Monographs Details: Hapalosiphon tenuis 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 - Creeping filaments very profusely branched unilaterally, giving rise to numerous, erect filaments producing a compact stratum; erect filaments slightly tapering upwards, 175-225 µ long, 6-7.8 µ diam. at the base, more or less branched near the base; trichomes 2.3-2.6 µ diam.; cells quadrate to 3.5 times as long as the diameter, homogeneous, blue-green, cylindrical to somewhat dolioform; sheath thin, firm, smooth, subgelatinous; heterocysts same shape and size as the cells, single or 2-3-seriate in the creeping filaments or in the lower part of the erect filaments.

Distribution and Ecology - Growing on serpentine rocks, forming a thin velvety stratum, north of Sabana Grande, no. 943, type; on bark, Utuado, no. 1496.

Discussion:PLATE 23, FIGURE 60