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| Registros recuperados: 44 | |
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| Hammen, L. van der. |
| Since 1964 I have been publishing a series of extensive descriptions and morphological studies of various groups of mites. Although this type of work is rather time-devouring, it enlarges our knowledge considerably as to structures hitherto generally neglected. At the same time, however, we must not lose our broader view on the Acarida as a whole: the analytical investigations should be supplemented by synthetic work. For this reason, I used to add to my descriptions a number of remarks on subjects of general importance. It now appears that this way of publishing does not keep pace with the development of my views. A number of stray observations and opinions did not come off, and had to wait a long time before being included in an appropriate study. For... |
| Tipo: Article / Letter to the editor |
Palavras-chave: 42.74. |
| Ano: 1968 |
URL: http://www.repository.naturalis.nl/record/318490 |
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| Hammen, L. van der. |
| A comparative study is made of the three groups (Cyphophthalmi, Laniatores and Palpatores) into which Opilionida are currently subdivided. Methods, principles and terminology, adopted in this paper, correspond with those of parts I and II of the present series of studies in Chelicerata. Special attention is paid to mouthparts and appendages, to opilionid relationships, and to the evolution of chelicerate characters. It is demonstrated that Cyphophthalmi present all the essential opilionid characters, and evidently do not constitute a separate group. It is also demonstrated that Opilionida are not closely related to Actinotrichid or Anactinotrichid mites, but to other groups with a so-called myliosoma (mouthparts associated with coxisternal feeding); these... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Opilionida; Chelicerata; Comparative morphology; Classification; Evolution; Phy- logeny.; 42.74. |
| Ano: 1985 |
URL: http://www.repository.naturalis.nl/record/317785 |
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| Hammen, L. van der. |
| In most groups of mites the gnathosoma is rather easy to study as a whole because it can be completely separated from the idiosoma without much difficulty. In Oribatid mites, however, the membrane attaching the chelicerae to infracapitulum and rostrophragma is very thin; separation of the gnathosoma consequently results in tearing the membrane, either between chelicerae and infracapitulum, or between chelicerae and rostrophragma. In both cases the original position of the chelicerae and their exact relation to camerostome and remaining part of gnathosoma, is difficult to reconstruct. As a result of this, only parts of the Oribatid gnathosoma have been described in literature. An extensive study of the infracapitulum (especially of its ventral surface) was... |
| Tipo: Article / Letter to the editor |
Palavras-chave: 42.74. |
| Ano: 1968 |
URL: http://www.repository.naturalis.nl/record/317700 |
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| Hammen, L. van der. |
| In the course of the last years, I have been investigating the morphology of various groups of mites. During this comparative study, special attention has been paid to the gnathosoma, which organ represents the specialized structure of the mouthparts in this subclass. Recently, while summarizing my results on the phylogeny of the gnathosoma (Van der Hammen, 1969), it appeared necessary to start from a more primitive Arachnid condition in which the chelicerae are still in front of the palps; at the same time, just as in the mites, the coxisternal region of the palp should be present, and the mouth should be in front of the chelicerae. This condition is indeed still found in one primitive order of Arachnidea, viz., the Palpigradida. Representatives of this... |
| Tipo: Article / Letter to the editor |
Palavras-chave: 42.74. |
| Ano: 1969 |
URL: http://www.repository.naturalis.nl/record/318742 |
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| Registros recuperados: 44 | |
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