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;     

AN ANALYSIS OF SHELL SHAPE VARIATION IN THE PAINTED TOPSHELL CALLIOSTOMA ZIZYPHINUM (L.) (PROSOBRANCHIA: TROCHIDAE

Littoral and sublittoral Calliostoma zizyphinum (L.) from fourteensites around Ireland are compared by a new method of shell shapeanalysis. The apparatus used is described and results show clearvariation between populations. It is also used to show similaritybetween the variegated and white morphs found in StrangfordLough. Patterns of growth are shown to be largely in responseto the habitat conditions encountered at each site. The meanapical angle of each population is shown to be of great importancein distinguishing populations of topshells, as it varies withthe relative exposure of each site. (Received 30 July 1986;     

MORPHOLOGICAL VARIATION IN THE PAINTED TOPSHELL, CALL1OSTOMA ZIZYPHINUM (L.) (PROSOBRANCHIA: TROCHIDAE), FROM INTER-TIDAL RAPIDS ON THE IRISH COAST

Shell shape variation in Calliostoma zizyphinum (L.) is examinedwith different techniques of analysis (profile, discriminant,canonical variate and ratio analysis). Shells are collectedfrom five tidal rapids systems, all in very sheltered inlets,where C. zizyphinum is to be found at shore levels higher thanthe normal shore distribution of LWNT to the sublittoral. Shellmorphology varies consistently with the local habitat conditions,such as water flow rate, relative exposure and shore level.populations can be distinguished using various shell parametersand shell profiles. Shells from two different levels in thesame rapids show the effects of their subtly different habitats. (Received 5 February 1987;     

INTRA-POPULATION VARIATION OF THE SHELL OF LITTORINA RUDIS (MATON) (MOLLUSCA: PROSOBRANCHIA)

Shell variation within a single population of Litlorina rudis(Maton), collected near the Biological Station at Trondheim,Norway, was studied. The variation of the shell features studied, which includedthe shape of the basal part of the outer lip, and the relativeheight of the spire, width of the shell and of the aperture,were found to be at least partially related to shell height.Furthermore, the shell shape in the population investigated,besides varying with age, also varies due to shell damage. Nosignificant differences were found between the shapes of theshells of males and females. The shell characteristics of different populations of L. rudisalso vary greatly, one of the causes being differences in theenvironmental conditions. When studying this variation betweendifferent populations, however, it must be emphasized that onlyundamaged shells of individuals of about the same age shouldbe compared, in order to obviate the effects of the variabilitydue to age differences and shell damage within each individualpopulation. ^*Contribution from Trondhjem Biological Station no. 199 (Received 18 February 1980;     

中国小蛹螺属一新种记述(前鳃亚纲,蛹螺科)

在整理广西陆生贝类标本中得小蛹螺属1新种,即具槽小蛹螺Pupinella(Pupinopsis)sulcatus sp.nov.,对新种进行了详细描述,并与近似种进行了比较。     

EVIDENCE FOR PREDATION AS A FACTOR IN DETERMINING SHELL COLOR FREQUENCIES IN A MANGROVE SNAIL LITTORINA SP. (PROSOBRANCHIA: LITTORINIDAE)

It was hypothesized that in Littorina populations living on Avicennia marina in Moreton Bay, Queensland, yellow shelled individuals are at a selective advantage over other shell colors and that this advantage is due to differential selection by predators. Yellow shelled individuals were more likely to be recaptured than others, indicating a higher survival rate of yellows. When predation was restricted on ten mangrove trees, the apparent advantage of yellow shells was removed. After 18 months, the relative frequency of yellow shelled individuals was significantly lower on experimental trees than on control trees. A combination of selection for crypsis and for the less common morph is suggested as the mechanism maintaining the high levels of variation in this species.     

CONTRIBUTION OF GENETIC AND ENVIRONMENTAL FACTORS TO SHELL SHAPE VARIATION IN THE LOTIC SNAIL SEMISULCOSPIRA REINIANA (PROSOBRANCHIA: PLEUROCERIDAE)

