Mouriri oligantha Pilg.

  • Authority

    Morley, Thomas. 1976. Melastomataceae tribe Memecyleae. Fl. Neotrop. Monogr. 15: 1-295. (Published by NYBG Press)

  • Family

    Melastomataceae

  • Scientific Name

    Mouriri oligantha Pilg.

  • Type

    Type. E. Ule 5083 (lectotype, HBG; isotypes, F-frag., G, K, L, MG). Brazil: Amazonas: Bom Fim, Rio Juruá. In flower, Nov 1900.

  • Description

    Description - Glabrous shrub or tree to 20 m high with a trunk to 20 cm or more in diam; young twigs terete; bark whitish (French Guiana); wood very hard. Petioles 2.0-5.0 mm long; blades 6.0-12.0 cm long, 2.4-6.0 cm wide, 1.7-2.9 (-3.1) times as long as wide, elliptic to ovate-elliptic or seldom ovate, acuminate or abruptly so at the apex, sometimes nearly caudate, acute with included angle of 45-90° at base or attenuate or abruptly so, midrib grooved above, rounded below; lateral nerves not visible or obscurely so when dry. Stomatal crypts none; hypodermis present, one cell thick; mucilage walls none; free stone cells present along the midrib to the leaf tip; terminal sclereids stellate, the central body 2-5(-7) times as long as wide, often branching, with few to abundant sharp arms, some arms columnar, rarely the whole sclereid so. Flowers 1-3 in the axils or at each side of leafless nodes of twigs up to 2.5 mm thick, 1 per peduncle, the peduncles 1.3-4.8 mm long, with 1-3 internodes; bracts 0.7-1.4 mm long, elliptic-oblong to ovate, rounded to broadly acute, often present at anthesis, the upper ones larger than the lower. True pedicels 2.6-8.0 mm long; calyx including inferior ovary greenish, 4.8-7.0 mm long, turbinate before anthesis; free hypanthium ca 2.0-2.6 mm long; calyx lobes before anthesis truncate and apiculate, 0.2-0.3 mm long, 0.9-1.6 mm wide, or the lobes indistinguishable, 2.1-4.0 mm long when measured from the stamen attachment, the calyx splitting between the lobes at anthesis for a distance of 2.0-3.0 mm, the lateral edges of the lobes curving outward in age. Petals yellow, ovate-oblong, abruptly acuminate at apex, clawed at base, 7.5-12.0 mm long, 3.6-5.3 mm wide, the claw up to 0.8 mm long, 1.0 mm wide. Antesepalous filaments 6.5-7.5 mm long, antepetalous ones 7.5-8.5 mm long; anthers 2.4-4.4 mm long; sporangia 2.1-2.8 mm long, dehiscing by lengthwise slits; gland 1.1-1.9 mm long, 1.2-2.3 mm from apex of anther when measured from center of gland; cauda ca 1.0-1.5 mm long. Ovary 3-4-locular; ovules axile, all at the same level, 9-12 in all; style 13-15 mm long. Fruit green, covered with a sticky substance, depressed globose, ca 24 mm high and 37 mm in diameter when dry, estimated ca 32 mm high and 46 mm in diam when fresh. Seeds 3, 17.1-20.8 mm high, 20.0-23.0 mm wide, 10.7-12.0 mm thick, with a subrectangular polished area at the base of the outer face ca 5.0 mm high and 4.5 mm wide, the remainder of the outer face irregularly grooved or wrinkled.

  • Discussion

    Mouriri oligantha most closely resembles M. pauciflora. In contrast to the latter, M. oligantha has relatively broad leaves, a different anther form, a longer anther gland, a greater number of ovary locules and ovules, and a larger fruit, and probably larger seeds. The leaves of M. oligantha resemble those of M. collocarpa from which the former is easily distinguished in flower by its single flower on the peduncle, its longer calyx lobes and splitting distance, and the lengthwise dehiscence of its anthers.

    The distributional gap between the plants of western Amazonia and those of Amapá, Brazil, and French Guiana suggests either that the gap will be filled by further collections or that further differences will be found between plants of the two regions, perhaps in the fruits and seeds, which will justify their recognition as distinct groups. At present the only differences I find are in anther size and shape. Anthers from the east are 2.4-3.7 mm long, while those from the west are 3.1-4.4 mm long, with slight accompanying differences in form and position of parts. By themselves these are insufficient evidence for the recognition of two taxa. Mature fruits and seeds are known only from Amapá at present.

  • Distribution

    Northern Peru, lower Río Huallaga; Brazil, Amazonas, basins of the Rio Solimões, Rio Juruá, and Rio Madeira, and in Amapá and French Guiana. Moist forest above or below flood level, often near streams, below 200 m elevation.

    French Guiana South America| Peru South America| Amazonas Brazil South America| Rondônia Brazil South America| Amapá Brazil South America|