Monographs Details: Phormidium interruptum var. capitatum 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 - Trichomes 6.5-7.4 n diam.; cells quadrate or longer; terminal cell rounded, capitate, otherwise as the species.

Distribution and Ecology - Growing in the vicinity of Humacao, no. 540, type.

Discussion:The variety capitatum differs from the species only in the characters mentioned in the diagnosis. The trichomes are larger; the cells longer, and the end cell, at maturity, has a thickened terminal wall.