A distinctive new species of Ouratea (Ochnaceae) from the Jalapao Region, Tocantins, Brazil

Ouratea acicularis R. Chacon & K. Yamamoto (Ochnaceae), a new species from the recently created Estacao Ecologica serra Geral do Tocantins, jalapao region, Brazil, is described. Ouratea acicularis appears to be most closly allied to O. oleifolia (A. Saint- Hilaire) Engler. Both species share a pubescent indumentum on the young branches, leaf surfaces, inflorescence axes, and outer surface of the flower buds, as well as revolute leaves and acute flower buds. Ouratea acicularis is uinque inthe genus in its aciculate leaf blade, at least 4 times narrower than in O. oleifolia, with a strongly revolute margin that conceals the abaxial leaf surface except for the midrib, as well as its inconspicuous secondary venation and narrower flower buds. Anatomically, O. acicularis differs from other previously studied species of Ouratea Aublet in that the cells of the adaxial epidermis have an hourglass-shaped lumen, pluricellular forked hairs fused at the base, an unusually large cap of fivers and sclereids above the collateral vascular bundles, and in the predominantly 2-layered chlorechyma. the stems of O. acicularis are noteworthy for the conspicuous secretory cavities of the cortex and secondary xylem, in which fibers and vessel members predominate.18339740