Antarctoscyphus fragilis Pena Cantero, Svoboda and Vervoort 1999
Antarctoscyphus fragilis Peña Cantero, Svoboda and Vervoort, 1999 (Figures 5 (e,f), 9) Antarctoscyphus fragilis Peña Cantero et al., 1999, p. 1748 –50, fig. 3. Material examined Eltanin: 21/282, one stem, 33 mm high, with only one paired branch left, and a highly fragmented stem (longest fragment c....
| Main Authors: | , , |
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| Format: | Other/Unknown Material |
| Language: | unknown |
| Published: |
2017
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| Subjects: | |
| Online Access: | https://zenodo.org/record/5191176 https://doi.org/10.5281/zenodo.5191176 |
| Summary: | Antarctoscyphus fragilis Peña Cantero, Svoboda and Vervoort, 1999 (Figures 5 (e,f), 9) Antarctoscyphus fragilis Peña Cantero et al., 1999, p. 1748 –50, fig. 3. Material examined Eltanin: 21/282, one stem, 33 mm high, with only one paired branch left, and a highly fragmented stem (longest fragment c. 53 mm long), on gravel. Diagnosis Erect stems, up to 140 mm in height. Largest stems basally polysiphonic. Stem internodes long, limited by slight perisarc constrictions, usually arranged in a marked zigzag. Cauline apophyses far below distal node, forming a large angle with stem. Paired branches divided into long internodes. Paired branches slightly branched. Each paired branch branching at second and seventh internodes, giving rise to secondary branches; first second-order branch usually branching at third internode, forming one tertiary branch that, occasionally, gives rise to one fourth-order branch. Hydrothecae widely separated, alternately arranged in two planes, with strong tendency to unilateral disposition. Hydrotheca cylindrical, slightly curved outwards. Adcauline wall completely free, convex basally, roughly straight distally, as it happens to abcauline wall. Hydrothecal aperture cusps of similar development and separated by shallow embayments. Gonothecae unknown. Description Stems basally polysiphonic, up to 140 mm high. Material much fragmented; the largest fragment, distally and basally broken, 53 mm long, and slightly polysiphonic, except for the most distal 14 mm. Diameter of stem c. 300 µm. Stems indistinctly divided into internodes, with slight perisarc constrictions. Stem internodes relatively long (c. 800 µm) and arranged in a marked zigzag (little marked in some stems). Cauline apophyses placed far below distal node, forming a large angle with stem. Paired branches divided into long and thin internodes, each with one hydrotheca (Figure 9 (a)). Paired branches slightly branched; sometimes unbranched (Figure 9 (a–c)). Branches up to fourth order present; each paired branch branching at its second ... |
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