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2 September 2008 A Distinctive New Species of Ouratea (Ochnaceae) from the Jalapão Region, Tocantins, Brazil
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Ouratea acicularis R. Chacon & K. Yamamoto (Ochnaceae), a new species from the recently created Estação Ecológica Serra Geral do Tocantins, Jalapão region, Brazil, is described. Ouratea acicularis appears to be most closely 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 unique in the 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 fibers and sclereids above the collateral vascular bundles, and in the predominantly 2-layered chlorenchyma. 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.

Kikyo Yamamoto, Roberta Gomes Chacon, Carolyn Proença, Taciana B. Cavalcanti, and Dalva Graciano-Ribeiro "A Distinctive New Species of Ouratea (Ochnaceae) from the Jalapão Region, Tocantins, Brazil," Novon: A Journal for Botanical Nomenclature 18(3), 397-404, (2 September 2008).
Published: 2 September 2008

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