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| Registros recuperados: 51 | |
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| Spoel, S. van der. |
| Biodiversity can be considered to be a human appreciation of the biological entity diversity. Diversity can be expressed numerically on the basis of taxa found, but it can also be expressed as the contribution of a specimen to the diversity, for which a formula is proposed. Diversity is the sum of the taxonomic or numerical diversity, and the ecological, genetical, historical, and phylogenetic diversity. Moreover, each group, or larger taxon, has its own characteristic diversity. These types of diversity are considered separately. One formula is tentatively proposed to calculate the overall diversity. Diversity in nature is variable, which is demonstrated in a diagram for comparison with societyinduced diversity changes. Diversity in the pelagic fluctuates... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Biodiversity; Diversity calculation; Ecology; Pelagic; Phylogeny. |
| Ano: 1994 |
URL: http://www.repository.naturalis.nl/record/504018 |
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| Spoel, S. van der. |
| A new form is described in the polytypic species Clio pyramidata LINNAEUS, 1767. This new forma excisa was found at 57°31'S 02°56'W and it is related to the forms convexa (BOAS, 1886) and sulcata (PFEFFER, 1879). The shape of the shell of the new form excisa shows a great resemblance to the shape of the shell of these two forms and also a resemblance is present to the shape of the shell of the form martensii (PFEFFER, 1880). This resemblance, however, may indicate a relationship as well as a parallel development. The new forma and the form martensii live in the same area, so that the chemo-physical characteristics of the water may have caused a parallel development. As indicated in a previous paper, the polytypic species Clio pyramidata consists of several... |
| Tipo: Article / Letter to the editor |
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| Ano: 1963 |
URL: http://www.repository.naturalis.nl/record/504828 |
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| Leyen, A. van; Spoel, S. van der. |
| Re-examination of the Diacria quadridentata species group based upon morphology of the shell and zoogeographic data, led to a new classification comprising the recent taxa: D. quadridentata, D. costata with an equatorial and a central water form, D. danae with an equatorial and a central water form, D. schmidti schmidti, D. erythra crassa and the fossil taxa D. schmidti cocidentalis and D. erythra erythra from surface sediments. A method has been developed to estimate the relative age of the population, based on the development of shell and soft parts. Shell growth in the period of minute and adult stages together does not exceed 0.2 mm, and differs from species to species. |
| Tipo: Article / Letter to the editor |
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| Ano: 1982 |
URL: http://www.repository.naturalis.nl/record/505420 |
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| Spoel, S. van der. |
| The mid North Atlantic between 24°N and 55°N along 30°W and between 20°W and 30°W along approx. 25°N, investigated by the AMNAPE cruises in the four seasons, spring (1980), summer (1983) autumn (1981) and winter (1982), is dominated by Temperate waters with a northern and southern branch of the North Atlantic Drift, Subtropical Sargasso Sea waters in the south and Subarctic waters in the north (Yen der Spoel, 1981, 1986; Van der Spoel & Meerding 1983; Pafort- van Iersel, 1985). The present study gives the relation of the microplankton distribution in the upper 5m of the water column with the hydrography and seasons. |
| Tipo: Article / Letter to the editor |
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| Ano: 1987 |
URL: http://www.repository.naturalis.nl/record/506328 |
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| Spoel, S. van der. |
| The columellar muscle system consists anteriorly of a high number of longitudinal branches surrounding a hydrocoel, which forms higher up two lateral, one ventral and four smaller dorsal bundles. These bundles enter the muscular envelope of head and nuchal region, which is formed out of the wing-wall muscles. The two lateral bundles proceed farest apically to insert on the buccal appendages; the four dorsal fibres fuse with the walls of buccal organs and oesophagus, while the ventral muscles run into the posterior and lateral footlobes. The wings are attached to the body by an extra right and left muscle neither derived from the columellar nor from the wing-wall muscle system. So the posterior and lateral footparts are mesopodal, the wings epipodal and the... |
| Tipo: Article / Letter to the editor |
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| Ano: 1982 |
URL: http://www.repository.naturalis.nl/record/505289 |
