Monographs Details: Hypnella guayanensis B.H.Allen & W.R.Buck
Authority: Buck, William R. 1990. Contributions to the moss flora of Guyana. Mem. New York Bot. Gard. 64: 184-196.
Family:Pilotrichaceae
Description:Distribution and Ecology - Allen & Buck, n. sp. Type.G U Y A N A . Upper Potaro River Region: Mt.Wokomung base camp and vie, 05°05'N,59°50'W, 1070 m , moist tropical forest, epiphytic,8 Jul 1989, B o o m & Samuels 9131(holotype N Y , isotypes B R G , M O ) . Paratypes.G U Y A N A . Upper Potaro River Region:Wokomimg base camp and vie, 05°05'N,59°50'W, 1070-1160 m , moist forest on plateau,epiphytic. B o o m & Samuels 9001 (BRG,M O , N Y ) ; Upper Mazaruni River Region:Karowtipu Mountain, 05°45'N, 60°35'W, 920-1080 m , between camp and peak on westemside of mountain, epipetric. B o o m & Gopaul7708 (BRG, M O , N Y ) , north slope of MountRoraima, 05°17'N, 60°46'W, 700-1000 m,mossy forest in valley of rivulet, on rotten log,Gradstein 5208 ( M O , N Y , U ) . V E N E Z U E L A.Bolivar: Cerro Venamo (parte sur-oeste),Steyermark, Dunsterville & Dunsterville 92240

Discussion:

Species nova Hypnellae pallescenti proxima, differt praecipue foliis ecostatis. Plants small to medium sized in shiny, reddish- yellow to pale green mats. Stems red, creeping, densely and irregularly or subpinnately branched, central strand absent; axillary hairs 2-celled, the basal cell quadrate, red-brown, the upper cell swollen, ovate, hyaline. Stem leaves erect, widely spaced, ovate, broadly acute, 0.7- 1.0 X 0.4-0.5 m m ; branch leaves erect-spreading to weakly homomallous, dense, oblong-lanceolate, bluntly acute, 0.6-0.9 x 0.2-0.3 m m , concave; margins erect to broadly incurved, entire or with a few small, widely spaced serrations; ecostate; cells linear-flexuose, 60-100 x 4-7/,µm thick-walled and porose or firm- to thin-waUed, smooth or pluripapillose, the papillae simple or branched; alar cells absent. Autoicous. Setae redbrown, 1.5-2.5 c m long, smooth or densely papillose above; capsules red, inclined, oblong-cylindric, strongly tuberculate at base; exothecial cells strongly coUenchymatous; opercula shortly rostrate, 1.0 m m long; exostome teeth red, on front surface densely cross-striolate with prominent median furrow; endostome yellow, segments on a high basal membrane exceeding the length ofthe teeth, cilia absent. Spores spherical, 12-15 µm in diam. Calyptrae mitrate, spHt at base. This species is close to Hypnella pallescens (Hook.) Jaeg. and both species are present in the Guayana Highland of South America. It differs most significantly in its ecostate leaves and the variable expression of its leaf papillae. Although the costa in H. pallescens is short for the genus (V3 to Vi the leaf length), it is always present. Likewise the pluripapillose leaf cells of H. pallescens are typically multifid, giving the plants a characteristic glaucous appearance. Plants of H. guayanensis do not have this glaucousness and leaf cell ornamentation is phenomenally variable. All the leaf cells on a plant can be smooth, have low unbranched papillae, or have multifid papillae. The leaf cells on some plants m a y have a combination of the above, i.e., some leaves with smooth cells and some leaves with various types of papulae. Furthermore, the leaves on some plants m a y have smooth leaf cells in the lower half and papUlose leaf cells in the upper half of the leaf. W h e n the leaves are completely smooth, they are strongly concave and the leaf cells are thick-walled and porose with blunt ends. The more papiUose the leaf cells are, the more thinwaUed and sharper-ended they are, and the leaves are less concave. The type specimen primarUy has smooth leaf cells but some plants and some branches of some plants have papillose leaf cells. There are two distinct morphologies present within H. guayanensis. One, noted by Robinson (1965), consists of small-leaved plants that have intricately branched stems arising from a massive stolon. This form also has papillose setae over 2 c m long. In typical H. pallescens the setae are smooth and less than 1.8 c m long. The second morphology ofH. guayanensis consists of larger plants that are weakly and irregularly branched, do not have massive stolons, and have shorter, smooth setae. This morphology is more commoiUy encountered with entirely smooth leaf ceUs than the first. It m a y be that these two forms represent discrete entities, but there are a few collections that are intermediate in expression. A decision on the status of these two morphologies should be postponed until the species is better known.

Distribution:Guyana South America| Venezuela South America|