Mahechadendron puntecascarillo Ariza-Cortés, Cortés-Ballén & Fern.Alonso, 2022

Ariza-Cortés, William, Cortés-B, Rocio & Fernández-Alonso, José Luis, 2022, Mahechadendron puntecascarillo (Vochysiaceae), a new genus and forest tree species from Colombia, Phytotaxa 541 (2), pp. 89-112 : 93-100

Mahechadendron puntecascarillo Ariza-Cortés, Cortés-Ballén & Fern.Alonso , sp. nov. ( Figs. 1–5 ).

Type: — COLOMBIA. Santander: Mun. Cimitarra, Vereda Bonanza , Finca El Jardín . En relictos de bosque sobre colinas disectadas, con pendientes fuertes. Altitud: 200–300 m, 25 March 2019, (fl), W. Ariza-Cortés 8450 (holotype UDBC!; isotypes COL!, CUVC!, FMB!, HUA!, JAUM!, UIS!, UDBC!, UPTC!) . [Inflorescences and wood samples deposited in the UDBC complementary wet collection -Anthoteca-, and in the Xyloteca José Anatolio Lastra, respectively].

Tree, deciduous, (16)20–28(35) m tall, (40)70–120(190) cm in diameter, trunk base canaliculate or with poorly developed rounded fins; trunk reddish-brown (inside the forest) or dark gray (at full sun exposure), white-spotted, slightly canaliculate, rhytidome slightly fissured, with thin plates, living bark thin, cream. Wood dense and heavy, heartwood dark maroon, sapwood cream. Crown small, loose foliage, branchlets subopposite, decussate, exfoliating in thin flakes; terminal branchlets distichous, subopposite, shortly villous in two longitudinal rows becoming glabrescent in older branchlets, axillary cataphylls at the insertion of terminal branchlets, perulate buds prominent, glabrous. Stipules minute (<1 mm long), falling early. Leaves simple, opposite, distichous; petiole slightly canaliculate, strigulose mainly on the upper surface, 1.5–3 mm long, 0.7–1.1 mm in diameter; lamina light green, coriaceous, shiny adaxially, elliptic to narrowly elliptic, 3–11 cm long, 0.6–2.5 cm wide, base attenuate or subcordate, apex acuminate or mucronate, margin entire, slightly revolute, young leaves pubescent with ciliate margin, mature leaves glabrescent; lamina pinnately veined, main vein flat or slightly sulcate adaxially, prominent abaxially, glabrous or hairy from base to the lamina center, secondary veins brochidodromous, 11–21 vein pairs, spaced irregularly, prominulous adaxially, prominent abaxially, about straight, bending toward the margin, often with villous domatia at the base of basal veins in the lower surface, tertiary veins reticulate, quaternary veins open. Inflorescences compound dichasia, congested, axillary, often rising from buds protected by cataphylls; peduncle 1–2 mm long, 0.7–0.8 mm in diameter, secondary and tertiary rachis very short, (8)16–26(30) flowers; bracts ovate to deltoid, margin ciliate, strigose, 0.4–0.5 mm long, 0.45–0.5 mm wide, bracteoles 0–3, at pedicel base, the central larger, 0.3–0.4 mm long, 0.3–0.4 mm wide, partially covering the two smaller lateral ones, 0.2–0.3 mm long, 0.2–0.3 mm wide; pedicels slightly canaliculated, (0.3)0.8– 1.2(1.5) mm, strigose. Flower bud ovoid, base oblique, (0.9)1.4–3(3.3) mm long, (1)1.1–2(2.5) mm wide. Flowers asymmetrical, calyx with quincuncial prefloration (aestivation), gamosepalous, cup-shaped base, five unequal lobes, sepal 4 cream or yellow, covering the inner whorls, base saccate, revolute in anthesis, 2.5–3 mm long (extended), inner surface with villous-lanose indument, hairs long, sinuous, white, glabrescent toward the base, externally strigose; sepals 1 and 2 green, margin whitish, ovate to orbicular, slightly unequal in size, 0.4–0.7 mm long, 0.4–0.6 mm wide, strigose, margin ciliate; sepals 3 and 5 cream to green, margin whitish, ovate, slightly unequal in size, ovate, 0.5–1.2 mm long, 0.6–1 mm wide, externally strigose, inner surface with villous-lanose indumentum; corolla with one petal, white to cream, slightly fleshy, inserted between sepals 3 and 5 (or slightly offset toward sepal 5), sessile, oblongelliptic, margin revolute in anthesis, 2–2.4 mm long, 1–1.7 mm wide, inner surface with villous-lanose indumentum, strigose externally; androecium of one stamen placed offset towards the sepal 3 or 5, 2– 3.2 mm long, filament flattened or elliptic, with white villous-lanose indumentum, base slightly inflated, up to 0.4 mm in diameter, 1.2–2.2 mm long, anther bilocular, oblique, reniform, 0.6–0.9 mm long, 0.7–1 mm wide, introrse, longitudinally dehiscent; gynoecium with superior ovary, ovoid, slightly flattened, 1–1.5 mm long, with white villous-lanose indumentum, trichomes 1.2–2 mm long, trilocular, ovules 2 per locule, style cylindrical, up to 1.6 mm long, stigma terminal, subcapitate. Fruit a capsule, oblong, base and apex acute to slightly round, 2–3 cm long, 0.6–0.9 cm in diameter, trivalvous, dehiscing from apex to base, exocarp soft, slightly tuberculate, glabrous, central column persistent, oblong, trigonous, with acute angles, slightly winged. Seed 1 per locule, 1–2 aborted (1–2 per fruit), linear-oblong, 1.4–2.6 cm long, 0.4–0.7 cm wide, apical wing, glabrous, seed chamber basal, phanerocotylar. Germination epigeal. Seedling, hypocotyl maroon to purple, basally terete, becoming quadrangular toward cotyledon insertion, densely pilose; cotyledons opposite, petiole reddish, flattened to slightly canaliculate adaxially, laminas isophyllous, orbicular, base cordate, margin undulate, reddish, 2–2.9 cm long, 1.2–1.6 cm wide, 3–5 basal veins, reddish, impressed adaxially, prominent abaxially, first true leaves lanceolate, densely pilose, central vein reddish.

