Macromitrium costaricense E. B. Bartram

Macromitrium costaricense E. Bartr. Contr
U. S. Nat. Herb. 26: 88. 1928.
Plants in dense tufts, brownish below, yellowish-green above; secondary stems erect, branched, somewhat radiculose below, about 2 cm. high; leaves cirrhate-crisped when dry, flexuous-spreading when moist, about 3 mm. long, linear-lanceolate, short-acuminate, serrulate only toward the apex, carinate and slightly plicate below; costa excurrent into a short, denticulate point; upper leaf-cells rounded-quadrate to oblong, not very thickwalled, 7-10 fi in thenlongest dimension, smooth, in not very apparent rows; median cells more elongate, the lower long and narrow with thick, yellowish, sinuate walls, smooth or with a few low, rounded papillae; perichaetial leaves about 4 mm. long, narrower and more slenderly acuminate than the stem leaves, their cells more elongate, their costa longer-excurrent ; ? autoicous; seta 8-10 mm. long, smooth or bearing a few low papillae; capsules ovoid, contracted to a short, sulcate neck, the urn about 1.5 mm. long; calyptra smooth, deeply laciniate; operculum rostrate, a little shorter than the urn; peristome double.
Type locality: On tree, La Palma, Province of San Jose, Costa Rica (Standley 30823; type in herb. Bartram examined).
Distribution: Known only from the type locality.