Monographs Details: Fissidens amazonicus Pursell
Authority: Pursell, Ronald A. 2007. Fissidentaceae. Fl. Neotrop. Monogr. 101 (Published by NYBG Press)
Family:Fissidentaceae
Description:Species Description - Plants pale green. Stems monomorphic, infrequently branched, to 15 mm [1.5 cm] long x 4 mm wide; rhizoids basal and axillary, smooth, light tan; axillary hyaline nodules absent; epidermis and outer cortical cells large, thin-walled, epidermis bulging; inner cortical cells smaller, thin-walled; central strand present. Leaves crispate when dry, usually distant, as many as 22 pairs, lanceolate to ovate-lanceolate, acute to apiculate, to 2.7 mm long x 0.7 mm wide; margin entire, limbate on all laminae, limbidium weak, limbidial cells unistratose; costa ending below distal ends of vaginant laminae, reduced bryoides type; dorsal lamina narrowed proximally, ending at insertion; vaginant laminae ± 1/2 leaf length, acute, equal; laminal cells eguttulate, unistratose, smooth, thin-walled, broadly prosenchy-matous to linear-rhomboidal, 68-120 µm 28-29 µm wide, marginal cells narrower with slightly thicker walls. Perichaetia terminal. Perigonia, sporophytes, and calyptra not known.

Discussion:This species, which apparently is restricted to banks of tributaries to the Amazon River, is distinguished by its procumbent habit, shrunken leaves when dry, short costa that does not extend beyond the distal ends of the vaginant laminae, and broad prosenchymatous to linear-rhomboidal laminal cells. Fissidens amazonicus is most apt to be confused with F. scariosus which has narrower prosenchymatous laminal cells. Moreover, the plants of F. scariosus are usually upright and have lanceolate leaves in which the costa extends beyond the usually unequal vaginant laminae. Fissidens amazonicus differs little from the South African F. wageri Dixon in Wager, but until sporophytes are found on the former species there is no compelling reason to synonymize the names.
Distribution:Mazaruni-Potaro Guyana South America| Amazonas Colombia South America| Vaup├ęs Colombia South America| Amazonas Venezuela South America| Roraima Brazil South America|