274 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



[VOL. 11 



VENEZUELA: Est ado Bolivar: Auyan-tepui, along Rio Chimin, 1660 m, Steyermark 

 93792 (type NY). 



This species shows a combination of the characters of several other members 

 of the genus. The tendency toward a decrease in size of the underleaves from 

 the base to the tip of the leafy stem is characteristic of several species. The 

 size and general habit of the plant suggests M. exalatum of Puerto Rico and 

 Dominica but differs particularly in the very large warts of the cuticle. In 

 M. exalatum the cuticle has very small, scarcely noticable verruculae. 



The cells and warty cuticle are like those of plants of the monotypic 

 Mytilopsis albifrons. Furthermore, in the latter, on the smaller-leaved lower 

 part of a leafy branch (a reversion), the leaves are inflated, and large, orbicular 

 underleaves are present. In the adult stems of Mytilopsis in contrast, the leaves 

 are flat, complicate, equitant, and deeply bifid. Underleaves are absent. 



Taxa Not Available for Study 

 Micropterygium angustistipulum Spruce, Mt. Campana, Peru. 



References 



Herzog, Th. 1944. Micropterygium reimersianum Herzog, Eine neue Art der Gattung aus 



Slid brasilien. Hedwigia 81 : 225-228. /. /. 

 Lindenberg, J. B. G. & Gottsche, C. M. 1851. Species Hepaticarum VIII-XI. pp. 114-118. 



pi. 21. 



Reimers, H. 1933. Revision der Lebermoosgattung Micropterygium. Hedwigia 73: 133-204. 



/. 1-20. 



. 1936. Nachtrag zur Revision der Lebermoosgattung Micropterygium. Ibid. 76: 



165-168. 



Spruce, R. 1876. On Anomoclada, a new genus of Hepaticae, and on its allied genera, 

 Odontoschisma and Adelanlhm. London Jour. Bot. 14: 162, 164, 195. 



Mytilopsis Spruce, On Cephalozia p. 90. 1882. 



The characters of this monotypic genus are those of the species as given below. 

 Type species: M ytilopsis albifrons Spruce. 



1. Mytilopsis albifrons Spruce, Trans. Proc. Bot. Soc. Edinb. 15: 387. pi. 14. 

 1885. 



Leafy stems complanate, ascendent from a prostrate, branched rhizome 

 system, yellow to dark brown, in mats or among other bryophytes; stems 1-2 cm 

 long, with leaves, to 0.7 mm broad, simple or branched, the branches ventral, 

 leafy or flagelliform ; in transverse section the stem with a cortical layer of 

 usually 12 rows of large cells with very thick yellow-brown walls surrounding a 

 medulla of large, colorless thin-walled cells. Rhizome branches rhizome-like, or 

 flagelliform, with scale-leaves, or radial with small orbicular leaves and under- 

 leaves, or complanate leafy without underleaves. Rhizoids in tufts on the 

 scale-leaves of rhizomes and flagelliform branches. Line of leaf insertion short, 

 transverse, the leaf-base of 12 elongate cells. Leaves equitant-imbricate, widely 

 spreading, bilobed, equally folded, flat, the keel sharp, a wing not developed (at 

 most of only one row of cells), the basal auricles extending across the stem and 

 beyond on both the dorsal and ventral sides, the apex subtruncate with an 

 ascendent tip, the margins dentate, in the upper part often erose; leaf cells 

 quadrate in outline, the trigones large with bulging sides, the outer surface 



