Meriania juan-canoi Posada

Posada-Herrera, Juan Mauricio, Idárraga, Álvaro & Alzate, Fernando, 2020, A new species of Meriania of the Brachycera group (Melastomataceae: Merianieae) with dimorphic stamens, Phytotaxa 442 (3), pp. 225-231 : 226-228

Meriania juan-canoi Posada ‒Herrera, Idárraga & Alzate sp. nov. ( Figs. 1–3 ).

Type: — COLOMBIA. Antioquia, Municipality of La Unión : Mesopotamia, locality El Cardal, 05°53’30’’ N, 75°18’35’’ W, 2450 m, 28 June 2018 (fl, fr), J. S. Murillo Á. Idárraga, F. Alzate, J. Cano & A. Arcila, 103 (holotype HUA!; isotypes COL, FMB) .

Diagnosis: Meriania juan-canoi is characterized by the slightly anisophyllous leaves with rounded or cordate base, suprabasal nerves and conic densely roughened trichomes, dimorphic stamens, antesepalous stamens with the connective appendage with a bifid apex, an apically rounded calyptra that opens irregularly and the ovary completely free from the hypanthium.

Tree 4–5 m tall, highly branched and tree crown with dense foliage, distal quadrangular internodes 4–9 cm long. Indument consisting of conic densely roughened trichomes, these brownish on petioles, veins on the abaxial leaf surface, axes of the inflorescences and hypanthium and reddish on the flower buds and younger parts. Leaves at the same node slightly anisophyllous. Petioles terete, 2–4.2 cm long, ca 1.5 mm diam. Leaf blade rigid and brittle, 6.5–19.2 × 3–11.5 cm, elliptic to broadly elliptic; apex acuminate; base obtuse, occasionally slightly cordate; margin revolute and slightly crenate; with two pairs of suprabasal veins following the midvein, the first pair closest to the middle vein 3–6.7 mm above the base, and 25–40 tertiary veins perpendicular to the middle vein, 2.5–6.5 mm apart along the midrib; dense pubescence in upper surface of young leaves, and glabrous in adults leaves, the trichomes dimorphic, most of them conic, roughened, brown, and also with hyaline sessile glandular trichomes on the abaxial surface of the veins. Inflorescence a terminal dichasial cyme, widely branched, 15–25 cm long, with 28–36 flowers; 2–4 branching nodes in the central axis, quadrangular internodes when dry, inflorescence sessile or with a peduncle 4.5–6.5 cm long; flattened branchlets; basal paraclades 5–15 cm long, with 1–2 branching levels; dichasial branches. Bracts foliaceous, narrowly ovate, apex acuminate or sometimes obtuse, the basal ones 8–10 x 2.5–3.5 cm, the distal ones 5.5– 1.4 cm. Bracteoles deciduous, linear 6–7 mm long. Flowers 5-merous, diplostemonous. Pedicel with the same pubescence of the branches, 0.7–1.7 cm long. Hypanthium campanulate, 1–1.1 x 1.2–1.6 cm; walls 1.1–1.4 mm thick. Calyptra crustaceous when dry, 0.7–1.3 cm long before anthesis, opening irregularly into three or five lobes, rounded apically; external calycine triangular teeth at the base of the calyptra 3–3.9 mm long. Petals obovate, margin entire, 2.8–3 × 2.1–2.6 cm long, glabrous, magenta and light pink in senescence. Stamens 10, dimorphic, arranged on the lower side of the flower, the antepetalous whorl with longer anthers. Antesepalous stamens: filaments ca. 1.7 cm long, ca. 2.0 mm wide near the base and ca. 1 mm wide near the apex, pink, ascendant elbow or filament apex/base of the connective, 0.7 × 0.4 mm, slightly mucronate, white; connective dorsal appendage parallel to the anther, bifid, ca. 2.1 × 1 mm, white with a purple apex; anthers straight, subulate, ca. 1.1 cm long, purple, pore ca. 0.3 x 0.3 mm, dorsally inclined; pedoconnective absent. Antepetalous stamens: filaments 2.3 cm long, ca. 2.0 mm wide near the base and ca. 1 mm wide near the apex, pink, ascendant elbow or filament apex/base of the connective ca. 1.2 × 0.7 mm, subulate, white; connective dorsal, appendage subulate and ca. 4 × 1 mm, white with a purple apex; anther 1.4–1.5 cm long; pore 0.5 x 0.4 mm, dorsally inclined, purple; pedoconnective 1.3 mm long. Ovary completely superior, 6.5–6.7 × 6.3–6.4 mm, ovoid, with 5–6 ribs in cross section, slightly raised in the middle; apex with protruding broad and dull lobes, ca. 1.9 mm long; carpels 5; placenta ovate, 2.1–2.2 × 0.7–0.8 mm. Style columnar-conical, ca. 1.8 cm long, base ca. 3–4 mm diam, curved towards the apex, 1.8–1.9 mm diam, fuchsia. Stigma slightly expanded, ca. 1.6 mm diam, papillose. Fruits a spherical capsule, exposed by a deciduous hypanthium. Seeds linear with an elongated apex, 1.3–1.7 x 0.2–0.3 mm; hilum well-defined and a little darker than the testa.

Phenology:— Specimens in flowers have been collected during March and November and with flowers and fruits during June.

Etymology:— The new species is dedicated to Juan Cano, a Colombian agronomist and enthusiastic naturalist who has devoted great efforts to know and reproduce many of the species of the Andean forests, including this taxon.

Habitat and distribution:— Meriania juan-canoi is endemic from Colombia where it is known only from two localities. The few individuals found for this species have been recorded in the northern part of the Central Cordillera of Colombia, on the plateau east of Antioquia. This species occurs in Andean forests at elevation between 2176 and 2500 m. The two places where collections come from corresponds to highly converted areas with intense agricultural and livestock activity. However, the plants usually grow on the edges of small basins where agricultural activities cannot be carried out, which has favored their persistence.

Conservation status:— Meriania juan-canoi has an extension area (EOO) of 0 km² and an occupation area (AOO) of 8 km ². Due to the intense agricultural activity in the area where this species grows and the small area where it occurs, we recommend a conservation classification of Critical Risk (CR): B1, B2ab (i, ii, iii, iv).

Additional specimens examined (paratypes):— COLOMBIA. Antioquia. Municipality of La Unión, near to Mesopotamia, 2500 m, March 2011 (fl), J. Cano 2 ( MEDEL!), Mesopotamia , locality El Cardal , 05°53’30’’ N, 75°18’35’’ W, 2450 m, 28 June 2018 (fl), Á. Idárraga, F. Alzate, J. Cano, S. Murillo & A. Arcila 6642 ( HUA!, JAUM!) ; Municipality of Sonsón, locality La Aguada , 5°42’36’’ N, 75°13’05’’ W, 2176 m, 12 November 1997 (fl), A. Cogollo, H. Rincon, A. Duque, J. Giraldo & W. Giraldo 11466 ( JAUM!) .

Figures

FIGURE 1. Meriania juan-canoi. A. Terminal branch with inflorescence. B. Flower buds. C. Calyptra opening irregularly. D. Flower at anthesis. E. Longitudinal section of the flower. F. Petal. G. Ovary. H. Longitudinal section of the ovary. I. Antesepalous stamens. J. Antepetalous stamens. K. Fruits. L. Seeds.All drawn from the holotype.

FIGURE 2. Meriania juan-canoi. A. Adaxial surface of the leaf. B. Abaxial surface of the leaf. C. Flower buds. D. Flowers and calyptras. All from J. S. Murillo et al. 103.

FIGURE 3. Geographic distribution of Meriania juan-canoi.