Monographs Details: Scytonema punctatum 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 loosely entangled into a floccose stratum 2-A mm. thick, moderately tortuous, sparsely branched, 18-26 µ diam.; trichome bright aeruginous, not constricted at the dissepiments, 14-18 µ diam. throughout; cells cylindrical, one-half to one-third as long as the diameter at the apices, quadrate to twice as long in the older parts of the trichome, very finely and more or less densely granular; walls thin and white; heterocysts of the same shape and size as the cells, slightly yellowish; sheath hyaline or in extreme age yellowish, homogeneous, filled with very small refringent granules, 2-3.8 µ thick
Distribution and Ecology - Growing on rocks between Utuado and Adjuntas, no. 1658, type.
PLATE 16, FIGURE 32
The species above described may be distinguished from other known species by the relatively large diameter of the trichomes, not diminishing appreciably in the older parts, the bright aeruginous cylindrical cells which are usually very finely granular, and the hyaline, finely punctate sheath, especially so in the older filaments.