COMPARISONS OF THE BIOLOGY OF THE INTERTIDAL SUBANTARCTIC LIMPETS NACELLA CONCINNA AND KERGUELENELLA LATERALIS

Two limpet species occur intertidally on subantarctic SouthGeorgia, the patellid Nacella concinna and the siphonarlid Kerguelenellalateralis. N. concinna is confined to the lower shore closeto LWS; K. lateralis occurs in middle shore pools, so theirdistributions do not overlap. N. concinna has a much narrowerthermal niche (–12.9°C to +15.6°C) than K. lateralis(–17.8°C to +31.8°C). Environmental data are presentedto show that the upper lethal temperature of N. concinna islow enough to prevent the limpet living higher on the shore.Both limpet species are slow-moving, but K. lateralis showsincreasing speed with rising temperature, peaking at 15–20°C.In contrast, N. concinna moves actively down to –1.9°C(when sea water freezes), but there is a steady decrease inspeed of locomotion above +2°C. Locomotion ceases at 14°Cin N. concinna (c.f. 30°C in K. lateralis). Both speciesexhibit very low tenacities, but in N. concinna tenacity decreaseswith increasing shell length. In K. lateralis there is no effectof temperature on tenacity. Both species show a positive allometricrelationship between foot area and shell length. N. concinnafeeds upon microbial films and microepiflora, but K. lateraliseats colonial diatoms and Enteromorpha bulbosa. Observationson shell middens of the kelp gull Larus dominicanus showed thatthe gulls did not eat K. lateralis, though they ate great quantitiesof the less accessible N. concinna. Gulls ate N. concinna assmall as 11 mm shell length (within the size range of K. lateralis).Experiments on gulls demonstrated an unwillingness to eat K.lateralis, probably because the siphonariid extrudes a viscidwhite mucus when the foot is touched. (Received 9 May 1996; accepted 8 July 1996)     

THE RATIO OF CALCAREOUS AND ORGANIC SHELL COMPONENTS OF FRESHWATER SPHAERIID CLAMS IN RELATION TO WATER HARDNESS AND TROPHIC CONDITIONS

Shells from 14 populations of sphaeriid clams including Sphaeriumstriatinum, S. simile, Pisidium walkeri, Musculim partumeiumand M. iransversum were analyzed for organic carbon (µgCmg^–1 shell), nitrogen (µg,N mg^–1 shell) andCaCO_s (%CaCO₃ of total clam dry weight). Habitat waters wereassessed for total hardness (expressed as ppm CaCo₃), ppm Ca,ppm Mg, conductivity (µmho) and suspended organic Carbon(µgCl^–1). For all populations, shell organic C andN are positively correlated and there is an inverse relationshipbetween the amounts of shell CaCO₃ and shell organic carbon.Trophic considerations give the best correlation with shelltype at the generic level of consideration since species ofMusculium are found at the opposite end of the trophic scale(eutrophic) from all other populations studied. For S. striatinum,the most extensively studied species, the amount of shell CaCO₃is inversely related to water hardness. The selection of shellsin the Sphaeriidae is discussed in relation to structural-functionalneeds and habitat conditions ¹ Present Address: Department of Biology, Syracuse University,Syracuse, New York 13210, U.S.A. ² Present Address: Department of Zoology, Miami University,Oxford, Ohio 45056, U.S.A. (Received 5 December 1978;     

THE MORPHOLOGY OF TOXOGLOSSAN GASTROPODS LACKING A RADULA, WITH A DESCRIPTION OF NEW SPECIES AND GENUS OF TURRIDAE

The morphology of some deep-sea Turridae lacking radulae wasstudied. The main features of their digestive system are theabsence of a radula sac, venom and salivary glands and the reductionor absence of a proboscis. A new genus Teretiopsis including3 new species and T. thaumastopsis (Dautzenberg and Fischer,1896) is described. On the basis of differences of the digestivesystem when compared with other turrids lacking radulae themonotypical subfamily Taraninae Casey, 1904 new status (typegenus Taranis Jeffreys, 1870) is considered. It is shown thatthe process of radula reduction has occurred independently indifferent phylogenetic lines of Toxoglossa—the subfamiliesDaphnellinae and Taraninae among Turridae and the family Terebridae. (Received 8 August 1988; accepted 20 December 1988)     

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)     

THE ANATOMY OF CYLINDROTIS QUADRASI FORM OKINAWA ISLAND, JAPAN AND THE SUBFAMILIAL POSITION OF THE GENUS CYLINDROTIS MOLLENDORFF, 1895 (ARCHAEOPULMONATA: ELLOBIIDAE)

