Miconia palcazuana Michelang. & R.Goldenb., 2018

Michelangeli, Fabián A. & Goldenberg, Renato, 2018, New and noteworthy Melastomataceae from the Yanachaga-Chemillén National Park and surrounding areas in Oxapampa, Pasco, Peru, Phytotaxa 374 (3), pp. 185-210 : 192-195

3. Miconia palcazuana Michelang. & R.Goldenb. sp. nov. ( Figures 4–5 )

Diagnosis:—Differs from Miconia muricata ( Don 1823: 321) Triana (1871: 102) due to its lower stature, leaves that are basally nerved, narrowly oblanceolate to elliptic-lanceolate and with an acute base (vs. plinerved, rounded to elliptic-ovate, and with the base rounded to cordate in M. muricata ). Also differs by the hypanthium trichomes branched with short arms (vs. not branched) and the presence of fewer glands on the base of the anther connective (4–7 per side vs.>10).

Type: — PERU. Pasco: Province of Oxapampa, Dist. Palcazú, Parque Nacional Yanachaga-Chemillén, Sector Paujil , Trocha hacia la parcela Paujil-Ozus , 10°18’16”S 75°16’38”W, 429m, 12 March 2008 (fl), R. Vásquez et al. 33938 (holotype USM!; isotypes: AMAZ, HOXA!, HUT, MO!, NY!) .

Shrubs or treelets up to 4m tall. Young stems terete to slightly flattened and a bit depressed at the internode apices, and terete with age, interpetiolar ridge thin, but prominent, the young stems densely covered with short dendritic, 0.3–0.5 mm long, ca. 0.3 mm diam., erect, eglandular, whitish trichomes, the axis strongly inflated and globose, with very short arms that seem to be caducous, then the trichomes in older stems are globose, rough but armless, and also sparser. Leaves opposite, isophyllous; petiole 10–39 mm long, with the same trichomes as the stems; blade 8–14.5 × 1.8–3 cm, narrowly oblanceolate to elliptic-lanceolate, apex long-acuminate to broadly caudate, base narrowly rounded, margin thinly hyaline and crenulate, chartaceous, acrodromous nerves 3, basal, plus a very thin, submarginal pair running up to the leaf apex, tertiary complete vein pairs 40–50, with a very few intercalating, incomplete, percurrent veins, midvein, secondary and tertiary veins only slightly impressed, and reticulation barely visible on the adaxial surface, midvein, secondary and tertiary veins strongly prominent, and reticulation impressed on the abaxial surface, adaxial surface glabrous, but with a cluster of trichomes similar to the ones on the petiole right where the secondaries meet the midvein, abaxial surface with sparse stellate trichomes 0.1–0.2 mm diam. in young leaves, caducous and sometimes present near the main veins in older flowers, the main veins with the same stellate trichomes but also sometimes with bigger, globose trichomes like the ones on the petioles. Panicles 7–7.5 × 3.5–4 cm long, terminal, pyramidal, multiflorous, with a single axis and 5–6 pairs of erect paraclades, nodes lacking accessory branches, the axis covered with the same indument as the branches; bracts and bracteoles not seen, and probably very early caducous. Flowers sessile or on short pedicel-like constricted bases less than 1 mm long, 5-merous. Hypanthium ca. 4.5–5 × 3.5–4 mm, campanulate, light green to whitish in fresh material, outside densely covered with dendritic trichomes similar to the ones on young stems and inflorescences, inside glabrous; torus with a fringe of trichomes 0.2–0.3 mm long, glandular. Calyx tube 1.2–1.6 mm long, light green to whitish; sepals internal laminae 2.1–2.6 mm long, triangular, the apex broadly acute or rounded, margins sparsely ciliolate; sepals external projections 0.4–0.5 mm long, tuberculate, acute, slightly shorter than the laminae. Petals 7.6–8.3 × 3.5–3.7 mm, elliptic-lanceolate to oblong-elliptic, apex slightly emarginate and asymmetrical, margin entire, glabrous, white. Stamens slightly dimorphic, fuchsia to dark pink or purple; antesepalous with filaments 6–6.4 mm long, moderately covered with glandular trichomes 0.1 mm long, anthers 5–5.3 mm long, linear-oblong, proximally ventrally arched and distally straight or slightly dorsally arched, pore ca. 0.1 mm diam., slightly ventrally inclined, connective barely prolonged below the thecae, ventrally slightly projected into two narrow, short, rounded auricles, these covered with pedicellate glands 0.1–0.25 mm long; antepetalous with filaments 5.4–5.8 mm long, moderately covered with glandular trichomes ca. 0.1 mm long, anthers 4.3–4.5 mm long, linear-oblong, ventrally arched, pore ca. 0.1 mm diam., slightly ventraly inclined, connective barely prolonged below the thecae, unappendeged, the base with a few pedicellate glands 0.1–0.25 mm long. Ovary 5-locular, 2/3 inferior, the free portion projecting ca. 1mm, terete, apex glabrous; style 12–14 mm long, sigmoidal, moderately covered with glandular trichomes ca. 0.1 mm long, stigma capitate. Mature fruits and seeds not seen.

