Monographs Details: Tolypothrix penicillata var. brevis 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 1-2 mm. long, intermixed with other filamentous algae, main filaments 18 p diam., branches smaller; trichomes 12-14 µ diam.; cells cylindrical to slightly doliof orm, quadrate to
3 times as long; sheath thin, hyaline; heterocysts up to 50 µ long, cylindrical.
Distribution and Ecology - Growing among other filamentous algae and water plants, not forming a definite stratum alone, in a water reservoir at Eio Piedras, no. 118, type, and nos. Ill, 115, and 119 a; along the shore of Laguna Tortuguero, no. 843.
Discussion:The variety b re vis differs from the species in having shorter filaments with the diameter averaging greater and with the cells and heterocysts longer. No. 115 has mature cells averaging 38 to 45 µ long in the older parts of the trichome.