Monographs Details: Fissidens cylindraceus Mitt.
Authority: Pursell, Ronald A. 2007. Fissidentaceae. Fl. Neotrop. Monogr. 101 (Published by NYBG Press)
Synonyms:Conomitrium cylindraceum (Mitt.) A.Jaeger
Description:Species Description - Plants dark green. Stems monomorphic, unbranched and branched, to 10 mm long x 1.5 m wide; rhizoids basal, smooth, reddish; axillary hyaline nodules absent; epidermis and outer 1-2 tiers of cortical cells small, incrassate, pigmented; inner cortical cells larger, thin-walled, hyaline; central strand present. Leaves crispate when dry, usually distant, as many as 24 pairs, ± oblong, acute to obtuse, to 1.5 mm long x 0.5 mm wide; margin sharply serrulate, limbate and entire on proximal 1/2 or less of perichaetial and subtending leaves, limbidial cells unistratose; costa ending 2-5 cells below apex, occasionally percurrent, bryoides type; dorsal lamina truncate or rounded at insertion, not decurrent; vaginant laminae of cauline leaves ± 1/2 leaf length, acute, ± unequal, minor lamina usually ending 3/4 or more the distance between costa and margin; laminal cells obscure, eguttulate, unistratose, firm-walled, pluripapillose, irregularly hexagonal, 68 pm long, in transverse section twice as deep as wide. Monoicous (cladautoicous); perigonia and perichaetia terminal on stems and branches. Sporophytes 1-2 per perichaetium, yellow, darkening with age; seta smooth, to 1.3 mm long; theca exserted, erect, radially symmetric, cylindric, to 1 mm long, stomatose, exothecial cells quadrate to oblong, collenchymatous; peristome teeth anomalous, erect both wet and dry, divided almost to base into two slender filaments, papillose proximally, filaments vertically ridged below, spirally thickened above; operculum conic, long-rostrate, 0.7 mm long. Spores finely papillose, 11-15 µm diam. Calyptra cucullate, smooth to ± scabrous, to 0.6 mm long.

Discussion:Fissidens cylindraceus is distinct from other pluripapillose species by virtue of its cylindric theca and peristome teeth that are divided to the base and erect whether wet or dry. Without the sporophyte one cannot with any degree of certainty recognize this species. The gametophyte alone would probably be placed in F. pallidinervis although the unequal vaginant laminae should preclude this assignation.
Distribution:Darién Panamá Central America| Magdalena Colombia South America| Ecuador South America|