Distribution and ecology:— Mahechadendron puntecascarillo has been collected in the middle Valley of the Magdalena River, in the Departments of Santander and Norte de Santander in Colombia ( Fig. 6 ). However, we have seen photographs of individuals in Puerto Berrío (Antioquia), and Puerto Boyacá (Boyacá). It grows on dissected steep hills slopes in tropical moist forest. Some common tree species in these forests are Brachycylix vageleri ( Harms 1925: 291) Cowan (1975: 464) , Virola sebifera Aublet (1775b: 904–905) , Pouteria cuspidata (A. Candolle 1844: 183) Baehni (1942: 231–232) , Brownea santanderensis Quiñones (1995: 19–21) , Swartzia oraria Cowan (1967: 163) , and several species of Eschweilera Martius ex Candolle (1828: 293) . Few seedlings and young individuals were observed close to adults inside the forest but not in open areas.

Phenology:—Flower specimens have been collected from February to April and fruiting collections from April to June.

Suggested conservation status:—The area of occupancy of M. puntecascarillo is close to 80,000 km 2. This species grows in a region with continuous forest degradation, and its highly durable wood is still used intensively for construction ( Fig. 7 ).We consider it meets four of the criteria for the category of Endangered (EN; criteria A2cd; B1a+2a), related to reducing population size and area of occupancy ( IUCN 2012) due to forest loss and fragmentation.

Etymology:—Specific epithet refers to the common name of this species. Spanish prefix “punte” is locally used to forest tree species with highly durable wood, while “cascarillo” means that the cortex fell apart in shells.

