Monographs Details: Fissidens hyalinus Hook. & Wilson
Synonyms:Conomitrium hyalinum (Hook. & Wilson) Müll.Hal., Schistophyllum hyalinum (Hook. & Wilson) Lindb.
Description:Species Description - Plants pale green. Stems monomorphic, delicate, unbranched, to 5 mm long x 3 mm wide; rhizoids basal, smooth, pale; axillary hyaline nodules absent; epidermis and cortical cells large, thin-walled, hyaline; central strand absent. Leaves crispate when dry, loosely imbricate, palmately to pinnately arranged, as many as 6 pairs, lanceolate, obtuse to acute, sometimes apiculate, to 2.2 mm long x 0.5 mm wide, perichaetial leaves largest; margin entire, sometimes serrulate at apex, limbate, limbidium on all laminae, weak and narrow, 1-2 cells wide, ending below apex, distinct on dorsal and ventral laminae, often indistinct on vaginant laminae, limbidial cells unistratose; ecostate; dorsal lamina narrowed, ending at insertion; vaginant laminae 1/3-1/2 leaf length, acute, equal; laminal cells eguttulate, unistratose, thin-walled, shrinking greatly when dry, smooth, hexagonal to elongate-hexagonal, 31-67 µm long x 14-34 µm wide. Monoicous (rhizautoicous); perigonia stems gemmiform at base of perichaetial stems or terminal on stems as long as perichaetial stems; perichaetia terminal. Sporophytes 1 per perichaetium, yellow, darkening with age; seta smooth, 2.5-3 mm long; theca exserted, erect, radially symmetric, infrequently somewhat arcuate, bilaterally symmetric, 0.54-0.5 mm long, stomatose, exothecial cells quadrate to oblong, collenchyma-tous; peristome scariosus type; operculum conic, long-rostrate, ± 0.4-0.5 mm long. Spores finely papillose, 9-13 µm diam. Calyptra mitrate, smooth to ± bulging, 0.4 mm long.
Discussion:A synonym from outside the area of this study (Iwatsuki & Haji Mohamed, 1987): Fissidens nymanii M. Fleisch.Fissidens hyalinus and F. ecuadorensis are the only two ecostate or nearly ecostate species in the Neotropical bryoflora. Plants of both species are very small and delicate, and for these reasons are probably overlooked in the field. Fissidens hyalinus can be distinguished from F. ecuadorensis by its limbidium that is 1-2 cells wide and 1 cell in thickness. The limbidium usually ends short of the leaf apex and is weak on the vaginant laminae. Laminal cells of F. hyalinus, on the average, are smaller than those of F. ecuadorensis.
Michoacán Mexico North America
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