Monographs Details: Calothrix juliana var. tenuior 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 700-900 µ long, 12-14 µ diam. at the base, tapering gradually to a hair at the apex; trichomes 9.5-11.5 µ diam. at the base; cells very short, 1.2-1.8 µ long.

Distribution and Ecology - Growing on the roots of water plants in Arroyo de los Corchos, no. 1696, type; on twigs in a stream, north of Maricao, no. 1291.