Monographs Details: Fissidens rochensis Broth.
Synonyms:Fissidens jimenezii E.B.Bartram
Description:Species Description - Plants bright green distally, usually brown-black proximally. Stems monomorphic, infrequently branched, 3-20 mm [0.3-2.0 cm] x 1.0-2.0 mm wide; rhizoids basal, 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 or absent. Leaves little changed or ± crispate when dry, imbricate to distant, as many as 33 pairs, lanceolate, obtuse to acute, to 1.6 mm long x 0.2-0.3 mm wide; margin entire or serrulate above, limbate on all laminae, limbidium ceasing below leaf apex and above insertion of dorsal lamina, limbidial cells uni- or bistratose; costa percurrent to ceasing 4 cells below leaf apex, bryoides type; dorsal lamina narrowed distally, reaching insertion or infrequently slightly decurrent; vaginant laminae of cauline leaves ± 1/2 or more leaf length, acute, ± equal; laminal cells distinct, egut-tulate, irregularly to ± regularly bistratose, firm-walled, smooth, plane to slightly bulging, irregularly hexagonal, 7-10 µm. Monoicous (cladautoicous); perigonia and perichaetia terminal on stems and branches. Sporophytes 1 per perichaetium, reddish; seta smooth, 3.0-7.0 mm long; theca exserted, inclined, bilaterally symmetric, to 0.7 mm long, stomatose, exothecial cells quadrate to oblong, collenchy-matous; peristome bryoides type; operculum conic, short-rostrate, 0.3-0.4 mm long. Spores finely papillose, 14-20 µm diam. Calyptra cucullate, smooth, to 0.5 mm long.
Discussion:Fissidens rochensis appears to be quite responsive to variations in its habitat. In its typical expression (Duss 116), the species is reminiscent of a small F. grandifrons, and is adapted to rapidly moving water. Leaves of both these species are similar in shape and thickness, although F. rochensis is limbate while F. grandifrons is elimbate. This expression of F. rochensis is characterized by leaves in which the dorsal and ventral laminae are narrow and essentially bistratose. At the other extreme, and interconnected by intermediates, e.g., Allard 18453 and Buck 14224 from the Dominican Republic and an expression from Puerto Rico, Buck 21107, the species has broader dorsal and ventral laminae in which the juxtacostal cells are bistratose but those elsewhere are only irregularly bistratose. Such expressions can be confused with F. bryoides, which can be distinguished by laminal cells that are typically unistratose and only rarely irregularly bistratose. The sporophyte of F. rochensis, with its long seta, is typical of terrestrial species of Fissidens.
Distribution:Dominica South America
| Santiago de Cuba Cuba South America
| Jamaica South America
| La Vega Dominican Republic South America
| San Juan Dominican Republic South America
| Puerto Rico South America