Monographs Details: Fissidens yucatanensis Steere
Authority: Pursell, Ronald A. 2007. Fissidentaceae. Fl. Neotrop. Monogr. 101 (Published by NYBG Press)
Family:Fissidentaceae
Synonyms:Fissidens panamensis Pursell & B.H.Allen
Description:Species Description - Plants pale green. Stems monomorphic, unbranched, to 8 mm long x 2 mm wide; rhizoids basal, smooth, light tan; axillary hyaline nodules absent; epidermis and outer tier of cortical cells smaller than inner cortical cells, all thin-walled, hyaline; central strand present or absent; axillary, stalked, multicellular, clavate gemmae often present. Leaves crispate when dry, usually somewhat distant, as many as 12 pairs, lanceolate to ovate-lanceolate, oblanceolate or ligulate, acute to obtuse, usually ending in a clear, sharp cell, to 2 mm long x 0.45 mm wide, limbate on all laminae, limbidium ending below apex and above proximal ends of dorsal lamina, sometimes not differentiated on lower leaves, limbidial cells bi- to tris-tratose; costa narrowed distally, percurrent or ending 4-5 (-24) cells below apex, sometimes spurred distally, bryoides type; dorsal lamina narrowed gradually to insertion, not decurrent, ending in a few crenate marginal cells; vaginant laminae ± 1/2 leaf length, acute, equal; laminal cells eguttulate, ± thin-walled, conspicuously mammillose, irregularly quadrate to hexagonal, 10-24 µm long, patches of juxtacostal cells in proximal parts of vaginant laminae ± oblong, large, 70 µm long x 30 µm wide, pellucid. Monoicous (rhizautoicous); perigonial and perichaetial terminal on stems ± equal in length. Sporophytes, spores, and calyptra not known.

Discussion:Fissidens yucatanensis is characterized by a limbidium that narrows distally and ends below the leaf apex. The limbidium also ceases above the proximal part of the dorsal lamina which ends in a few crenate marginal cells. Laminal cells are clear, distinct, mammillose, and the cells in the proximal region of the vaginant laminae are enlarged, thin-walled, and pellucid. The species is closely related to F. angustifolius which has smaller, mammillose laminal cells, a limbidium that extends to or very near the base of the dorsal lamina, and a longer costa. Fissidens zollingeri, which can be confused with both F. angustifolius and F. yucatanensis, has smooth, slightly bulging laminal cells.
Distribution:Campeche Mexico North America| Jalisco Mexico North America| Quintana Roo Mexico North America| Veracruz Mexico North America| Orange Walk Belize Central America| Copán Honduras Central America| Guanacaste Costa Rica Central America| Colón Panama Central America| Panamá Panama Central America| La Habana Cuba South America| Santiago de Cuba Cuba South America| Independencia Dominican Republic South America| Pedernales Dominican Republic South America| Puerto Rico South America| Aragua Venezuela South America| Monagas Venezuela South America|