Monographs Details: Hydrocoleum rufescens 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 containing 1-5 trichomes, mostly straight, or somewhat tortuous, smooth, unbranched, narrow, spindle-form, closed at the apices when young, later the ends dissolving and the trichomes extruding; trichomes nearly parallel, separated from each other for the most part, moderately constricted at the dissepiments, acuminate at the apices; cells homogeneous, pale to bright aeruginous; cross-walls very thin; apical cell blunt-conical, with a very small calyptra; sheath ample, hyaline when young, changing to pinkish red at maturity, homogeneous.

Distribution and Ecology - Growing on clay soil among other Myxophyceae, together forming a very thin, compact stratum, Experiment Station, Mayagüez, no. 972, type.

Discussion:The organism described here is one of many in the collection which hover around the generic borders. The filaments are small for the genus Hydrocoleum and lack the characteristic welldeveloped calyptra or thickened end wall of the typical species of that genus. Its colored sheath and small number of trichomes within a sheath do not well coincide with typical members of the genus Microcoleus. Its unbranched filaments combined with its colored sheath and prostrate habit do not unmistakably ally it with any of the Schizothrix group. The material is mature and most of the trichomes separated more or less into hormogonia, hence characteristic attenuated and capitate ends are very sparse.