Monographs Details: Rogersonanthus tepuiensis (Gleason) Maguire & B.M.Boom
Authority: Maguire, Bassett. 1989. The Botany of the Guayana Highland- Part XIII. Mem. New York Bot. Gard. XIII: 1-127.
Family:Gentianaceae
Description:Distribution and Ecology - K n o w n from elfin or open forest at upper altitudes on the massifs of Chimanta, Auyan-tepui, Ptari-tepui, and Guaiquinima, Bolivar, Venezuela. A single sterile specimen, Tate 860 from Mt. Duida, Amazonas, Venezuela, is doubtfully referred here.

Discussion:

Calolisianthus tepuiensis Gleason, Brittonia 3: 188- 189. 1939. Type. Auyan-tepui, 1800 m, Dec 1937, G. H. H. Tate 1361 (NY).

Macrocarpaea tepuiensis (Gleason) Steyermark, Fieldiana Bot. 28:498. 1953.

Macrocarpaea cerronis Ewan, Contr. U.S. Natl. Herb. 29: 223. pl. 2. 1948. Type. Venezuela. Bolivar: Sororopan- tepui, 13 Nov 1944, J. A. Steyermark 60058 (F, US).

Macrocarpaea salicifolia Ewan, Contr. U.S. Natl. Herb. 29: 224. pl. 3. 1948. Type. Venezuela. Bolivar: Ptaritepui (Sororopan), 15-17 Nov 1944, /. A. Steyermark 60279 (F, US).

Rogersonanthus tepuiensis, of the interior mesas of the Gran Sabana, is closely related to R. quelchii ofthe Roraima-Ilu-tepui chain along the Guyana frontier. Perhaps isolation prevents a free genetic interchange which might otherwise obliterate the rather tenuous distinction between them. Macrocarpaea cerronis and M . salicifolia, based on leaf form, come well within the morphologic and areal range of Rogersonanthus tepuiensis. Rogersonanthus tepuiensis is very closely related to R. arboreus of Trinidad.

Specimens examined. VENEZUELA, bolivar: Auyan- tepui. 1800 m, Dec 1937, G. H. H. Tate 1361 (holotype NY); arbusto de 3 m, flores de color amarillo verdoso, cumbre, 2500 m, Jan 1949, Cardona 2679 (NY); arbusto de 2 m, flores verdes, crece arriba en el plato, 2300 m, Apr 1956, Vareschi & Foldats 4880 (NY, VEN); shrub 2-3 m, cumbre, largo del Rio Churun, 1690 m, 2 May 1964, Steyermark 93234 (NY, VEN); stems 2.5 m, 11 May 1964, Steyermark 93657 (NY, VEN); stems 2.5 m, corolla green, cumbre del brazo noroeste, entre Rio Lomita Camp y Drizzly Camp, 1850 m, 11 May 1964, Steyermark 93657 (NY); unbranching erect stems 3 m, corolla green, 2050-2300 m, 15 May 1964, Steyermark 93975 (NY, VEN). Ptaritepui. Shrub 1-3 m, flowers green, occasional, cumbre (Sororopan), 1800 m, 17 Dec 1952, Maguire & Wurdack 33946 (NY, US, VEN); virgate tree 8 m, flowers green, occasional woodland slopes (Sororopan), 1600 m, 17 Dec 1952, Maguire & Wurdack 33858 (NY, US, VEN). Chimanta Massif Shrub 1 m, upper cumbre Churi-tepui, 2300-2350 m, Wurdack 34294 (NY, US); shrub 8 ft, Bonnetia forests, summit Abacapa-tepui, 2100-2300 m, 13 Apr 1953, Steyermark 74962 (NY, VEN); simple-stemmed plant with erect stems 20-25 feet tall, calyx deep green with carinate lobes, corolla olive-green, 3.5 cm long, tube 2.2 cm broad, lobe 1 cm long, 1.5 cm broad, elfin forest, Apacara-tepui, 2000 m, 19 Jun 1953, Steyermark 75751 (NY, VEN); stems solitary, erect, middle Rio Tirica Falls, 1900 m, 5 Feb 1955, Steyermark & Wurdack 507 (NY, VEN); sin^estemmed shrub 3 m, rare in open forest, Rio Tirica head, 2100-2200 m, 12 Feb 1955, Steyermark& Wurdack 813 (NY, US, VEN). Cerro Guaiquinima. Rim and savannas. West Escarpment, 1800 m, 30 Dec 1951, Maguire 32831A (NY, VEN); shmb 4 m, flowers green, thickets below escarpment at 1400-1700 m, 31 Dec \95\, Maguire 32857 (F, G H , K, N Y , US, VEN); virgate shrub 3 m, in dense "moss" woodland quebrada, North Valley, 1600-1700 m, 4 Jan \952, Maguire 32977 (NY, unicate).