Monographs Details: Fissidens juruensis Broth.
Synonyms:Fissidens brittonii Grout, Fissidens brittonii var. percurrens Grout, Fissidens juruensis var. percurrens (Grout) Pursell
Description:Species Description - Plants pale to dark green. Stems monomorphic, unbranched to sparingly branched, to 10 mm [1 cm] long x 4.5 mm wide; rhizoids basal and axillary, smooth, reddish; axillary hyaline nodules absent; epidermis and outer cortical cells smaller than inner cortical cells, all thin-walled; central strand present or absent. Leaves crispate when dry, often palmately arranged, as many as 10 pairs, lanceolate to oblong, obtuse-apiculate to acute, to 3 mm long x 0.7 mm wide, usually smaller; margin usually evenly and bluntly crenate to crenulate-serrulate, limbate and ± entire on vaginant laminae, limbidium weak, confined to proximal 1/2 of vaginant laminae, limbidial cells unistratose; costa ending well below apex to percur-rent, bryoides type, reduced distally; dorsal lamina narrowed proximally, ending at insertion; vaginant laminae ± 1/2 leaf length, acute, ± equal, minor lamina ending on leaf margin or nearly so; laminal cells distinct, eguttulate, smooth, unistratose, thin-walled, shrinking greatly when dry, distal ones ± quadrate, oblong, pentagonal or irregularly oblong-hexagonal, 11-49 µm long x 11-15 µm wide, marginal ones smaller, juxtacostal ones in proximal part of vaginant laminae larger, to 72 µm long x l8 µm wide, ± pellucid. Monoicous (rhizautoicous); perigonia terminal on short stems; perichaetia terminal on stems usually longer than perigonial stems. Sporophytes 1-2 per perichaetium, yellow, darkening with age; seta smooth, to 9 mm long; theca exserted, usually ± arcuate, often ± pendant, bilaterally symmetric, to 0.6 mm long, stomatose, exothecial cells quadrate to oblong, vertical walls thicker than horizontal walls, collenchymatous; peristome scariosus type; operculum conic, long-rostrate, to 0.6 mm long. Spores smooth, 7-11 pm diam. Calyptra smooth, cucullate, to 0.6 mm long.
Discussion:Fissidens juruensis is distinguished by large, thin-walled laminal cells that decrease in size toward the margin, large, oblong, pellucid, juxtacostal cells in the proximal parts of the vaginant laminae, a weak limbidium limited to the proximal 1/2 or less of the vaginant laminae of most leaves, a long seta, and an arcuate, bilaterally symmetric theca that is often more or less pendant. The laminai cells are usually very difficult to rehydrate once they have been hydrated and then allowed to dry. The species has been confused with F. inaequalis (Pursell, 1999b), which differs by its easily rehydrated laminal cells, elimbate vaginant laminae that are broad and retuse in the perigonial and perichaetial leaves, shorter seta, and erect, radially symmetric theca.
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