Monographs Details: Fissidens scalaris Mitt.
Synonyms:Fissidens distichellus Besch., Fissidens hauthalii Müll.Hal., Fissidens semi-lamellosus Müll.Hal., Fissidens hauthalii var. minor Müll.Hal., Fissidens colonialis Müll.Hal., Fissidens hauthalii var. obtusatula Müll.Hal., Fissidens hauthalii var. angustissimus Müll.Hal., Fissidens stoloniferus Müll.Hal., Fissidens tener Dusén, Fissidens felipponei Broth., Fissidens antennidens Müll.Hal. ex Broth., Moenkemeyera neonii E.B.Bartram, Fissidens neonii (E.B.Bartram) Grout, Fissidens sehnemii E.B.Bartram
Description:Species Description - Plants pale green. Stems dimorphic, delicate, unbranched or branched from older parts, infertile ones to 6.0 mm long x 1.0 mm wide, fertile ones shorter, 1.5-2.0 mm long x 1.0 mm wide; rhizoids basal and axillary, smooth, brownish; 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 changed little when dry, distant to imbricate, as many as 16 pairs on infertile plants, fewer on fertile plants, oblong to lanceolate, acute to short-acuminate, to 1.3 mm long x 0.25 mm wide, perichaetial leaves longest; margin ± entire to crenulate-serrulate, limbate on all laminae, limbidium variable, developed best on vaginant laminae, ceasing well below leaf apex, often lacking from most dorsal and ventral laminae, limbidial cells unis-tratose; costa ending 2-5 cells below apex to percur-rent, bryoides type; dorsal lamina narrowed, ending well above insertion or reaching insertion; vaginant laminae of cauline leaves ± 4/5 leaf length, acute, ± equal, very broad in perichaetial leaves; laminal cells distinct, eguttulate, unistratose, firm-walled, smooth, plane or slightly bulging, irregularly quadrate to rhombic, 9-14 µm long x 4-9 |xm wide, increasing in size, to 32 µm long x 11 |im wide, and becoming ± oblong toward proximal parts of vaginant laminae. Monoicous (rhizautoicous, cladautoicous); perigo-nial stems gemmiform at base of fertile and infertile stems, and perigonia terminal on branches along horizontal parts of stems. Sporophytes 1 per perichaetium, yellow, darkening with age; seta smooth, 2-6 mm long; theca exserted, erect, radially symmetric, 0.50-1.25 mm long, stomatose, exothecial cells quadrate to oblong, vertical walls somewhat thicker than horizontal walls; peristome anomalous, reflexed when dry, inflexed when wet, fragile, variable even in same capsule, either undivided or imperfectly divided or divided 4/5 their length, distally papillose, proximally smooth; operculum conic, short-rostrate, 0.22-0.30 mm long. Spores finely papillose, 20-36 µm diam. Calyptra smooth, cucullate, to 0.45 mm long.
Discussion:This tiny Fissidens is best distinguished from other species with dimorphic stems by its peristome, the teeth of which, even in the same theca, can be undivided, imperfectly divided or divided for much of their length. The distal parts of the teeth are papillose while the proximal parts are smooth. The sporophyte appears to be relatively large for the gametophyte.
Michoacán Mexico North America
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