Monographs Details: Fissidens brachypus Mitt.
Authority: Pursell, Ronald A. 2007. Fissidentaceae. Fl. Neotrop. Monogr. 101 (Published by NYBG Press)
Synonyms:Conomitrium brachypus (Mitt.) A.Jaeger, Schistophyllum brachypodum Lindb., Fissidens townsendii Bizot
Description:Species Description - Plants dark green. Stems monomorphic, unbranched and branched, to 11 mm long x 1 mm wide; rhizoids basal, smooth, tan to reddish; axillary hyaline nodules present; epidermis and outer tier of cortical cells small, incrassate, pigmented; inner cortical cells larger, thin-walled, hyaline; central strand absent. Leaves ± crispate when dry, distant to loosely imbricate, as many as 25 pairs, oblanceolate to oblong, obtuse-rounded, to 1 mm long x 0.25 mm wide; margin crenulate-serrulate, limbate on proximal 1/2 of vaginant laminae of larger leaves, limbidial cells unistratose; costa ending 2-6 cells below leaf apex, bryoides type; dorsal lamina rounded at insertion; vaginant laminae of cauline leaves ± 1/2 leaf length, acute, equal to ± unequal; laminal cells distinct, eguttulate, unistratose, firm-walled, mammillose, irregularly hexagonal, 6-11 µm, sometimes larger, oblong, smooth in proximal halves of vaginant laminae. Monoicous (gonioautoicous); perigonia gemmiform, axillary; perichaetia terminal on stems and branches. Sporophytes 1 per perichaetium, yellow, darkening with age; seta smooth, to 1.2 mm long; theca exserted, erect, radially symmetric, to 0.45 mm long, stomatose, exothecial cells quadrate, collenchyma-tous; peristome scariosus type; operculum conic, short-rostrate, 0.25 mm long. Spores finely papillose, 12-18 µm diam. Calyptra cucullate, prorate, 0.25 mm long.

Discussion:This distinctive little moss grows exclusively on a freshwater sponge (Metania sp.), the narrowest substratum of any species of Fissidens known to me (Buck & Pursell, 1980). The species can be identified with certainty by recognizing this substratum. The species might be confused with another aquatic species, F. acacioides, which has an overall similar general aspect. However, F. acacioides is much larger and is restricted to streams in southern Brazil, northern Argentina, and Paraguay. More importantly, the limbate vaginant laminae and mammillose laminal cells of F. brachypus differ from the elimbate leaves and smooth laminal cells of F. acacioides.
Distribution:GuainĂ­a Colombia South America| Amazonas Venezuela South America| Amazonas Brazil South America| La Paz Bolivia South America|