Monographs Details: Fissidens flabellatus Hornsch.
Authority: Pursell, Ronald A. 2007. Fissidentaceae. Fl. Neotrop. Monogr. 101 (Published by NYBG Press)
Synonyms:Fissidens pseudostipitatus Müll.Hal., Fissidens longifalcatus Müll.Hal.
Description:Species Description - Plants bright green. Stems monomorphic, 5-11 mm long x 2.0-3.5 mm wide, unbranched to profusely branched; rhizoids basal, smooth, reddish-brown; axillary hyaline nodules present; epidermis and 1-2 tiers of outer cortical cells small, incrassate, usually pigmented; inner cortical cells larger, thin-walled, hyaline; central strand present. Leaves mostly inrolled from tips, ± crispate when dry, imbricate, as many as 18 pairs, linear-lanceolate, obtuse, 2.0-3.4 mm long x 0.2-0.4 mm wide, perichaetial leaves longest; margin ± entire to crenulate, denticulate distally, elimbate; costa ending 7-25 cells below leaf apex, often spurred distally, oblongifolius type, distal part in transverse section showing 2 stereid bands separated by 6 (-7) enlarged cells arranged in 2 rows; dorsal lamina narrow, ending far above insertion or near insertion as a single file of cells; vaginant laminae of cauline leaves 1/2-2/3 leaf length, acute, ± equal, minor lamina ending near leaf margin; laminal cells distinct, eguttulate, unistratose, firm-walled, lenticularly thickened in dorsal and ventral laminae, irregularly rounded-hexagonal, 7-11 jmm long, plane or nearly so in vaginant laminae, juxtacostal cells in vaginant laminae larger, oblong, marginal cells smaller, mostly somewhat elongate and oriented obliquely. Monoicous (rhizautoicous) or dioicous (?); perigonia and perichaetia terminal on separate stems. Sporophytes 1 per perichaetium, yellow, darkening with age; seta smooth, 5-7 mm long; theca exserted, arcuate, bilaterally symmetric, 0.7-1.0 mm long, stomatose, exothecial cells quadrate to oblong, collenchymatous; peristome similiretis type; operculum conic, long-rostrate, 0.8-0.9 mm long. Spores smooth, 9-13 µm diam. Calyptra cucullate, smooth, 0.8-0.9 mm long.

Discussion:Fissidens flabellatus was long considered to be the same as F. asplenioides (Hampe, 1879), but these two species are quite different (Bruggeman-Nannenga et al., 1994). Fissidens flabellatus is separable from F. asplenioides by its more or less equal vaginant laminae, elimbate leaves, and, as seen in transverse section, the presence of 2 rows of enlarged cells in the distal part of the costa. The species is closest to F. petrophilus, a species restricted to the Greater Antilles. Plants of F. flabellatus, however, can be distinguished from F. petrophilus by their more or less equal vaginant laminae and shorter costae. In transverse section, the distal part of the costa of F. flabellatus shows 3 or 4 enlarged cells in each of 2 rows, whereas in F. petrophilus there are just 2 enlarged cells in each of 2 rows.
Distribution:Rio de Janeiro Brazil South America| Rio Grande do Sul Brazil South America| Santa Catarina Brazil South America| São Paulo Brazil South America|