Monographs Details: Calothrix simulans N.L.Gardner
Authority: Gardner, Nathaniel L. 1927. New Myxophyceae from Porto Rico. Mem. New York Bot. Gard. 7: 1-144. pl. 1-23.
Family:Rivulariaceae
Description:Species Description - Filaments 7-9 µ diam., cylindrical except for a short distance in the apical portion, prostrate at the base, curving away from the host and becoming free, 200-250 µ (up to 400 µ) long; trichomes 6-7 µ diam., cylindrical, except at the outer end where it suddenly tapers into a short hair about 2 µ diam., constricted slightly at the dissepiments; cells quadrate to one-third as long as the diameter, aeruginous, densely congested with small irregular granules; heterocysts basal, single, spherical to subspherical, 6.8-7.2 µ diam.; sheath very thin, firm, hyaline, close-fitting and uniform throughout; spores 1-3-seriate at the base just above the heterocyst, cylindrical, 8-9.5 µ diam., 12-16 µ long.

Distribution and Ecology - Growing in water west of the Experiment Station, Rio Piedras, no. 1946, type.

Discussion:

PLATE 13, FIGURE 23

This species of Calothrix described above is similar in the cylindrical character to C. evanescens and to C. linearis of this paper, and especially in the possession of spores, the only species in the Porto Rican collection having this character. The plants are epiphytic upon a large species of Oedogonium. After the hairs disintegrate, the specimens resemble very closely members of the genus Microchaete.