Monographs Details: Porphyrosiphon notarisii var. major 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 22-28 µ diam.; trichomes 18-23 µ diam.; cells quadrate to one-third the diameter long;, aeruginous; sheath relatively thin, homogeneous and hyaline when young, finally becoming thicker, pink, and somewhat lamellose when older.

Distribution and Ecology - Growing on rocks in the vicinity of Coamo Springs, no. 6008, type, collected by Dr. N. L. Britton; on soil along the road to San Lorenzo, no. 523; on soil north of Sabana Grande, nos. 930, 931, and 935 a.