Monographs Details: Scytonema pulchellum N.L.Gardner
Authority: Gardner, Nathaniel L. 1927. New Myxophyceae from Porto Rico. Mem. New York Bot. Gard. 7: 1-144. pl. 1-23.
Family:Scytonemataceae
Description:Species Description - Filaments 10-15 µ diam., moderately straight, long, arcuate, rigid, entangled into a flocculent stratum about 2 mm. thick, sparsely branched, either single under the heterocysts or geminate between the heterocysts; trichomes very distinct, variable in diam., largest in the meristematic regions, diminishing in the older parts; 5-10 µ diam., not constricted at the dissepiments; cells cylindrical, 2-3.5 times as long as the diameter in older parts of the trichomc, quadrate to one-half as long at the apices; pale olive-green, homogeneous or with one to several refringent granules; cross-walls distinct, thin; heterocysts of the same shape and size as the cells; sheath at first homogeneous and hyaline, becoming lamellose and various shades of brown when older, smooth, firm.

Distribution and Ecology - Growing on rocks by a stream, Utuado, no. 1574, type; on rocks, near Utuado, no. 1494, collected by Elizabeth G. Britton; on earth, Utuado, no. 1501 a; among moss, etc., three kilometers north of Utuado, no. 1605

Discussion:

PLATE 16, FIGURE 33

Scytonema pulchellum is apparently closely related to S. ocellatum Lyngb. but may be distinguished from it by the thick, smooth, lamellose sheath, resembling that of S. guyanense (Mont.) Born. & Flah., and by the long cylindrical cells in the older parts often containing refringent granules. The branches are about equally single or geminate, the single branches arising under the heterocysts.