australia

Rostromysis bacescuii gen. et sp. nov. and Megalopsis denlicaudagen. et sp. nov. belonging to the tribe Leptomysini are describedfrom the south-west coast of Australia. The characters uniqueto the genus Rostromysis are the unusually long club-shapedrostrum and the large delicate lamella-like pleopods of thefemale, thus easily distinguishing it from the allied generaTenagomysis and Doxomysis. The genus Megalopsis is closely alliedto Leptomysis, Prionomysis and Promysis but is readily distinguishablein having a short linguiform uncleft telson with a pair of medianplumose setae.     

SPATIAL PATTERNS OF SHELL SHAPE OF THREE SPECIES OF CO-EXISTING LITTORINID SNAILS IN NEW SOUTH WALES, AUSTRALIA

The shape and relative weight of the shell have been shown tovary intraspecifically and interspecifically in a number ofspecies of gastropods, including many different littorinids.These differences give rise to different shell forms in differenthabitats. In those species which have non-planktotrophic development,differences in shell form among shores have been usually explainedin terms of natural selection because exposure to waves supposedlyfavours light shells with large apertures, while predation bycrabs on sheltered shores favours elongated, thick shells withsmaller apertures. Differences in shell shape among speciesfound at different heights on the shore have been explainedin terms of resistance to desiccation and temperature. Suchvariables would tend to act on a relatively broad-scale, i.e.causing differences among heights on a shore or among shores.Rates of growth, which might vary at much smaller scales withina shore, have also been shown to affect the shapes of many shells. In this study, the shape and relative weight of shells of threespecies of co-existing littorinids (Littorina unifasciata, Bembiciumnanum and Nodilittorina pyramidalis) were measured. These speciesall haveplanktotrophic development and they are found on manyshores where there is no evidence that they are preyed uponby crabs. Before explanations of shell shape are proposed, itis necessary that patterns of variation, within different partsof ashore and among different shores are clearly documented.These patterns were measured at a number of different spatialscales within and among replicate shores with different amountsof wave exposure. Large and small specimens were included toallow intraspecific comparisons among snails of different sizesfound at different heights on the shore. The results showedsignificant differences among shores in shape and relative weightof shells, but these differences could not be explained by exposureto waves. In addition, snails of different sizes and differentspecies did not show the same patterns although they were collectedfrom the same sites. Importantly, the shell shape of Liuorinaunifasciata varied significantly among sites at approximatelythe same height within a shore. These differences could notbe clearly correlated with density, mean size nor exposure towaves. The only consistent pattern was a decrease in relativeaperture size in specimens living higher on the shore. Modelsthat have commonly been proposed to explain shape and relativeweight of shells in other species of gastropods are not adequateto explain the small- and large-scale variation of the measurementsdescribed here. It is proposed that any selective advantageof shell morphology and the effects of any variables on thedevelopment of shell morphology in these species can only beidentified after appropriately designed and replicated fieldexperiments. (Received 4 March 1994; accepted 13 September 1994)     

SIZE AND SEX IN CYPRAEIDAE

Samples of Cypraea (Notocypraea) angustata Gmelin 1791 and ofCypraea errones L. 1758 have been measured, and the sex of theindividuals determined. The males of C. angustatawere foundto be significantly shorter than the females. Differences betweenother dimensions in this species, and between all dimensionsmeasured in C. errones, were of little significance It has recently been shown (Griffiths, 1961) that the malesof Umbilia hesitata Iredale were greater in length than thefemales. Other evidence in this paper, and some subsequent measurementsmade by Schilder and Schilder (1961) have suggested that theconverse might be true for some other species of CYPRAEIDAE Sample groups of shells of C. errones and C.(N) angustata havenow been measured. The shells were then cut open, and thesexof the animal determined by the presence or absence of a penis.The results are givenin Tables I and II (Received 10 March 1961;     

Sexual conflict over breeding substrate causes female expulsion and offspring loss in a cichlid fish

Females of the Lake Tanganyika cichlid Lamprologus callipterusexclusively breed in empty snail shells that males collect intheir territories. Male–male competition for shells issevere, leading to frequent shell stealing and territory takeover.As a consequence, males have breeding females in their shellsthat spawned with competitors. In this field study, we investigatedboth naturally occurring and experimentally induced encountersof territorial males with females that had spawned with othermales. We found that the breeding success of females that weretaken over by a different male was significantly reduced. Behavioralobservations after experimental shell relocation further showedthat males recognized females that they had not spawned with:males directed more exploration and manipulation behavior towardsuch shells compared with controls. Reoccupation rate of emptiedexperimental shells was significantly higher than that of unmanipulatedempty shells. This indicates that shell stealing and nest takeover,followed by female expulsion, contribute to the reproductivesuccess of L. callipterus males. We also found that female matechoice reduces expulsion risk: females preferred to mate withlarge males, and male size correlated with dominance. We concludethat the limited availability of breeding substrate is a keydeterminant of both intrasexual competition and intersexualconflict in this species.