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Family:

Melastomataceae (Magnoliophyta)

Primary Citation:

Phytologia 19(3): 193. 1969

Accepted Name:

This name is currently accepted.

Description:

Description Author and Date: Fabian A. Michelangeli, January 2010, based on Michelangeli, F. A. (2005). Tococa (Melastomataceae). Flora Neotropica Monographs 98: 1-114.

Type: Venezuela. Amazonas: in forests at San Carlos de Río Negro, OCT, Spruce 3130 (holotype K; isotypes BM, NY, P-2).

Description: Shrub, to 0.2-1.2 (-5) m tall. Stems with a mix of caducous lepidote trichomes and glandular setae 1.5 mm long, the nodes glabrous. Petioles 0.3-1.2 (-2.5) cm long, glandular setose. Leaves anisophyllous, oblong-elliptic to round, the larger ones 4-9 (-11) x 3-4.5 (-5) cm, the smaller 2-7 x 1-3 cm, apex broadly obtuse to round, base acute to round or sub-cordate, adaxial surface with glandular setae up to 8 mm long, abaxial surface with a mix of short lepidote hairs and long glandular setae, up to 6 mm long, light green, with 2-3 pairs of secondary veins, plinervate, occasionally basally nervate in leaves without domatia, the margin entire to ciliate-serrulate; domatia present in some of the leaves, but not all, 1/2 to completely immersed in the leaf blade, scrotiform, (1.0-) 2.0-4.0 x (1.0-) 1.5-3.0 cm with glandular setae up to 15 mm long. Inflorescence a cyme, terminal but quickly becoming axillary by overgrowth of the lateral meristem, with 3-6 flowers, 0.5-3 cm long, the axis green, terete, densely stellate pubescent. Flowers on pedicels 2-3 mm long, flared at the apex, subtended by persistent bracts, subulate, 1-2.5 x 0.2 mm; hypanthium broadly conical, 3-3.5 (-4.0) mm long, sparsely glandular setose, with a few caducous stellate trichomes and sessile glands; sepals flattened, 1.5 mm long, connate at the base 0.8 to 1.0 mm, calyx teeth projecting downwards along the hypanthium and laterally compressed, forming "wings" that project perpendicular from the hypanthium 1.0-1.2 mm, glandular setose at the margins; the ring inside the torus glabrous. Petals 5, very rarely 4 obovate to oblong, 10.5-13.0 (-14.5) x 4.5-6.5 mm, base truncate to obtuse, emarginate, smooth to sparsely granulosus, glabrous, bright red or pink. Stamens all of the same size, the filaments 5.5-6.0 mm long, glabrous; anthers yellow; the connective with a dorsal-basal blunt tooth; thecae 3.0-3.5 mm long, opening by a dorsally inclined pore. Ovary 3-locular, completely inferior, the apex with sparse sessile clavate glands; style glabrous, 6-7 (-8.5) mm long; stigma truncate to slightly funneliform. Fruits globose, 3.5-4.5 mm long, black, glabrous to sparsely glandular setose. The seeds not evident through the pericarp, truncate-obovate, 0.8-1.3 mm long, without capitate trichomes in the raphal area, without sculpturing, anticlinal walls straight, periclinal walls flat, boundaries between periclinal walls raised. Chromosome number n= unknown.

Habitat and Distribution: In S Colombia, Venezuela and N Brazil. Endemic to the upper portion of the Río Negro basin. Growing in savannas and forests over white sandy soil (Bana), from 60 to 150 m.

Phenology: Flowering year round.

Ecology: The anthers of T. rotundifolia are heavily preyed upon by pollen robbers such as Trigona bees (see Renner 1983). This phenomenon seems to occur more often in this species, than in other sympatric species of Tococa.

Taxonomy and Systematics: Tococa rotundifolia is related to T. macrosperma with which it shares the highly developed pubescence of leaf blades and domatia surfaced, pseudo axillary inflorescences, red petals, and many aspects of seed morphology. However, T. rotundifolia can be distinguished from T. macrosperma by the winged calyx, and the shape and size of the leaves. This species was originally described as Microphysca by Triana (1871), and was transferred into Tococa by Wurdack (1969), after it had been left in nomenclatural limbo by the transfer by Macbride (1941) of the type species of Microphysca into Tococa. The description of Microphysca rotundifolia includes a note at the bottom as “Myrmidone rotundifolia, Spruce mss” (Triana, 1871). Triana cited Spruce’s notes in a number of other descriptions (effectively causing those species to have Spruce ex Triana as their authorities). It is possible that he did not base his description of Microphysca rotundifolia on Spruce’s manuscript, or that he decided to exclude Spruce’s name, since he was giving the species a different name (Microphysca instead of Myrmidone). Therefore, it is not clear if Triana based his description on Spruce’s manuscript and whether the basionym authorities should be Spruce ex Triana. Since there is no obvious solution to this problem, I have chosen to leave Triana as the sole authority of the basionym, following traditional usage. The type specimen of T. rotundifolia is annotated as coming from San Carlos de Río Negro, in northern Brazil, but this locality is actually in Venezuela. Tococa rotundifolia is locally abundant at San Carlos, where Spruce spent considerable time during his trip, and it surely is the type locality for this species. Tococa rotundifolia has a very narrow distribution, both geographically and ecologically, but where it occurs it is locally abundant.

Flora and Monograph Treatment(s):

Tococa rotundifolia (Triana) Wurdack: [Article] Michelangeli, Fabián A. 2005. (Melastomataceae). Fl. Neotrop. Monogr. 98: 1-114.