Monographs Details: Fissidens allionii Broth.
Authority: Pursell, Ronald A. 2007. Fissidentaceae. Fl. Neotrop. Monogr. 101 (Published by NYBG Press)
Synonyms:Conomitrium brunneolum Müll.Hal., Fissidens brunneolus (Müll.Hal.) Broth.
Description:Species Description - Plants light green, becoming reddish, particularly in stems and costae. Stems monomorphic, unbranched and branched, 4.0-5.5 mm long x l.50-1.75 mm wide; rhizoids basal and axillary, smooth, reddish; axillary hyaline nodules absent; epidermis and outer tier of cortical cells small, incrassate, pigmented; inner cortical cells larger, thin-walled, hyaline; central strand present. Leaves little changed when dry, tightly imbricate, as many as 18 pairs, narrowly lanceolate, acute, to 1.50 mm long x 1.50-1.75 mm wide; margin serrulate to ± entire, elimbate; costa percurrent to short-excurrent, conspicuously broad, bryoides type; dorsal lamina usually ending at insertion but sometimes ending above; vaginant laminae of cauline leaves ± 1/2-2/3 leaf length, acute, unequal, minor lamina ending ± 1/2 the distance between leaf margin and costa or rounded and distally free; laminal cells distinct, egut-tulate, frequently irregularly bistratose, firm-walled, mammillose, irregularly quadrate to hexagonal, 6-9 µm long, juxtacostal cells in proximal parts of vaginant laminae smooth, quadrate to narrowly linear, 15-40 µm long. Monoicous (gonioautoicous, infrequently rhizautoicous); perigonia gemmiform, axillary or terminal on gemmiform perigonial branches around base of longer stems; perichaetia terminal on short branches confined to leaf axils in lower half of larger stems, infrequently terminal on main stems; dorsal and ventral laminae of perichaetial and perigonial branches poorly differentiated or not, and costa long-excurrent. Sporophytes 1 per perichaetium, but 1 or more can be produced on a plant, yellow, darkening with age; seta smooth, 2.5-5.0 mm long; theca exserted, erect, radially symmetric, infrequently bilaterally symmetric, 0.400.55 mm long, stomatose, exothecial cells ± quadrate, collenchymatous; peristome scariosus type; operculum conic, long-rostrate, 0.4-0.5 mm long. Spores smooth, 7-9 µm diam. Calyptra cucullate, smooth, 0.4-0.5 mm long.

Discussion:It is remarkable that this species remained unrecognized for more than 50 years. Spruce collected specimens (Musci Amazonici et Andini 494, 495, 496) in both Ecuador and Peru. However, Mitten, who generally had a discerning eye with Fissidens, placed Spruce’s collections, along with one made by Weir in Colombia, in F. prionodes Mont. (Mitten, 1869; Spruce, 1867).

Fissidens allionii can be recognized by its tightly imbricate, narrowly lanceolate leaves, and broad, conspicuous, percurrent costa (the costa in the illustration of the lectotype is excurrent). Fissidens prionodes, a closely related species, differs not only in having a narrower, less conspicuous costa that is usually short-excurrent but also in the location of the perichaetia and perigonia. In F. allionii the perichaetia are terminal on short axillary branches, confined more or less to the proximal halves of larger stems, whereas in F. prionodes the perichaetia are terminal on main stems. However, F. allionii can occasionally exhibit a terminal sporophyte. Perigonial stems in both species are gemmiform, but in F. allionii they are usually axillary while in F. prionodes, for the most part, they are found around the base of perichaetial stems. Both species have mammillose laminal cells that are frequently bistratose.
Distribution:Napo Ecuador South America| Sucumbíos Ecuador South America| Saint-Laurent-du-Maroni French Guiana South America| Mazaruni-Potaro Guyana South America| Darién Panamá Central America| Amazonas Colombia South America| Amazonas Venezuela South America| Para Suriname South America| Loreto Peru South America| Madre de Dios Peru South America| Acre Brazil South America| Amazonas Brazil South America| Pará Brazil South America| Rondônia Brazil South America|