Cylindrotis quadrasi Mollendorff, 1895, the type species ofthe ellobiid genus Cylindrotis, was collected from Okinawa Island,southwest Japan. This is the first record of C. quadrasi inJapan and the third in the world. The anatomical charactersof this species, i.e. shell, head-foot, pallial cavity, radula,stomach, reproductive system, and central nervous system, aredescribed in detail for the first time. The significance ofthese observations is discussed and the subfamilial positionof Cylindrotis is reconsidered. Cylindrotis was included inthe Pythiinae, the most primitive group of the Ellobiidae, basedon the conchological characters alone. However, the male andfemale tracts of the reproductive system are entirely separated,and other internal organs exhibit highly derived conditions.Accordingly, Cylindrotis is transferred from the Pythiinae tothe Ellobiinae. Among the genera of the latter subfamily, Cylindrotisseems to be allied to Blauneria Shuttleworth, 1854 and LcucophytiaWinckworth, 1949. (Received 1 February 1993; accepted 7 June 1993)     

THE BIOLOGY OF THE NORTHEASTERN PACIFIC TURRIDAE II. OENOPOTA

The habitat, diet, some reproductive and mortality factors forseveral shallow-water species of the boreal turrid genus Oenopotafrom the Puget Sound region were determined. All fed exclusivelyon tubicolous polychaetes. Oenopota fidicula was a dietary andhabitat generalise Oenopota elegans eats Schistocomus hiltoniand lives in areas of shell fragments. Oenopota excunata eatsTharyx multifilis and is a habitat generalist. Oenopota tabulataappears to be a dietary generalist, but lives only on or nearrocks. The widely-distributed species, O. levidensis, eats spionidpolychaetes, primarily Polydora species, or Owenia fusiformis,and is a habitat generalist. Feeding frequencies are low asare population densities; although O. levidensis sometimes exceeds15 animals m^–2. Crabs are major predators upon turridsin some areas, but mortality causes are generally obscure. Spawningwas observed in four species, but only O. elegans and O. levidensishad viable larvae. Development takes 13–15 weeks, 6–7weeks in a capsule and 6–7 weeks as planktonic veligers.There are no nurse eggs. Settling was not observed. ^*Present mailing address: Bamfield Marine Station Bamfield,B.C. VOR 1B0 CANADA (Received 30 May 1982;     

REPRODUCTIVE CYCLES OF CERASTODERMA GLAUCUM(BRUGUIERE) AND C. EDULE (L.) WITH SPECIAL REFERENCE TO THE EFFECTS OF THE 1981-82 SEVERE WINTER

Gonadal changes in two species of Cerastoderma occurring indiscrete populations in South Wales were monitored by stereologicalanalysis during the breeding seasons of 1981 and 1982. Fecundityand spawning efficiencies were determined quantitatively. Therelationship between reproductive activity and changes in meatcondition are discussed. Both species are opportunistic breeders. Their normal patternsof reproduction are similar, consisting of minimum activityin winter and peak activity during spring/early summer. Thetwo species were affected differently by the severe winter of1981–82—C. glau-cum exhibited a single, ‘epidemic’spawning and resumed gametogenesis after a 4-month resting period.C. edule adopted a ‘polycyclic’ pattern withouta resting period. Both of these unusual reproductive strategies,augmented by reduced predation resulted in heavy spatfalls. (Received 20 March 1985; revised 20 March 1985;     

BROODING AND NON-BROODING DACRYDIUM (BIVALVIA: MYTILIDAE): A REVIEW OF THE ATLANTIC SPECIES

The Atlantic species of the marine bivalve genus Dacrydium arereviewed, with particular emphasis on their hinge and protoconchcharacters. The basic groundplan of a Dacrydium comprises afunctional primary ligament, a paired series of primary teeth,and a posterior row of secondary teeth separated from the latterby a secondary ligament; this can be transformed into a singleseries either by loss of the secondary ligament and mergingprimary and secondary teeth, or by loss of secondary teeth andligament through paedomorphosis. Twelve species are recognized, of which eleven are illustrated.One abyssal species is not separable morphologically from theIndian Ocean D. speculum Poutiers, 1989 and is new to the Atlantic;four new species (D. wareni, D. dauvini, D. filiferum and D.balgimi) are described; a Caribbean form which is hardly distinctfrom the Eastern Pacific D. elegantu-lum Soot-Ryen, 1955, isdescribed as a new subspecies D. e. hendersoni. The larvae are brooded in D. hyalinum (Mon-terosato, 1875),D. viviparum Ockelmann, 1983 and D. balgimi. The brooding specieshave larger larvae (protoconch 210 to 315 µm long) thanthe non-brooding (protoconch 120 to 150 µm long), andreach a smaller adult size (1.4 to 3 mm instead of 4.5–5mm). A phylogenetic reconstruction is attempted using parsimonyanalysis of hinge and shell characters as well as the brooding/nonbrooding character. (Received 22 October 1996; accepted 28 November 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)     

