Miconia humifusa Jan.M.Burke & Michelang., 2014

Cárdenas, Lizeth A., Burke, Janelle M. & Michelangeli, Fabián A., 2014, Five new species of Miconia (Melastomataceae) from the Central Peruvian Andes, Phytotaxa 188 (3), pp. 121-134 : 130-131

Miconia humifusa Jan.M.Burke & Michelang. sp. nov. ( Fig. 5 )

Prostrate shrub with adventitious roots; young stems with brown barbellate trichomes; petioles 1.3–3.3 cm long; lamina 2–3.3 × 1.3–2.3 cm, ovate; flowers 4-merous; ovary 4-locular; style with gland-tipped hairs at base; stigma broadly peltate.

Type:— PERU. Pasco: Prov. Oxapampa, Dist. Huancabamba , Sector Oso Playa ?, trocha a la parcela Oso Playa , 10˚17´58˝ S, 75˚36´35˝ W, 2370–2475 m, 24 June 2006 (fl) , L. Cárdenas & R. Francis 456 (holotype HOXA!, isotypes CUZ!, MO!, USM!) .

Prostrate subshrub with adventitious roots, up to 15 cm tall. Young stems terete, indument glabrous to villous with brown barbellate trichomes, ca 0.4 mm long, nodal line faint. Phyllotaxy opposite, though leaves frequently oriented to 1 side of stem. Leaves isophyllous; petioles 1.3–3.3 cm long, indument glabrous to moderately puberulous with flexuous, barbellate, gland-tipped trichomes; lamina 2–3.3 × 1.3–2.3 cm, ovate, membranaceous, base rounded, apex bluntly acute, margin serrulate, teeth linear and ca. 0.6 mm long, 0.3 to 1 mm apart; 1 pair of secondary veins plus 1 pair of faint marginals, basally nerved, symmetrical, tertiary veins percurrent, arched ca. 80 deg angle from midvein, quaternary veins reticulate, veins slightly impressed on the adaxial surface and raised on the abaxial surface, drying brown to purple; adaxial surface green, indument on the surface glabrous, and hirtellous on the primary and secondary veins, especially along the periphery, the trichomes simple, appressed, 0.3–0.4 mm long; abaxial surface green to dark green (drying purple or yellow), indument on the surface sparse sessile glands <0.05 mm, and glabrous to sparsely setulose on the veins, simple trichomes ca. 0.1 mm long. Inflorescence terminal, simple dichasia of 3 flowers, 1.8–2 cm long; peduncles terete, brown, indument glabrous to sparsely puberulent with barbellate hairs, flowers erect; bracts 4–4.8 × 2.3 cm, ellipsoid, persistent at anthesis, foliaceous, margin ciliate and apex with barbellate trichomes up to 0.3 mm long; bracteoles 2–3.5 × 0.5 cm, oblong to subulate, persistent at anthesis, sparsely ciliate. Flowers with pedicels 1.3–2 mm long, with sessile pigmented glands.. Hypanthia 3.2–3.8 mm long, urceolate, 3.8–4.4 mm wide at the torus, externally covered with sparse gland-tipped trichomes, setulose towards apex, internal surface with sparse sessile glands <0.05 mm. Calyx open in bud; tube 0.4 mm long at anthesis; lobes 0.6–0.8 × 0.5–0.6 mm, deltoid, glabrous, hyaline, appressed to calyx teeth; teeth 0.6–1.1 × 0.5–0.8 mm, deltoid, apex swollen, puberulant with trichomes ca. 0.4 mm long, as hypanthium. Petals 4, 3 × 2.5 mm, suborbicular, erect, white at anthesis (drying brown), sparsely puberulent with gland tipped trichomes on both surfaces, base obtuse, apex retuse, margin entire. Stamens diplostemonous, isomorphic, rigidly erect, radially spreading at anthesis; filaments 3.3–4.2 mm long, up to 1 mm wide, dilated at base, puberulent with gland tipped trichomes, white; anthers 4-locular, connective with small dorsal hump, white, puberulent with gland tipped hairs, thecae 1–1.2 × ca. 1 mm, stout, opening by 2 ventral pores, becoming rimose with age, white at anthesis, later turning brown. Ovary 4-locular, completely inferior; style ca. 4 mm long, up to 8 mm after anthesis, erect, hirsute with gland tipped hairs at base; stigma peltate, 1 mm wide. Berries immature, 4.8–5 × 4.8–5 mm, urceolate, green. Seeds 0.6–0.7 mm long, apiculate, ovoid, the hilum covering 70% of the seed.

Distribution: — Humid montane forest, with parcels of pajonal, 2370–3479 m in the province of Oxapampa, Pasco, Peru

Phenology: — Flowering in June, fruiting in November.

Etymology: — The epithet refers to the prostrate or scrambling habit of this species.

Conservation Status:— Miconia humifusa is only known only from two populations, one inside the Yanachaga Chemillen National Park and a second one just outside, with a total EOO of less than 20 km 2 and thus should be considered as Data Deficient (DD) under IUCN criteria (2001). Based on its restricted distribution and habitat, following IUCN criteria (2001) as implemented in the IUCN guidelines (2011) we recommend that this species is considered Critically Endangered.

Additional specimens examined: PERU: Pasco: Prov. Oxapampa, Dist. Huancabamba, sector Santa Barbara, camino a Huayllar , 10˚21´57˝ S, 75˚39´47˝ W, 3479 m, 29 November 2006 (fr) , Cárdenas et al. 958 ( CUZ!, MO!, NY!) .

Discussion:—The prostrate habit of Miconia humifusa at high elevation, only allies it to two other species: Miconia chionophila Naudin (1850: 236) / Miconia rotundifolia ( Don 1823: 311) Naudin (1850: 235) . Miconia rotundifolia / M. chionophila constitute a species complex (or complex species). Though this species complex is morphologically quite variable in leaf shape and size, the leaf size of M. humifusa (2–3.3 cm long) extends beyond the leaf size range of the aforementioned species. Miconia rotundifolia rarely exceeds 2 cm long, often with a cordate base. The leaf size, combined with the petiole length that is at least as long as the leaf lamina, long internodes and conspicuous production of adventitious roots, allows Miconia humifusa to be differentiated from other Andean prostrate Miconia species. Outside of the Andes, another specimen of prostrate Miconia with leaves exceeding 2 cm long has been collected from the Talamanca mountains of Central America (Davidse 25967, NY), and is determined as M. rotundifolia . Though morphologically quite similar, we hesitate to combine these disparate populations into one species. The Talamanca populations of M. rotundifolia need to be studied in closer detail.

One notable character of Miconia humifusa is the yellow or purple hue of the leaves when dry. The closely-related species, Miconia rotundifolia (see also Melastoma repens nom. herb./ Rhexia repens nom. herb.) has been noted as a source of yellow dye called “ola-ola”, producing a yellow tincture, when combined with Miconia tiri Triana (1871: 127) (see also Tiri tomentosa nom. herb.) and Bocconia frutescens Linneaus (1753: 505) to dye wool (Ruíz annotation on MA sheet; Ruiz 1940).

Figures

FIGURE 5. Miconia humifusa. A. Habit. B. Petal. C. Stamen. D. Longitudinal section of bud, note gland-tipped hairs at base of style and long pedicel. E. Detail of hypanthium (Cardenas 456, MO).