Maguire, Bassett & Wurdack, John J. 1964. The botany of the Guayana Highland--Part V. Mem. New York Bot. Gard. 10: 1-278.
Melastomataceae
Latin Diagnosis - M. pseudocapsulari Wurdack affinis sed floribus paniculatis non secundis calycis dentibus exterioribus anguste triangularibus vix eminentibus. Frutex vel arbor parva 1.5-8 m inflorescentiis exceptis glabra. Folia aequalia vel vix inaequalia; petioli 1.5-5 cm; lamina 10-30 X 4.5-10 cm elliptica vel vix obovato-elliptica apice per 1-1.5 cm subabrupte hebeti-acuminata basi cuneata membranacea fragilis 5-plinervata jugo interiore subalternatim 1-2.5 cm supra basim inserto jugo exteriore attenuato marginali nervis secundariis plerumque 5-10 mm inter se distantibus tertiariis paucis laxissime reticulatis integra. Panicula 6-13 cm longa pyramidata inconspicue caduceque furfuracea ramulis ultimis in dichasiis 2-3-floris interdum congestis; bracteolae 0.3-0.5 mm longae subulatae persistentes ca. 0.8-1 mm infra hypanthium insertae; flores 5-meri ca. 1-1.2 mm pedicellati glabri. Hypanthium (ad torum) 2.5 X 1.5 mm anguste oblongum vix 10-costatum; calycis tubus 0.1 mm altus, lobis interioribus 0.5-0.6 mm longis orbiculari-triangularibus apice rotundatis, dentibus exterioribus 0.2-0.4 mm eminentibus apiculatis. Petala 2 X 0.8 mm obovato-oblonga apice vix oblique emarginata glabra. Stamina in dimensionibus vix dimorphica; filamenta 3.5 vel 2.5 mm; antherarum thecae 2.6 vel 2.3 mm subulatae sub filamenti insertionem ventraliter 0.5-0.6 mm prolongatae et cum connectivo coalitae, connectivo sub thecas non prolongato dorsaliter non appendiculato. Stylus 12.5 X 0.25 mm; stigma truncatum; ovarium 3-loculare 1/8-inferum apice in collum 0.1-0.15 mm longum circum stylum protractum et 5-6 setulis 0.05 mm longis ornatum. Semina 0.5-0.6 mm longa laevia vel inconspicue sparseque tuberculata.
Type. Leaves dark green above, light green beneath, brittle, calyx and corolla white, anthers yellow, frequent in forest below talus along cliffs on N E side of Mt. Ayanganna, upper Mazaruni River, British Guiana, alt. 800-900 m, 1 Aug 1960, Stephen S. Tillett, Carolyn L. Tillett, & Rufus Boyan 44977 (holotype US 2343854). Paratypes. SURINAM. Tafelberg: overhanging East Ridge Gorge, Maguire 24533. BRITISH GUIANA. Mt. Ayanganna: alt. 1070 m, Tillett, Tillett, & Boyan 45130. Karowtipu: alt. 490 m, Tillett, Tillett, dc Boyan 45439. VENEZUELA. Edo. Bolivar. Sororopan-tepui: alt. 1500-1800 m, Steyermark 60177, Maguire & Wurdack 33960. Carrao-tepui: alt. 1400-1600 m, Steyermark 60843.
M. pseudocapsularis has completely secund flowers on pedicels only 0.5 m m long and inner calyx lobes equaling the subulate external teeth; originally known only from Amazonas, the species has also been collected on the slopes of Toronotepui (a part of the Chimanta Massif in Edo. Bolivar) at 1500 m elevation (Steyerm.ark 75490). The foliage of M . tillettii is rather reminiscent of, although much thinner than, that of M. fragrans Cogn. M. fragrans is known from Trinidad, Tobago, British Guiana (Mt. Ayanganna, Tillett, Tillett, & Boyan 45113), and Venezuela (Cerro La Danta, Edo. Bolivar, Steyermark & Nilsson 30,188).
The related species, 31. lateriflora Cogn., continues to accumulate synonyms. M. tessmannii Mgf., from Amazonian Peru, is the same as Amazonian and Guianan material previously referred to M . lateriflora. As would be expected in such a wide-ranging species, there is some variability; Central American and Pacific Colombian collections show calyx teeth 1.5-2 m m long, while Amazonian and most Guianan specimens have teeth only 1 m m long. More extreme are the Kanuku Mountains (British Guiana) collections (A. C. Smith 3571, 3665), with pedicellate lateral flowers in each dichasium, as well as the calyx limb only undulate-rimmed and inconspicuously toothed. Probably subspecific recognition (or perhaps specific in the case of the Kanuku population) will be given to the variants; in any event, Markgraf's name properly falls under the typical subspecies of M . lateriflora.