Monographs Details: Scytonema magnum N.L.Gardner
Authority: Gardner, Nathaniel L. 1927. New Myxophyceae from Porto Rico. Mem. New York Bot. Gard. 7: 1-144. pl. 1-23.
Description:Species Description - Filaments 400-600 µ long, 24-32 µ diam., densely interwoven, forming a flocculent stratum 1-1.5 mm. thick; trichomes 15-22 µ diam.; cells cylindrical to dolioform, subquadrate in the meristematic region, up to twice as long as the diameter in the older parts, purplish gray, mostly homogeneous; cross-walls thin but distinct; heterocysts numerous, of the same size and shape as the cells, yellowish brown; sheath thick at first, hyaline and homogeneous, becoming yellowish brown and lamellose, the lamellae not divergent, surface smooth.
Distribution and Ecology - Growing on rocks in a brook about five kilometers north of Utuado, no. 1609, type; on rocks between Utuado and Adjuntas, no. 1661.
PLATE 16, FIGURE 31
The material in the above-mentioned collections is well advanced in age, and the branching is very sparse, but as far as observed, the branches are geminate.