Monographs Details: Stigonema hormoides var. rigidum 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 250-350 µ long, 8.5-10 µ diam., moderately curved, sparsely branched, firm and rigid; cells in youngest specimens cylindrical, quadrate to one-half the diameter long, later becoming dolioform to subspherical; tegument thin, close-fitting, firm, homogeneous, dark brown.

Distribution and Ecology - Growing on red earth near Mayagiiez, no. 880 f, type.