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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



[VOL. 11 



VENEZUELA: Estado Bolivar: Auyan-tepui, canyon, 2150-2200 m, Steyermark 91fiJfl 

 (type, NY). 



Because of its nearly radial form the species suggests M. grandistipulum 

 but is at once distinguished from the latter because of the stiff habit, the 

 leaves with a long wing on a sharp keel, and the very large mamillae of the cells. 



17. Micropterygium conchifolium Reimers, Hedwigia 73: 155. /. 5. 1933. 



Leafy stems of small to medium size, compact, in mats or scattered among 

 other bryophytes, yellow-brown to dark green, ascending from a branched rhizome 

 system; stems to 1.5 mm long, with leaves, 0.8-1.2 mm broad, lateral branches 

 occasional. Leaves spreading, ascendent in the outer part, broadly ovate, more 

 or less concave, 0.8-1.0 mm long, keeled in the upper part, the wing of two to 

 four rows of cells extending from near the apex to the middle of the leaf or less, 

 the margin undivided, crenulate from projecting cell walls; cells of the apical 

 portion round-quadrate, 10-13 n, the walls thin, the trigones distinct; the surface 

 plane, the cuticle smooth. Underleaves large, orbicular to obovate-rounded, 

 broader than the stem, the upper margin entire or rarely obscurely toothed, the 

 cells and margin as in the leaf. Inflorescences and sporophyte not seen. PI. 64. 

 Fig. 17, a-d. 



Habitat: Shaded sandy banks along streams and on wet sandstone cliffs. 



VENEZUELA: Estado Bolivar: Auyan-tepui, tributary of Rio Churun, 1760 m, 

 Steyermark 93355 (lectotype VEN) ; Rio Churun, 1660 m, Steyermark 93792 p.p., 93819 (VEN). 

 Mt. Duida, 2000 m, Tate 514 ("Type, NY; cotype B"— but apparently lost). 



18. Micropterygium tumidulum Fulford, sp. nov. 



Caules foliosi parvi, graciles, compacti, 0.5-1 cm longi; folia symmetrica, 

 concava, inflata, patenti-ascendentia, apice sursum curvato, marginibus integris, 

 ala parva nonnunquam praesenti in parte superiore; cellulae 15x15 n, parietibus 

 incrassatis, trigonibus magnis lateribus convexis, luminibus angulari-rotundis, 

 cuticulo aspero-verruculoso verrucis magnis rotundis. 



Leafy stems small, compact, slender, greenish to yellow-brown, prostrate to 

 ascendent from a branched rhizome system; stems 0.5-1 cm long, with leaves to 

 0.5 mm broad, often abundantly branched, the branches at first radial with 

 small, orbicular leaves and underleaves, becoming larger, dorsiventral with 

 obscure underleaves in the upper two-thirds, or occasionally flagelliform. Rhizoids 

 on the scale-leaves of the rhizome and the flagelliform branches. Leaves densely 

 imbricate, symmetric, concave, strongly inflated, spreading, becoming ascendent 

 in the outer part, the apex curved upward, often bifid by a pair of cells, a short, 

 narrow wing sometimes present, the margins entire; cells quadrate in outline, 

 mostly 15 x 15 n, the walls thickened, trigones large with bulging sides, the 

 lumina angular-rounded, the cell surface covered with rounded to elongate warts 

 as in the genus Mytilopsis. Underleaves of the base of the shoot rounded, as 

 broad as the stem, becoming progressively smaller upward, reduced to only a few 

 cells near the stem tip. Female branches frequent, short, several on the lower 

 part of a stem or the rhizome, the bracts and bracteoles ovate to ovate-lanceolate, 

 the lateral margins of the inner series serrate and dentate, the apical part of 

 several long laciniae. Male branches, perianth and sporophytes not seen. 

 PI. 64. Fig. 18, a-d. 



Habitat: Moist base of sandstone escarpment. 



