Monographs Details: Fissidens angustelimbatus var. angustelimbatus
Authority: Pursell, Ronald A. 2007. Fissidentaceae. Fl. Neotrop. Monogr. 101 (Published by NYBG Press)
Synonyms:Fissidens angustelimbatus Mitt., Conomitrium angustelimbatum (Mitt.) A.Jaeger, Conomitrium smaragdinum Lorentz & Müll.Hal., Fissidens smaragdinus (Lorentz & Müll.Hal.) Broth., Fissidens falcatus Wilson, Fissidens variabilis Brugg.-Nann., Fissidens fossicola Müll.Hal., Fissidens protracticaulis Broth., Fissidens goebelii Müll.Hal., Conomitrium goebelii Müll.Hal., Fissidens leptocaulis Müll.Hal., Fissidens malmei Broth., Fissidens pennula Broth., Fissidens mattogrossensis Broth., Fissidens angustelimbatus var. brevisetus Broth., Fissidens capillisetoides Brugg.-Nann.
Description:Variety Description - Plants pale to dark green, often encrusted with diatoms and blackish detritus. Stems monomorphic, unbranched or branched, quite variable in size, 240mm long x 1.5-3.5 mm wide; rhizoids basal and axillary, smooth, reddish; axillary hyaline nodules absent; epidermis and outer 1-3 tiers of cortical cells small, incrassate, usually pigmented; inner cortical cells larger, thin-walled, hyaline; central strand absent; stalked, multicellular, clavate gemmae infrequently produced in axils of branch leaves. Leaves crispate when dry, distant to tightly imbricate, as many as 60 pairs, ovate to oblong, obtuse to ± rounded, usually mucronate to short-cuspidate, 1.3-2.2 mm long x 0.4-0.6 mm wide, lower ones often eroded with only costa and limbidium remaining; margin ± entire, often serrulate distally, limbate on all laminae, limbidium ending 2 or more cells below leaf apex or confluent at leaf apex, ending at or above insertion of dorsal lamina, sometimes poorly developed on or absent from dorsal and ventral laminae, limbidial cells uni- to tristratose; costa usually percurrent to short-excurrent or ending 2-4 cells below leaf apex, bryoides type; dorsal lamina narrowed to insertion, ending at insertion or short-decurrent; vaginant laminae of cauline leaves 2/3-4/5 leaf length, acute, ± equal; laminal; cells, distinct, eguttulate, unistratose, firm-walled, smooth, ± bulging, irregularly quadrate to hexagonal, in transverse section about as deep as wide, mostly longer than wide, 6-16 µm long x 6-14 µm wide, somewhat larger in proximal parts of vaginant laminae. Monoicous (gonioautoicous, rarely rhizautoicous); perigonia axillary or terminal on stems; perichaetia terminal on stems and branches. Sporophytes 1-2 per perichaetium, reddish, infrequent; seta smooth, 2.5-5.0 mm long; theca exserted, arcuate, bilaterally symmetric or erect, radially symmetric, 0.7-1.0 mm long, stomatose, exothecial cells quadrate to oblong, vertical walls thicker than horizontal walls; peristome bryoides type; operculum conic, short-rostrate, to 0.7 mm long. Spores finely papillose, 11-25 µm diam. Calyptra not seen.

Discussion:A specimen (Buck 33118, NY) collected in French Guiana might belong to this species, but it is in such poor condition that a positive identification cannot be made.

As is the case with many aquatic mosses, Fissidens anguste-limbatus varies considerably in size; the shortest stems are approximately 8 mm long while the longest are about 40 mm [4 cm]. Aside from its aquatic habitat, although at times the plants are emergent because of fluctuations in water level, the species is distinguished by a number of features. In the majority of specimens the costa extends into a mucro. The limbidium is narrow, although in one specimen (Yano 2290, MO) it reaches 27 µm in width. In most instances the limbidium extends to the apex of the leaf or ends 2-3 cells below the apex. In the holotype of F. anguste-limbatus and the lectotype of F. smaragdinus the limbidium ends 5 or more cells below the leaf apex. In the holotype of F. anguste-limbatus the limbidial cells are uni- or bistratose. However, in most other instances, the limbidial cells are bistratose, but in the types of F. goebelii and F. capillisetoides they can be tristratose. The limbidium can reach the insertion of the dorsal lamina or cease somewhat above the insertion. Laminai cells are usually distinct, unless obscured by diatoms or other encrustation, and are somewhat longer than wide. In transverse section the depth of the laminal cells do not exceed their width.

Fissidens anguste-limbatus var. anguste-limbatus is closest to F. oediloma and is distinguished by the thickness of its limbidium and the length of its vaginant laminae relative to the length of the leaf.

As plants begin to age, they develop a dark-brown to black pigmentation, especially in the costa and limbidium. Often the proximal leaves are eroded; the costa and limbidium are the only parts to persist. The presence of gametangia and sporophytes is the exception rather than the rule; sporophytes were seen in approximately 50% of the specimens examined. The formation of axillary gemmae is probably a response to environmental stress; these structures were seen in only one specimen and do not differ in appearance from gemmae found in several other Neotropical Fissidens.
Distribution:Upper Takutu-Upper Essequibo Guyana South America| Distrito Federal Mexico North America| México Mexico North America| Chiriquí Panamá Central America| Caquetá Colombia South America| Amazonas Venezuela South America| Marowijne Suriname South America| Sipaliwini Suriname South America| Loreto Peru South America| Acre Brazil South America| Amazonas Brazil South America| Distrito Federal Brazil South America| Goiás Brazil South America| Maranhão Brazil South America| Minas Gerais Brazil South America| Pará Brazil South America| Paraná Brazil South America| Rio Grande do Sul Brazil South America| Rondônia Brazil South America| Roraima Brazil South America| São Paulo Brazil South America| Cordillera Paraguay South America| Buenos Aires Argentina South America| Córdoba Argentina South America| Canelones Uruguay South America| Montevideo Uruguay South America| Paysandú Uruguay South America| Delta Amacuro Venezuela South America|