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| Bleeker, J.; Spoel, S. van der. |
| The polychaetous worms collected by the Siboga-Expedition (1899-1900) are listed with some annotations. A few specimens – identified by Augener and Pettibone but never published – are added, so that this list gives a complete survey of all Polychaeta collected by the mentioned expedition. The types of 269 nominal species present in the Institute of Taxonomic Zoology (Zoological Museum), Amsterdam are incorporated in this list, for some species lectotypes are desinated. |
| Tipo: Article / Letter to the editor |
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| Ano: 1992 |
URL: http://www.repository.naturalis.nl/record/505308 |
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| Spoel, S. van der. |
| The pelagic fauna of the Red Sea shows special variation induced by its isolated character (Van der Spoel, 1971). Clio pyramidata from the Red Sea is usually incorrectly referred to as the tropical forma lanceolata (Lesueur, 1813) or the typical forma pyramidata Linnaeus, 1767. Some large samples with C. pyramidata from the northern Red Sea made it possible to establish the correct identity of these populations. Though special variation, like described for Diacria and Cavolinia species (Van der Spoel, l.c.), is found for Red Sea populations of C. pyramidata, the populations are not separated as an endemic taxon as the specimens resemble closely Clio pyramidata forma convexa (Boas, 1886) (figs. 1-4). The anterior parts are almost identical to those of... |
| Tipo: Article / Letter to the editor |
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| Ano: 1973 |
URL: http://www.repository.naturalis.nl/record/505325 |
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| Spoel, S. van der. |
| The protoconch in Limacina helicoides, Peraclis moluccensis, Styliola subula, Cavolinia globulosa, C. gibbosa, C. inflexa and C. longirostris are described; finer structures of the shell in these species and Hyalocylis striata, Diacra quadridentata and Cavolinia tridentata are described. The occurrence of a distinct protoconch-I and -II in Cavoliniidae is discussed as well as the taxonomic value of the structure of the ventral ribs in the Cavoliniidae mentioned. |
| Tipo: Article / Letter to the editor |
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| Ano: 1976 |
URL: http://www.repository.naturalis.nl/record/505087 |
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| Spoel, S. van der. |
| Shell growth and size variation in populations of Diacria trispinosa Clio pyramidata, Cuvierina columnella, and Cavolinia gibbosa are studied. Attention is given to differences in the size variations of the four species caused by differences in their developmental biology. The reproductive cycle of Clio pyramidata forma lanceolata in the Bermuda Area is described and it is shown that there are more than one protandric hemaphrodite sexual cycles in one animal. The vertical migration of the four mentioned species is discussed. |
| Tipo: Article / Letter to the editor |
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| Ano: 1973 |
URL: http://www.repository.naturalis.nl/record/505038 |
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| Troost, D.G.; Spoel, S. van der. |
| In C. inflexa the mantle gland and its border show twenty-two bands. Differences in banding with C. longirostris are discussed. It appeared to be possible to discriminate the soft parts of juveniles in both species. Of special value for discrimination is the shape of the lateral appendages. The shells can be distinguished by the relative length of the caudal spine, which is longer in C. inflexa than in C. longirostris. Different developmental stages of C. longirostris are described and those of C. inflexa are added for comparison. While for the latter species the soft parts grow larger parallel with the increment of the shell, this is not the case in C. longirostris, due to the occurrence of minute stages and shedding of the caudal spine. The differences... |
| Tipo: Article / Letter to the editor |
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| Ano: 1972 |
URL: http://www.repository.naturalis.nl/record/505296 |
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| Spoel, S. van der. |
| The technical details and hydrographical data of the hauls with open nets and opening-and-closing nets, made during the Amsterdam Mid North Atlantic Plankton Expedition are given together with the general conditions during the sampling period April 11 – May 2, 1980. A temperature and salinity profile between 55° and 25°N to a depth of 2000 m are presented with ten XBT records. |
| Tipo: Article / Letter to the editor |
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| Ano: 1981 |
URL: http://www.repository.naturalis.nl/record/505292 |
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| Registros recuperados: 51 | |
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