Monographs Details: Scytonema variabile 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 mostly straight or arcuate, more or less coalesced into erect fascicles about 2 mm. high, sparsely branched, both single and geminate types of branching being represented; main filaments 34-42 µ diam., branches smaller, all filaments very variable in diameter in different parts; trichomes very variable in diameter in different parts of the same filament, usually a little larger at the apices than in the main body of the filament, up to 25 µ diam.; cells cylindrical, slightly constricted at the dissepiments to decidedly dolioform, mostly quadrate or less, in part 2 times as long as the diameter, bright aeruginous, in part homogeneous, and in part congested with granules; heterocysts as variable in shape and size as the cells; sheath hyaline to yellowish brown; 6-12 µ thick, homogeneous or with a few divergent laminae, subocreate, subgelatinous.
Distribution and Ecology - Growing among moss on a waterpipe by a stream near Maricao, no. 1149 a, type, and no. 1153.
PLATE 15, FIGURE 30
This interesting species of Scijtonema belongs equally well in either section II, Myochrotes Born. & Flah., or section III, Petalonema Berk., as aranged by Forti.14 The sheath becomes relatively thick and remains homogeneous in some parts of some of the filaments. In others there are a few laminae and they turn outward, as in the group Myochrotes. In cases in which several successive periods of growth have followed each other in rapid succession at the apices, the ocreate condition characteristic of Petalonema appears. Rather unusual variability exists in all of the characters of the species. The same filament may be almost twice as thick in some parts as in others. The cells may be very short, one-fourth the diameter long in the main body of the trichome. They may be perfectly cylindrical or doliof orm in the older parts of the trichome.