Mnioloma Herzog
Mnioloma Herzog, Ann. Bryol. 3: 119. 1930.
Calypogeia subg. Mnioloma (Herzog) Bisch., Candollea 18: 25. 1963 (1962).
Type: Mnioloma rhynchophyllum Herzog
Plants dull, opaque, light brown to yellowish brown to golden, the stems deeper brown, the shoots markedly flat. Branching irregular, the branches all ventral-intercalary, leafy or stoloniform and long, geotropic, microphyllous and copiously rhizoidous. Stem with cortex in 1(2) rows of firm- to thick-walled cells slightly smaller than those of the medulla; medullary cells thin-walled, hyaline. Rhizoids normally lacking on leading leafy shoots, typically only present at bases of underleaves and leaves of stoloniform branches. Leaves dull (but the border at times nitid), notably plane, ovate-deltoid to (mostly) oblong-ovate to oblong, the apex typically rounded, contracted to a beaked or pointed tip (Mnioloma rhynchophyllum), unlobed or (M. retusa) retuse to shallowly bilobed; leaves with a border of differentiated cells (rarely feebly developed or lacking), the border cells slightly to conspicuously elongated either at right or oblique angles to the margin, in some species the margin crenulate to denticulate by projecting free ends of the marginal cells, the cells of the border often thicker-walled, lacking oil-bodies and chloroplasts, and with a smooth surface. Cells (intramarginal) thin- to feebly firm-walled, trigones small to exceptionally bulging and nodulose; surface papillose. Oil-bodies usually lacking in marginal cells, (1)2–11(13) per cell, colorless to smokey grey to brownish grey, finely botryoidal. Underleaves delicate, hyaline and echlorophyllous, orbicular-ovate to elongate-ovate, ± convex (ventral view); apex mostly feebly emarginate or a mere weak notch, the vestigial, closely juxtaposed lobes each reduced to a slime papilla, the sinus very small, the underleaves bilobed to 0.6 in a few species; cells thin-walled, usually markedly elongated, often ± prosenchymatous at the margins, the marginal cells often widest at the radial walls and with the intervening free wall arched toward the cell lumen, the margins thus appearing scalloped. Asexual reproduction lacking.
Dioecious. Androecia on very short, ventral-intercalary branches ± hidden in axil of underleaves, compact; bracts in 1–2 pairs, bilobed. Marsupium fleshy, cylindrical, brownish, rhizoidous, the summit with a few, vestigial bractlets.
Capsule cylindrical, the valves spirally twisted, linear, outer layer of cells markedly elongated, with two-phase development: primary longitudinal and transverse walls lacking thickenings, the secondary longitudinal walls with thickenings feebly sinuous-nodular; inner layer of cells with semiannular bands narrow, complete or, mostly, incomplete.
Spores granular. Elaters tortuous, bispiral.
A pantropical genus of ca. 13 species, 11 of which are restricted to the Neotropics and mostly occur in northern South America, Central America and the West Indies. The genus is absent from southern South America. Mnioloma fuscum (Lehm.) R.M.Schust. has a broad pantropical distribution that includes South Africa and New Guinea. Mnioloma novae-zelandiae is endemic to our area.
References: Engel (2006c), Renner (2003), Schuster (1995c, 2000a).
