1963] 



BOTANY OF THE GUAYANA HIGHLANDS PART V 



129 



M. intermedia seems to be most closely related to M. ptaritepuiana, which 

 shares a similar androecial insertion. But this latter species, although occupying 

 comparable ecological habitats, is easily recognized by its smaller, thinner leaves, 

 smaller flowers and slender branchlets. 



Distribution. BRITISH GUIANA: Mt. Ayanganna, Pakaraima Mts., alt. 

 1400-1500 m, Tillett, Tillett & Boyan 45094. VENEZUELA : Mt. Roraima, im 

 Thurn 337 (holotype K) ; Vie 8663 (K, photo NY) ; Serra do Sol, Maguire & 

 Maguire 40445, 40383; Ilu-tepui, Maguire 33366, 33491, 33574. 



7. Moronobea ptaritepuiana Steyermark, Fieldiana Bot. 28 : 395. 1952. 



Key to the Subspecies of Moronobea ptaritepuiana 



1. Blades dark green, 3-5 cm long, 1.5-2.5 cm broad. subsp. ptaritepuiana. 



1. Blades pale green, 5-8 em long, 2.0-3.5 cm broad. subsp. neblinensis. 



Moronobea ptaritepuiana Steyermark, subsp. ptaritepuiana 



Type. Tree 50-60 ft tall, alt. 1585-1600 m, Ptari-tepui, Edo. Bolivar, Ven- 

 ezuela, J. A. Steyermark 59985 (F, NY). 



Distribution. Apparently confined to high altitudes of the sandstone mesas 

 of the Gran Sabana, Bolivar, Venezuela: Auyan-tepui, alt. 1600 m, Cardona 2625 

 (NY); Chimanta-tepui, alt. 1700 m, Steyermark 75689 (NY). Forma rosea 

 Steyerm. has been distinguished by its rose-colored petals. Type. Cerrao-tepui 

 (Ptari-tepui), Steyermark 60892 (F, NY). 



Moronobea ptaritepuiana Steyermark subsp. neblinensis Maguire, subsp. nov. 



Arbor parva ; f oliis maioribus, laminis 5-8 cm longis, 2.0-3.5 cm latis, pallidis, 

 glandulo-punctatis, saepe item rubripunctatis, floribus maioribus, petalis albidis 

 4-5 cm longis ; phalangis 3-4-antherifes. 



Type. Tree 5 m high, petals white, young fruit greenish-white, occasional, 

 slopes Canon Grande below Cumbre Camp, alt. 1800 m, Cerro de la Neblina, 

 Amazonas, Venezuela, 14 Dec 1957, Bassett Maguire, J. J. Wurdack & Celia K. 

 Maguire 42466 (holotype NY). Paratypes. Cerro Neblina: Maguire, Wurdack & 

 Bunting 37336; Maguire, Wurdack & Maguire 42172. Known only from Neblina. 



As observed in the field, the subsp. neblinensis is considerably smaller than 

 is indicated for the tree of the Gran Sabana. The western race exhibits larger, 

 thinner and conspicuously paler leaves and larger flowers. The number of anthers 

 per phalange has proved to be variable in general for species of Moronobea, and 

 is not here considered significant. Steyermark ascribes 5 per phalange for subsp. 

 ptaritepuiana. As noted above, Ave have observed 3-4 for subsp. neblinensis. 



In addition to numerous minute impressed clear glandular punctae that are 

 characteristic for the species, the leaves of subsp. neblinensis exhibit raised 

 reddish and larger subepidermal pustules of an apparently resinous nature. They 

 are often of irregular size and distribution on the lower leaf surface. These resin- 

 dots are not associated with any fungal pathogen. They may be of natural secre- 

 tion, but the possibility of their being insect induced should not be ruled out. 



3. Lorostemon Ducke, Arch. Inst. Biol. Veg. 1 : 210. 1935. 

 Type species. Lorostemon bombaciflorus Ducke. 