Paratypes: — COLOMBIA. Norte de Santander: La Esperanza, límite entre las veredas Morrocoyes y Raiceros, 7.619811°N, 73.375466°W, 202 m, 25 May 2021, D. Sánchez 250 (HUA!). Santander: Cimitarra, vereda Oponcito, Finca La Primavera, árbol aislado en potrero, 100–200 m, 6°25´28” – 73°55´22”, 3 December 2019, L. Carvajal et al. 4086 (UDBC!); Puerto Araujo, árbol aislado en potrero, cerca a la autopista Ruta del Sol, 200 m, 6°29´N – 74°10´W, 20 June 2012 (fr.), W. Ariza-Cortés 3330 (UDBC!); Carare-Opón, June 1969 (fr.), G. Mahecha s.n. (UDBC-11876!); Carare-Opón, 1969, R. Abascal & R. Juyó s.n. (UDBC-3289!); Sabana de Torres, límite entre las veredas Cristales y Payoa Cinco, 7.282009°N, 73.490404°W, 186 m, 11 May 2021 (fr.), J. M. Cárdenas 2206 (HUA!); Vereda San Rafael de Payoa, 7.188020°N, 73.507801°W, 169 m, 5 April 2021, J.F. Hernández 489 (HUA!).

Figures

FIGURE 1. Illustration of Mahechadendron puntecascarillo. A. Terminal branches showing young leaves and inflorescences. B. Leaf, adaxial view. C. Flower at anthesis (lateral view) showing saccate sepal (right) and revolute petal (left), stamen and style in central position. D. Petal with revolute margins (abaxial side). E. Stamen. F. Gynoecium (lateral view). G. Ovary transverse section showing central column, two ovules per locule, and copious villous-woolly indumentum. H. Fruit at the beginning of dehiscence. I. Open fruit showing the three valves in erect-patent position and the thick central column. J. Seed. Illustration by Omar Bernal.

FIGURE 2. Mahechadendron puntecascarillo. A. Habit, tree up to 35 m tall. B. Trunk base, rhytidome, and living bark. C. Distichous leaves on terminal branches. D. Young perulate bud (arrow) on a mature branch. E. Mature leaves (abaxial side). F. Close-up of stipule (arrow) and leaf bases of young branches. G. Close-up of villous domatia at the base of secondary veins, abaxial side. H. Close-up of leaf venation. Photos A, C by Rocio Cortés-B.; B, D–F, H by W. Ariza-Cortés; G. by J.L. Fernández-A.

FIGURE 3.Mahechadendron puntecascarillo.A.Floriferousyoungbranches showing axillaryinflorescences.B.Closeup ofinflorescences showing open flowers and flower buds. C. Branch showing bark exfoliating in thin flakes and cataphylls of former perulate buds. Photos by W. Ariza-Cortés.

FIGURE 4. Mahechadendron puntecascarillo. A. Branch showing two axillary and compact inflorescences.B. Portion of an inflorescence showing an open central flower and two lateral branches. C. Open flower (lateral view). D. Flower longitudinal section showing the revolute petal and stamen (left), pistil (center), and the distally revolute saccate sepal. E, F. Ovary transverse section showing the central column, three locules, and ovules in pairs. Photos B, C, F by W.Ariza-Cortés; A, D, E by J.L. Fernández-A.

FIGURE 5. Mahechadendron puntecascarillo. A. Immature fruits erect on the branch. B. Branch showing mature fruits with different dehiscence degrees. C. Open mature fruits showing valves and central column. D. Close-up of fruit valves, externally slightly tuberculate (left), internally smooth and shiny (right). E. Seeds showing unilateral shiny wings. F. Close-up of a seed. G. Seedlings showing cotyledons and true leaves. Photos A–C, E, G by W.Ariza-Cortés; D, F by J.L. Fernández-A.

FIGURE 6. Distribution map of Mahechadendron puntecascarillo.

FIGURE 7. Mahechadendron puntecascarillo. A. Tree recently cut down. B. Tree stump showing the dark heartwood. C. Sawn timber in the field. Photos by W.Ariza-Cortés.