A NEW GENUS AND SPECIES OF LYMNAEIDAE FROM THE LOWER FRANKLIN RIVER, SOUTH WESTERN TASMANIA, AUSTRALIA

The shell and anatomy of a new genus and species of Lymnaeidae,Kutikina hispida, are described from the Franklin River, S.W.Tasmania and the implications of this discovery, along withthe origins and relationships of the Australasian Lymnaeidae,are discussed. The new species lives attached to submerged limestonerock, has a very expanded shell aperture and, uniquely, theperiostracum bears short hairs. In addition there are apomorphicradular and anatomical characters separating this genus fromother lymnaeids. The new genus is compared with the other nativeAustralian Lymnaeidae. It is suggested that the taxonomy ofthe only other native Tasmanian species of Lymnaeidae, Austropepleatomentosa, a species widely distributed in temperate Australiaand in New Zealand, requires reexamination. Alternative hypothesesrelating to the zoogeography of the southern members of thefamily are discussed in relation to this taxon and the Recentgenus-group taxa of lymnaeids are listed in an Appendix andtheir differences from the new genus noted. (Received 20 June 1996; accepted 17 January 1997)     

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)     

LARVAL GROWTH AND THE INDUCTION OF METAMORPHOSIS OF A TROPICAL SPONGE-EATING NUDIBRANCH

The Hawaiian dorid nudibranch Hypselodoris infucata (Rppell& Leuckart, 1828) was reared to metamorphosis in the laboratory.Egg diameter averaged 88 µm and veligers hatched, afterabout 5 days at 25°C, with a coiled shell averaging 149µm in length. Larvae fed on phytoplankton grew to a maximumshell length of 306 µm in about 15 days. Larval growthwas affected by both quality and quantity of the algal diet.Some larvae were competent to metamorphose 16 days post-hatchingat 26°C, and competence could be retained for at least oneweek. Metamorphosis is complete within 24 hours of exposureto an inducer. At least three species of sponge, Halichondriacoerulea, Sig-modocia sp., and Tedania macrodactyla, in additionto the nudibranch's adult prey species, Dysidea sp., inducedmetamorphosis of competent larvae. Primary films grown on glassslides also induced metamorphosis in some larvae, as did 20µM excess potassium ions in seawater. These data suggestthat nonspecific induction of metamorphosis occurs in this specieseven though the adult nudibranchs are highly prey specific.This implies that in the field, H. infucata find Dysidea sp.after settlement and metamorphosis Present address: Dept of Genetics and Development, College ofPhysicians and Surgeons of Columbia Univeisity, 701 West 168thStreet, NewYork, 10032, USA (Received 22 June 1987; accepted 3 March 1988)     

Grazing of echinoderm larvae (Paracentrotus lividus and Arbacia lixula) on naturally occurring particulate matter

Larvae (72 hr old) of P. lividus and A. lixula grazed on varioussuspensions of natural particulate matter with a size rangeof 2 to 30 microns, and on two species of algae (Phaeodactylumtricor-nutum and Nitzschia sp.) — Larvae graze most in the size range where the particleconcentration is highest. — If larvae deplete certain size categories of particlesthey then graze other size ranges in which the concentrationis still high. — The grazing rate of the two species varied between 988and 91.949 µm³ per pluteus per hour. — For A. lixula larvae the grazing rate increases withincreasing temperature to a maximum at 22°C.     

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)     

ON THE STATUS OF THE GENERIC NAMES OF THE NUDIBRANCH GENERA CATRIONA, CRATENA, HERVIA, RIZZOLIA AND TRINCHESIA

The genus Catriona Winckworth (1941) is synonymous with TrinchesiaPruvot-Fol (1951) but not with Trinchesia von Jhering (1879). It has priority over Trinchesia Pruvot-Fol. The genus Cratena Bergh (1864) is valid and synonymous withRizzolia Trinchese (1877) but not with Hervia Bergh (1871). The genus Hervia Bergh (1871) is synonymous with Facelina Alderand Hancock (1855), but not all species of Hervia can be includedin the latter genus, and these should, therefore, be distributedamong other genera, some of which are listed. (Received 8 October 1954;     

INFLUENCE OF TEMPERATURE ON SURVIVAL AND GROWTH OF TWO FRESHWATER PLANORBID SPECIES, PLANORBARIUS CORNEUS (L.) AND PLANORBIS PLANORBIS (L.)