Paraypes:— PERU. Pasco: Provice of Oxapampa, Dist. Palcazú, Parque Nacional Yanachaga-Chemillén , sector Paujil , margen izquierda del Río Iscozacín ; sobre suelo arenoso en zona innundada, 350 m, 16 July 2017 (fl buds), F. A. Michelangeli & R. Goldenberg 2840 ( HOXA!, NY!, USM!) ; 399 m, 10°19’26”S, 75°15’49”W, 18 September 2014, Vásquez et al. 39095 ( HOXA!, MO!, USM!) ; borde del Río Iscozacín, 10°11’32”S, 75°09’37”W, 330m, 27 January 2007 (fl), R. Vásquez et al. 31690 ( HOXA!, MO!) ; Estación Biológica Paujil, camino hacia el Chiflón, 365m, 10°18’46”S 75°15’44”W, 15 March 2009 (fl), R. Vásquez et al. 35629 ( HOXA!, HUT; MO!, NY!, USM!) ; Estación Biólogica Paujil, colpa Lobo, 405 m, 10°21’32”S 75°14’48”W, 17 March 2011 (fl), R. Vásquez & C. Mateo 37290 ( HOXA!, MO!, USM, NY!) ; orillas de la quebrada “El Venado”, 1274 m [sic], 10°20’46”S 75°15’09”W, 11 March 2015 (fl buds), 11 March 2015, V. Zuñiga 99 ( HOXA!, MO) .

Distribution, ecology, and phenology:— Miconia palcazuana grows along the Iscozacín River and its tributaries at elevations of 300–400 m (the elevation of 1274 m given in the Zuñiga collection is surely mistaken). It is found in sandy areas that are prone to flooding during the rainy season ( Figure 6 ). Flowering material has been collected in March and September, and flower buds in July.

Conservation Status:— Miconia palcazuana has an EOO of 20.78 km 2 and an AOO of 20 km 2, although given its restrictive habitat along river banks, the effective area is much smaller. Half of the collections are known from inside the National Park and the other half outside the park, with some of these within the Yanesha Comunal Reserve. Until we can ascertain the impact of human activities along the Iscozacín River we recommend that this species is considered as Data Deficient ( IUCN 2001; IUCN Standards and Petitions Subcommittee 2017).

Etymology: —The specific epithet refers to the district of Palcazú of the Province of Oxapampa where this species is found.

Comments: —The leaves, flowers and pubescence of M. palcazuana most closely resemble those of M. muricata , a species also found in Central Peru, but that grows at higher elevations (800–1300 m), and it is not associated with flooded vegetation. Both species have leaves with the leaf margins crenate to denticulate, the hypanthium covered with trichomes, and the internal surface of the calyx pilose. However, M. muricata has much larger and broader leaves (11–33 × 10–21 cm vs. 8–14.5 × 1.8–3 cm), that are rounded to elliptic-ovate (vs. narrowly oblanceolate to elliptic-lanceolate) and have a rounded to cordate base and plinerved (vs. acute bases and basally nerved in M. palcazuana ). Additionally, the surface of the hypanthium is more verrucose and has trichomes that lack arms in M. muricata .

It may be pertinent to note that Macbride (1941) considered the possibility of Miconia muricata and M. glandulifera Cogniaux (1891: 951) being the same species, and Wurdack (1972) initially agreed with this assessment. However, close inspection of the venation and trichomes of both types, as well as flower/fruit size shows that these are indeed distinct species (Wurdack 1981). Miconia muricata has now been collected several times in flower in the Tunquí- Huampal sector of the Yanachaga-Chemillén National Park and these collections confirm that the species is in fact distinct from M. glandulifera . However, these specimens also show that M. rosea Gleason (1941: 247) may be a synonym of M. muricata and a detailed evaluation of these two species in Bolivia and Peru is needed.

Figures

FIGURE 4. Miconia palcazuana. A. Fertile branch. B. Flower bud.C. Petal, adaxial view. D. Flower, longitudinal section, petals removed. E. Stamens, from left to right, antepetalous—ventral view, antepetalous—dorsal view, antepetalous—lateral view, antesepalous—lateral view, antesepalous—dorsal view, antesepalous—ventral view.F. Longitudinal (left) and transversal (right) sections of the hypanthium plus ovary. A. Vásquez 35629 (NY); B–F. Vásquez 33938 (NY).

FIGURE 5. Photos of Miconia palcazuana in the field. A. Leaf, abaxial surface. B. Internode and petiole bases. C. Inflorescence before anthesis. D. Flower buds. All from Michelangeli 2840.

FIGURE 6. Distribution of Miconia palcazuana and Miconia yanachagaensis.