Monographs Details: Scytonema tenellum 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 200-300 µ long, 12-16 µ diam., flexuous and densely intertwined, more or less erect, forming a thin, very dark stratum, profusely branched; trichomes cylindrical, not tapering, very slightly constricted at the dissepiments, 10-14 µ diam.; cells one-half to one-fourth as long as the diameter, homogeneous, pale aeruginous, cross-walls very thin but plainly visible; heterocysts numerous, golden yellow, of the same shape and size as the cells, or in part almost quadrate; sheath thin, smooth, homogeneous, dark brown, close fitting; branching geminate, perpendicular at first, soon gently curving.
Distribution and Ecology - Growing on lava rock north of Sabana Grande, no. 936 a, type.
PLATE 18, FIGURE 38
Scytonema javanicum (Kuetz.) Born. & Flah. has several characters linking it with S. tenellum. The latter is to be distinguished, however, by its very much shorter filaments, its much more profuse branching, and its shorter cells. The branches are much curved in various directions and frequently two to three orders remain intact instead of separating as is usually the case.