Monographs Details: Calothrix conica 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 only very slightly swollen at the base, branching very sparse, up to 125 µ long, but mostly 45-65 µ long, 6.8-7.5 µ diam. at the base, straight or in part more or less curved, almost equidiametric throughout the entire length; trichomes 4.8-5.6 µ diam., 1-3 cells slightly larger at the base, and 1-3 cells attenuated at the apices; apical cell conical; no indication of any hair cells; cells cylindrical below, decidedly dolioform above, quadrate below to slightly shorter above, aeruginous, homogeneous; heterocysts spherical to subspherical, single, basal, conspicuous; sheath hyaline, thin and close-fitting, ephemeral; hormogonia short.

Distribution and Ecology - Growing on trees in a ravine near Coamo Springs, no. 1895, type.

Discussion:

PLATE 13, FIGURE 18

Calothrix conica is apparently related to C. tenella of this paper and to C. epiphytica W. & G. S. West. It is to be distinguished by the conical apices, almost cylindrical trichomes, dolioform, almost moniliform cells in the upper part of the trichomes and by the delicate hyaline ephemeral sheath. There is no indication of hairs. They may appear, however, in the early stage of the development of trichomes.