Myrcia glaucocarpa

Parra-O, Carlos, 2021, Thirteen new species, new records, and a new combination on Colombian Myrtaceae, Phytotaxa 497 (3), pp. 175-210 : 194-196

9. Myrcia glaucocarpa C. Parra-O., sp. nov.

Type:— COLOMBIA. Amazonas: Araracuara , “río Caquetá, Villazul”, 0°39’S, 72°08’W, 25 September 1992 (fr.), A. Duque & A. Posada 4065 (holotype COAH!). Figure 11 .

Diagnosis:—This species is most similar to Myrcia neoobscura E. Lucas & C. E. Wilson (in Lucas et al. 2016: 680), from which it is distinguished by having the midvein of leaf blade glabrous below (versus strigose in M. neoobscura ), glaucous fruits (vs. blackish), and 5–6 calyx lobes (vs. 4 in M. neoobscura ).

Description:—Shrub or tree, 1.3–6 m tall; hairs when present 0.1–0.7 mm, simple, straight to curled, drying light brownish to golden brownish; young branches teretes, light brown, glabrous to sparsely puberulous; old branches not seen. Leaf blades oblong or ovate to narrowly ovate, 15–21 × 3.5–6.7 cm, coriaceous, discolorous, the upper surface glabrous, with impressed blackish glandular dots, the lower surface glabrous, with impressed blackish glandular dots; apex acute to shortly acuminate, the acumen 7–9 mm; base cuneate, sometimes obtuse; margin entire; midvein convex and glabrous above, convex and glabrous below; lateral veins 18–24 pairs, convex and glabrous above, convex and glabrous below, marginal veins 2, the innermost 1.5–3.5 mm from the margin, the outermost 0.2–0.5 mm from the margin; petioles 0.8–1 cm long, black when dry, rugose, generally glabrous, sometimes slightly puberulous, moderately canaliculate adaxially. Inflorescences mostly axillary, sometimes subterminal, paniculate, 2.2–4.5 cm long, flowers per panicle unknown, axes compressed, moderate to densely pubescent, vinaceous when dry; peduncles 7–21 × 1–1.5 mm; bracts not seen; bracteoles 1–2, axillary at base of hypanthium, ovate, 1–2 × 0.8–1 mm, slight to moderately pubescent, deciduous after anthesis; flower buds and open flowers not seen. Fruits globose, exocarp glaucous when dry, 0.7–1 cm in diameter, glabrous, sessile, calyx lobes persistent in fruit 5–6, irregular in shape and size, ovate to broadly ovate, depressed ovate or oblong, 0.7–1.2 × 0.5–1 mm, coriaceous, scarcely to densely pubescent outside, generally glabrous, sometimes scarcely pubescent inside, apex obtuse or subobtuse, sometimes truncate, remnant staminal ring on fruit circular, 1.4–1.7 mm, glabrous; seed 1, globose, sometimes slightly reniform, 7.5–8 × 6.5 mm, seed coat smooth and somewhat lustrous, with minute orangish glands; embryo myrcioid, with minute blackish glands.

Distribution, habitat and phenology:— Myrcia glaucocarpa grows in seasonal flooded Amazonian forests in Amazonas Department between 200–250 m elev.; this species seems to be endemic to Colombia. Myrcia glaucocarpa has been collected with fruits in September.

Conservation:—Although Myrcia glaucocarpa is known from three different localities in the Amazonas department in Colombia, the Amazonian region is still undersampled and it is difficult to evaluate its conservation status; at the moment, I assess it conservation status as Data Deficient, or DD, following IUCN Red List criteria ( IUCN 2019).

Etymology:—The specific epithet of the new species refers to its glaucous fruits, an uncommon character among species of Myrcia .

Affinities:— Myrcia glaucocarpa is apparently related to M. neoobscura from Brazil, and both species can be differentiated by the characters mentioned in the diagnosis. Calyx remnants in some fruits of Myrcia glaucocarpa have 5–6 irregular lobes, but such lobe numbers are not constant in all fruits of the holotype; in some fruits there seems to be remnants of only four lobes, but it is difficult to be sure due to the poor shape of the remnants. Due to its irregular calyx lobes, it is possible that Myrcia glaucocarpa is related to the species formerly assigned to genus Marlierea ; such species are placed today into three different monophyletic clades within Myrcia ( Lucas et al. 2011) . Flowering specimens are in need to establish Myrcia glaucocarpa affinities within Myrcia .

Myrcia glaucocarpa fruits are covered with a glaucous layer that cracks in small patches ( Fig. 11 D ); the nature of this layer is not known yet, but fungus or another organism growing on the surface of the fruit are discarded. All cited paratypes of Myrcia glaucocarpa do not have flowers or fruits, but they present globose galls ( Figure 11 B ) that are similar in shape to the holotype’s fruits.

The innermost marginal vein of the holotype of Myrcia glaucocarpa is less arched than the same structure on the paratypes cited here, but I consider that this minor difference is part of the existing variation among this species .

Paratypes:— COLOMBIA. Amazonas: Leticia, Parque Nacional Natural Amacayacu , sector Lorena , 03°04’06.2’’S, 69°59’43.2’’W, 70-100 m, 22 November 2019, J . Acosta, M . Ríos, W . Rodríguez, L . Torres & C . Vriesendorp 1190 ( COAH!); Tarapacá , río Putumayo, 2°34’S, 70°13’W, 200–250 m, 18 March 1999, D. Cárdenas, R . López, C . Marín, C . Ruiz & Y . Martínez 11497 ( COAH!); ibidem, 18 March 1999, C . Marín, D. Cárdenas, R . López, C . Ruiz & Y . Martínez 1786 ( COAH!) .

Figures

FIGURE 11. Myrcia glaucocarpa. (A) fruiting branch, (B) galls, (C) fruit, (D) surface of fruit, (E) upper view of fruit with remnants of the calyx lobes, (F) embryo. A, C–F from the holotype, B from Marín et al. 1786. Scale bar for B and C = 5 mm, scale bar for D and E = 1 mm, scale bar for F = 2 mm.