The survivorships and growth rates ofPlanorbarius corneus andPlanorbis planorbis were measured during the whole life spanof the snails at constant temperatures of 5, 10, 15, 20 and25°C. Life expectancy tables were constructed. The maximumlongevities for P. corneus (231 weeks) and P. planorbis (175weeks) occurred at 15°C and 10°C respectively. The extremetemperatures were particularly unfavourable. Snail growth which was expressed logarithmically was most sensitiveto temperature during the exponential stage. However, if weconsider a given species duringjts entire life span, there wereno significant differences between temperature groups whichwere in order of decreasing suitability: —P. corneus: 25, 20 and 15°C; 10°C; 5°C; —P.planorbis: 20 and 15°C; 25 and 10°C; 5°C. Using the growth constants from the Von Berta-lanffy's modeladjusted to give a gaussian curve, it was calculated that theoptimum temperatures for the growth of P. planorbis and P. corneuswere 19 and 20.5°C respectively. A mathematical model basedon spline functions makes it possible to predict the growthof snails over a wide range of temperatures. (Received 2 June 1993; accepted 18 November 1993)     

INTRASPECIFIC AND INTERSPECIFIC VARIATION IN SHELL MORPHOLOGY OF BIOMPHALARIA PFEIFFERI (KRAUSS, 1848) AND HELISOMA DURYI (WETHERBY, 1879) FROM MOSHI, TANZANIA, ANALYSED BY MORPHOMETRIC STUDIES

Helisoma duryi, a planorbid snail species, which is a potentialbiological control agent of the intermediate hosts of schistosomiasis,was introduced in an irrigation scheme (T.P.C.) in northernTanzania in 1972. The species has been present at T.P.C. since,and during a snail survey in January 1981, a great variationin the shell morphology of H. duryi, ranging from typical H.duryi forms to forms resembling Biomphalaria pfeifferi, theintermediate host of Schistosoma mansoni in the area, was observed.The Biomphalaria- Wkc forms of H. duryi could constitute anentire population but also occasionally occurred in populationsof typical H. duryi. This study was undertaken to determine whether simple shellmeasurements, or ratios between some of these could be usefulin discriminating between H. duryi and B. pfeifferi. Followingparameters were considered: shell height, shell diameter, diameterof the umbilicus, ratio between shell height and diameter ofthe umbilicus, and the number of whorls. (Received 29 July 1983;     

GROWTH, MORTALITY, AND FEEDING RATES OF THE SNAIL HELIX ASPERSA AT DIFFERENT POPULATION DENSITIES IN THE LABORATORY, AND THE DEPRESSION OF ACTIVITY OF HELICID SNAILS BY OTHER INDIVIDUALS, OR THEIR MUCUS

When reared at high densities, young Helix aspersa show lessshell growth, even if waste products are removed. They alsofeed less, and show increased mortality. It is suggested thatthese effects are linked to reduced activity. Juveniles showreduced activity in the presence of adults or their mucus. Mucusof adult Cepaca nemoralis also depresses the activity of bothadult and young Helix and Cepaea. ^* Present Address: Unit Zoologi, Universiti Kebangsaan Malaysia,Jalan Pantai Baru, Kuala Lumpur, West Malaysia. (Received 12 May 1981;     

Resource assessment in hermit crabs: the worth of their own shell

Animals gather information about the quality of a resource throughits assessment and behave accordingly as a result of adaptivemotivational changes. In the hermit crab Pagurus longicarpus,we investigated whether an individual was affected in its motivationto acquire a new shell by the quality of the domicile shell(own resource value [ORV]), of the offered shell (external resourcevalue [ERV]), or of both and asked whether its motivation wasaltered by the information gathered during shell investigation.We analyzed the behavior of hermit crabs inhabiting shells ofdiffering qualities and compared their willingness to acquirean offered shell—optimal, smaller than optimal, or largerthan optimal—by measuring the latency to approach it,the number of shell investigation, and its total duration. Crabsin smaller shells (SSs) approached more quick and often theoffered shell, whereas crabs in larger shells investigated theoffered shell more thoroughly. The readiness of crabs to approachthe offered shell and the extent of its investigation were independentof the ERV but were exclusively affected by the ORV, whereasthe number and duration of shell investigation did not changewith time as investigation proceeded, except for crabs in SSs.These results suggest that P. longicarpus' motivation to acquirea new shell is exclusively influenced by the value of the shellit inhabits rather than by the quality of the shell it is offeredand that this species does not gather—or does not use—informationabout ERV during investigation.