Mahechadendron Ariza-Cortes, Cortes-Ballen & Fern. Alonso 2022, gen. nov

Mahechadendron Ariza-Cortés, Cortés-Ballén & Fern.Alonso, gen. nov. (Figures 1–5). Type species:— Mahechadendron puntecascarillo Ariza-Cortés, Cortés-Ballén & Fern.Alonso Diagnosis:— Mahechadendron differs from other Vochysiaceae genera by the following combination of characters: axillary inflorescences in compound dichasia, compact, only developed laterally, with numerous flowers (16–30); flowers with the fourth sepal basally sacciform, villous-lanose inside, sessile, elliptic and villous petal, stamen with a villous-lanose filament, without staminodes, ovary with two ovules per locule; capsular fruit with exocarp fused to endocarp even at maturity, not brittle, with a thick and persistent central column; one seed per locule, unilaterally winged. Description:— Trees, branchlets subopposite, decussate.Axillary cataphylls at the insertion of terminal branchlets, perulate buds prominent. Stipules minute, caducous. Leaves simple, opposite, distichous, caducous; lamina pinnately veined, villous domatia at the base of basal veins in the lower surface. Inflorescences compound dichasia, axillary, congested, main axis minute, many-flowered. Flowers asymmetrical. Calyx with quincuncial prefloration (aestivation), gamosepalous, with cup-shaped base, forming an angle of 40–60 with the pedicel, five unequal sepals, sepal 4 covering the inner whorls, base saccate, revolute in anthesis, inner surface with white villous-lanose indumentum, sepals 1 and 2 slightly unequal in size, sepals 3 and 5 lightly unequal in size, ovate, inner surface with villous-lanose indumentum; corolla with one petal inserted between sepals 3 and 5 (or slightly offset toward sepal 5), white, margin revolute in anthesis, inner surface with villous-lanose indumentum; androecium and gynoecium maturing apparently at the same time; androecium of one stamen placed offset towards sepal 3 or 5, filament with villous-lanose indumentum, anther bilocular, introrse, longitudinally dehiscent; gynoecium with superior ovary, trilocular, with white villous-lanose indumentum, placentation axile, ovules 2 per locule, style cylindrical, stigma subcapitate. Fruit a capsule, trilocular, loculicidal, trivalvous, exocarp soft, slightly tuberculate, glabrous, central column thick, persistent, and shorter than valves. Seed 1 per locule, unilaterally winged, phanerocotylar. Etymology:—The first part of the name of this genus is dedicated to Gilberto Emilio Mahecha Vega (1942–2021), a notable Colombian Botanist, expert in dendrology, who founded the Herbarium UDBC. He was a professor of Botany and Dendrology at the Universidad Distrital Francisco José Caldas in Bogotá and trained generations of Forest Engineer students for more than two decades. Additionally, he is one of the most prolific collectors of Colombian trees and collected the Puntecascarillo for the first time in the ‘60s. The second part, “dendron” is the Greek word for tree and relates to the arborescent habit.
Published as part of Ariza-Cortés, William, Cortés-B, Rocio & Fernández-Alonso, José Luis, 2022, Mahechadendron puntecascarillo (Vochysiaceae), a new genus and forest tree species from Colombia, pp. 89-112 in Phytotaxa 541 (2) on page 93, DOI: 10.11646/phytotaxa.541.2.1, http://zenodo.org/record/6388623