132 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



[vol. 10 



3. Lorostemon colombianus Maguire, Bot. Mus. Leafl. 18 : 159. 1958. 



Type. Rio Ricapuya, Rio Apaporis, Amazonas, Colombia, Schultes & Cabrera 

 17638 (holotype NY). Paratype. Same locality, Schultes & Cabrera 17619 (NY). 



Distribution. So far collected only in the Rio Vaupes basin, Comisaria Vaupes, 

 Colombia, and Igarape Caburi, Rio Negro, Amazonas, Brazil (Froes 28729, NY). 



4. Thysanostemon Maguire, gen. nov. 



Sepala 5, cyclica quincunciala ; petalis 5, sepalis oppositis, dextrorse im- 

 bricatis, lineari-oblongis ; antheris 25 minusve in quinque phalangibus aggregatis, 

 filamentis ex toto in ligulo connatis, antheris extrorsis ; gynobasi prominent! ; 

 ovario 5-loculari, sessili ; ovulis pluribus axillaribus ; stylo non differenti. 



Arbor parva latice pallido, moderato ; ramulis tenuibus ; f oliis oppositis. 



Type. Thysanostemon pakaraimae Maguire. 



The name from thysanos, dvaavos, fringe, and stemon, arrj^cov, stamen. 



Key to the Species of Thysanostemon 



1, Leaves subchartaceous, elliptic-lanceolate, 6-13 cm long, 2.5-4.5 cm broad; base 



acute, apex gradually acuminate, plane. 1. Thysanostemon pakaraimae. 



1. Leaves subcoriaceous, elliptic-oblong to oblong, 10-14 cm long, 4-6 cm broad, obtuse 



at the base, apex abruptly conduplicate. 2. Thysanostemon fanshawei. 



1. Thysanostemon pakaraimae Maguire, sp. nov. Fig. 62. 



Arbor parva, ramulis tenuibus, laevibus, castaneis, internodiis vulgo 1-2 cm 

 longis; foliis oppositis vel suboppositis, petiolis tenuibus 8-10 mm longis, plus 

 minusve anguste quadrialatis, transverse tessulatulis vel aliquando rimosis, 

 laminis elliptico-lanceolatis vel oblanceolatis, vulgo 8 cm longis, 2.0-3.5 cm latis, 

 firme chartaceis, paucipunctatis, basi acuta, apice acuminato, costa subprominenti, 

 venis lateralibus prominulis, parallelis, adscendentibus ad 10° angulatas, canal- 

 ibus laticiferis evidentur adscendentibus ad 40°-45° angulatos; floribus solitariis, 

 subterminalibus ; pedunculis 2-3 cm longis, aliquantum clavatis, laevibus, 

 ebracteatis; sepalis 5, cyclicis quincuncialibus, ovato- vel obovato-orbicularibus, 

 5-7 mm longis, 5-10 mm latis ; petalis sepalis oppositis, 5, lineari-oblongis, 3.5-4.0 

 cm longis, 1.0-1.4 cm latis, dextrorse imbricatis, carnosulis, rubritinctis, ad basim 

 gynobasis affixis, apice rotundato, cucullato; staminibus 20-25 in quinque 

 phalangibus aggregatis, quisque 4-5 staminibus instructa; filamentis ex toto in 

 ligulo connatis, solum antheris libris, ligulis planis ca. 2 cm longis, 3 mm latis; 

 antheris extrorsis, apice incurvato, linearibus, 2-locularibus, apice incurvato, 

 connectivo rotundato, filamentis ex toto lateraliter connatis, ligulis 2.0-2.5 cm 

 longis, 2.0-2.5 mm latis, planis; gynobasi ca. 8 mm longa; pistillis oblongo- 

 lanceolatis, ovario 5-loculari, ovulis pluribus in loculo quoque, axillaribus, medio 

 affixis, stylo non conspicue differenti, ramulis ca. 1 mm longis recurvatis; 

 fructibus et seminibus non visis. 



Type. Small tree with slender branches, latex pale, scanty, flowers coralline, 

 hardly opening in anthesis ; infrequent in woodland dominated by Dicymbe spp., 

 head of Kopinang Falls, alt. 925 m, Potaro River-Essequibo River drainage, 

 Pakaraima Mts., British Guiana, 31 Aug 1961, Bassett Maguire, Celia K. Maguire 

 & G. Wilson-Browne 46026 (holotype NY). Several small trees were noted at 

 the type station. 



