Scytonema catenulum N.L.Gardner
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Authority
Gardner, Nathaniel L. 1927. New Myxophyceae from Porto Rico. Mem. New York Bot. Gard. 7: 1-144. pl. 1-23.
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Family
Scytonemataceae
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Scientific Name
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Description
Species Description - Filaments densely aggregated into erect fascicles 1.5-2 mm. long, more or less agglutinated by their gelatinous walls; 18-26 µ diam., sparsely branched; trichomes moniliform when old, 8-12 µ diam., the greater diameter being at the apices, diminishing gradually in the older parts, in some cases entirely vanishing, at the same time the sheath increasing in thickness correspondingly; cells compressed dolioform at the apices, becoming subspherical in the older parts, yellowish green to bright aeruginous, homogeneous; cross-wall inconspicuous; heterocysts compressed spherical to concave when old; sheath subgelatinous, homogeneous, and hyaline when young, becoming indistinctly lamellose and ocreate at the apices, and yellowish when mature, roughened on the surface; branching mostly single toward the apices, geminate in part below.
Distribution and Ecology - Growing on rocks about ten kilometers north of Utuado, no. 556, type, and on earth, no. 1561.
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Discussion
PLATE 17, FIGURE 34
This species of Scytonema is well marked by the character of the cells combined with the indistinctly ocreate sheath. The cells in the meristematic region are very short and dolioform. As the growing region moves forward, the successive cells become more and more spherical, the sheath thickening and pushing in between the cells and eventually, in many instances, completely separating them. As the successive cells diminish in diameter, the sheath becomes correspondingly thicker, and finally many cells completely disappear.