Monographs Details: Fissidens hydropogon Spruce ex Mitt.
Authority: Pursell, Ronald A. 2007. Fissidentaceae. Fl. Neotrop. Monogr. 101 (Published by NYBG Press)
Synonyms:Octodiceras hydropogon (Spruce ex Mitt.) A.Jaeger, Conomitrium hydropogon (Spruce ex Mitt.) Paris
Description:Species Description - Plants dark green to brownish-black, aquatic, submerged but periodically emergent (?), in dense mats. Stems monomorphic, profusely branched, to 100 mm [10 cm] long x ± 3 mm wide; rhizoids basal, few, smooth, reddish, absent from proximal ends of branches; axillary hyaline nodules present; epidermis and outer 1-3 tiers of cortical cells small, incrassate, pigmented; inner cortical cells larger, hyaline, mixed with incrassate cells; central strand absent. Leaves changed little when dry, imbricate, in numerous pairs, broadly lanceolate, acute, to ± 2.5 mm long x ± 0.7 mm wide; margin ± entire, limbate on proximal 1/3 or less of vaginant laminae of perichaetial and immediate subtending leaves, limbidium weak, limbidial cells unistratose; costa ending 2-6 cells below leaf apex, bryoides type; vaginant laminae 4/5 or more the leaf length, acute, ± unequal; laminal cells distinct, eguttulate, unistratose or irregularly bistratose, firm-walled, smooth, ± bulging, irregularly quadrate to hexagonal, 10-12 µm long, somewhat larger in proximal parts of vaginant laminae. Monoicous (gonioautoicous); perigonia gemmiform, axillary; perichetia terminal on stems and branches, naked archegonia in axils of leaves immediately below perichaetia. Sporophytes 1 per perichaetium, numerous, reddish; seta smooth, short, 0.5 mm or less long; theca immersed to emergent, erect, radially symmetric, 0.5-0.9 mm long, stomatose or estomatose, exothecial cells quadrate to oblong, vertical walls thicker than horizontal walls; peristome teeth reduced bryoides type, fenestrate or incompletely divided, with delicate spiral ornamentation distally; operculum conic, short-rostrate, 0.2-0.5 mm long. Spores smooth, 22-27 µm diam. Calyptra mitrate, smooth, with 1-2 short vertical slits, covering only the rostrum.

Discussion:Fissidens hydropogon, known from a single site in Ecuador, is characterized by its profuse branching, lack of rhizoids at the base of tightly attached branches, a limbidium restricted to the proximal 1/3 or less of the perichaetial and subtending leaves, immersed to emergent capsules, and reduced bryoides type peristome. The species might be confused with F. geijskesii, which is known from a single site in Suriname, and which differs principally in its elimbate leaves, taxifolius type costa, regularly pluristratose lamina cells, and anomalous peristome.
Distribution:Ecuador South America|