Monographs Details: Phormidium calcicola 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 forming a thick, tough stratum, densely encrusted with calcium carbonate, tortuous and intricately intertwined, 7-8 µ diam.; trichomes 5.8-6.4 µ diam., not constricted; apices not attenuated; cells quadrate, varying to slightly longer or shorter, contents homogeneous, pale aeruginous; cross-walls thin; end walls distinctly thickened, apical cell blunt, rounded; sheath thin, homogeneous, hyaline.

Distribution and Ecology - Growing in a waterfall, between Arecibo and Utuado, no. 1460, type.

Discussion:The habit character of this species of Phormidium is very pronounced.