محفوظ في:
| المؤلفون الرئيسيون: | , , , |
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| التنسيق: | Recurso digital |
| اللغة: | |
| منشور في: |
Zenodo
2001
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| الموضوعات: | |
| الوصول للمادة أونلاين: | https://doi.org/10.5281/zenodo.10237797 |
| الوسوم: |
إضافة وسم
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جدول المحتويات:
- <p><b><i>Crambe</i> Vosmaer, 1880</b></p><p><i>Diagnosis.</i> Encrusting sponges characterized by having aster-like desmas (astroclones or sphaeroclones), along with a category of large choanosomal (tylo)styles, a category of small ectosomal subtylostyles, and one or two categories of anchorateunguiferate isochelae. Irregularly spiny microxeas occur in some species.</p><p><i>Remarks.</i> It has long been recognized that, for unknown reasons, most populations of <i>Crambe crambe</i> and some of <i>Crambe acuata</i> produce neither desmas nor isochelae (e.g. Boury-Esnault, 1971; Vacelet <i>et al</i>., 1976). This fact has largely complicated both species and genus diagnoses in <i>Crambe.</i> However, it was recently found that laboratory populations of <i>C. crambe</i> reared in seawater experimentally enriched with silicic acid produce up to four spicule types, desmas and isochelae included, that were otherwise missing in most natural populations (Maldonado <i>et al</i>., 1999). Therefore, it must be concluded that production of asteroid desmas and isochelae is a genetic trait shared by all individuals of all <i>Crambe</i> species. The skeletal reduction observed in many natural populations of <i>C. crambe</i> does not appear to have a genetic basis, but seems to be a phenotypic skeletal inhibition induced by limiting levels of silicic acid in sublittoral waters. Consequently, the presence <b>/</b> absence of desmas and isochelae must be used cautiously in the taxonomy of both <i>Crambe</i> and other crambeids.</p><p>The genus <i>Crambe</i> is here reported for the fi rst time from the Pacific Ocean. It is noteworthy that it has not been reported to date from the well-known Caribbean sponge fauna or in nearby zones of the Central Pacific, such as the Galapagos Islands, which have recently been surveyed (Desqueyroux-Faúndez and van Soest, 1997; authors, unpublished data). Nevertheless, the presence of the genus in the western Pacific stratigraphic sediments can be inferred from the fossil sphaeroclones found in Lower Tertiary strata of Oamaru (New Zealand). Such characteristic sphaeroclones, though formerly attributed to the genus <i>Vetulina</i> by Hinde and Holmes (1892), most likely belong to a fossil species of <i>Crambe</i> (Uriz and Maldonado, 1995), namely <i>Crambe oamaruensis</i> (Hinde and Holmes, 1892).</p>