The genetic and environmental factors affecting shell shapein the freshwater snail Semisulcospira reiniana at Takahashiin Kyoto, central Japan, were studied by means of a rearingexperiment and field observations. Shell shape was characterizedby three parameters; W (whorl expansion rate), T (whorl translationrate), and S (roundness of generating curve). Estimated heritabilitieswere low in all three parameters and the largest component ofthe great shell variation in the Takahashi population was environmentalvariance, suggesting that the main source of shell variationwas phenotypic modulation, in response to the external environment.In the field, snails that were active in fast currents had largerW and smaller T, that is, a larger body whorl and a lower spire,than snails in slow currents. Substratum conditions relatedto T in resting periods although its cause was unclear. Mechanismsare suggested which in the absence of selection of genetic variationcould cause and maintain shell variation in S. reiniana in differentmicrohabitats. (Received 8 March 1996; accepted 3 November 1997)     

贵州环口螺科一新种(前鳃亚纲:中腹足目:环口螺科)

1998年7-8月作者在贵州南部地区考察,获得陆生贝类标本一批,经鉴定发现1新种,即茂兰腹皱螺Gastroptychia maolanensis sp.nov。隶属于前鳃亚纲,中腹足目,环口螺科,腹皱螺属。描述了新种形态特征,栖息环境,并对其近似种进行了讨论。     

中国裂唇螺属一新种记述(前鳃亚纲,中腹足目,蛹螺科)

笔者在整理福建龙岩地区陆生贝类标本时,经比对鉴定发现1新种,龙岩裂唇螺Schistoloma longyanensis sp.nov..隶属前鳃亚纲、中腹足目、蛹螺科、裂唇螺属.对新种形态特征、栖息环境作了记述,并与近似种进行了比较讨论.     

甘肃陆生贝类二新种(前鳃亚纲:中腹足目:环口螺科)

1998年4－5月作者在甘肃省南部地区考察,获得陆生贝类标本一批,经鉴定发现2新种,即大河腹皱螺Gastroptychia dahensis sp.nov。和清河倍唇螺Diplommatina qinghensis sp.nov.,隶属于前鳃亚纲,中腹足目,环口螺科,腹皱螺属,倍唇螺属。文中对新种形态特征,栖息环境进行了记述,并与近似种作了比较。     

PHYSIOLOGIC RACES OF PHYTOPHTHORA INFESTANS (MONT.) DE BARY IN NORTHERN IRELAND*

By using the detached-leaf technique and Black's series of differential host varieties, seven physiologic races of Phytophthora infestans (Mont.) de Bary have been distinguished as occurring in Northern Ireland. Six were found at the Dunanney potato variety trial plots, namely: race 1; race 2; race 4; race I, 2; race 1,4; and race I, z, 4. The remaining race, race 0, was isolated from the commercial potato crop.
In a survey, comprising seventy-three isolates, of the physiologic races occurring in the commercial potato crop, only race o and race 4 were found (3 and 70 isolates respectively).
Certain modifications to the detached-leaf technique have given improved results, including the formation of normal lesions and the elimination of atypical infections showing sparse sporulation.
The variation in the host-parasite reaction of the detached leaves and the identity of the common race in commercial potato crops are discussed.     

中国环口螺科二新种*(前鳃亚纲:中腹足目:环口螺科)

１９９７年８月作者在贵州南部地区考察,获得陆生贝类标本一批,经鉴定发现两新种,即荔波倍唇螺Ｄｉｐｌｏｍｍａｔｉｎａｌｉｂｏｅｎｓｉｓｓｐ．ｎｏｖ和小七孔倍唇螺Ｄｉｐｌｏｍｍａｔｉｎａｘｉａｏｑｉｋｏｎｇｅｎｓｉｓ．ｓｐ．ｎｏｖ,隶属于前鳃亚纲,中腹足目,环口螺科,倍唇螺属。对新种形态特征,栖息环境进行了记述,并对其近似种也进行了讨论。     

贵州环口螺科一新种记述(前鳃亚纲,中腹足目,环口螺科)

在整理贵州省贵阳地区陆生贝类标本时,经鉴定发现1新种,即奇异阿勇螺Arinia mirifica sp.nov..隶属于前鳃亚纲、中腹足目、环口螺科、阿勇螺属.对新种形态特征、栖息环境进行了记述,并对其近似种也进行了讨 论.     

织纹螺科一新种记述(腹足纲,前鳃亚纲,新腹足目)

在整理浙江沿海织纹螺科标本时,经传统方法和分子生物学方法鉴定发现1新种,即拟半褶织纹螺Nassarius (Zeuxis) semiplicatoides sp.nov..隶属于腹足纲、新腹足目、织纹螺科、织纹螺属、Zeuxis亚属.文中对新种的形态特征和栖息环境进行了记述,并与近似种进行了比较讨论.