Meriania rubriflora 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 : 190-192

2. Meriania rubriflora Michelang. & R.Goldenb. sp. nov. ( Figure 3 )

Diagnosis:—Differs from Meriania tetragona ( Cogniaux 1908: 137) Wurdack (1964: 411) due to the petioles lacking protuberances right at the insertion into the leaf blade (vs. petioles with protuberances in M. tetragona ), acute leaf bases (vs. cordate), truncate calyx (vs. distinct, broadly triangular calyx laminae) and 4-merous flowers (vs. 5-merous).

Type:— PERU. Pasco: Province of Oxapampa, Distrito Huancabamba, Sector Oso Playa , Camino a la parcela Oso Playa , 10°19’05”S 75°36’28”W, 2565m, 25 June 2006 (fl), L. Cárdenas, A. Monteagudo, A. Peña, J. Mateo, R. Francis 458 (Holotype: USM!; isotypes: AMAZ, CUZ, HOXA!, HUT, MO!, MOL, USM!) .

Shrub or small tree 3–6m tall. Young stems terete to slightly quadrangular, not winged, and terete with age, the thick nodal collar with interpetiolar flaps 3–7 mm high, deflexed and cucullate, sparsely to moderately covered with glandular projections up to 0.1 mm long, sometimes long and slender, sometimes shorter and globose, usually with very short enations. Leaves opposite, isophyllous; petiole 14–52 mm long, with the same trichomes as the stems; blade 10–19 × 3.2–7.6 cm, elliptic to elliptic-lanceolate, apex long-acuminate, base acute to seldom obtuse, margin thinly hyaline and crenulate-denticulate, membranaceous, acrodromous nerves 3 or 5, suprabasal (the inner pair of secondaries joining the midvein 3–7(–15) mm above the base), plus a very thin, submarginal pair running up to the leaf apex, tertiary complete vein pairs 25–35, always intercalating with additional, incomplete, percurrent veins, midvein, secondary and tertiary veins only impressed, and reticulation barely visible on the adaxial surface, midvein, secondary and tertiary veins strongly prominent, and reticulation prominent or only impressed on the abaxial surface, adaxial surface glabrous, abaxial surface with sparse trichomes similar to the ones on the stems or glabrous. Panicles 27–34 cm long (from which 6.5–12 cm are peduncles), terminal and apparently pendulous, multiflorous, with a single axis and ca. 5 pairs of paraclades, the nodes sometimes with accessory branches, the axis covered with the same indumentum as the branches; bracts and bracteoles not seen. Flowers on pedicels 6–7.1 mm long, 4-merous. Hypanthium ca. 3.6– 4.7 × 5–6.7 mm, campanulate, color unknown, outside glabrous or with very sparse trichomes similar to the ones on young stems and inflorescences, inside glabrous; torus glabrous. Calyx tube 0.4–0.7 mm long, color unknown, truncate to slightly undulate with no distinct sepals internal laminae, margins entire; sepals external projections a mere pointed hump 0.2–0.3 mm long, much shorter than the tube. Petals 11.7–12.3 × 7.8–8.8 mm, red, orbiculate and strongly cucullate, the apex aparently emarginate and asymmetrical, but this must be checked in fresh material since the petals may have ruptured when dried, margin entire, glabrous. Stamens subisomorphic, color unknown; filaments 3.9–4.9 mm long, glabrous and very flat, anthers 4.7–5 mm long, in a 45 o angle to the filament, narrowly oblong but slightly tapering to the apex, this more or less rounded to obtuse, the pore ca. 0.3 mm diam., apical but slightly ventrally inclined, connective not prolonged below the thecae, but projected as a dorsal triangular spur 5.9–6.6 m long, acuminate, lacking an ascending appendage, glabrous. Ovary 4-locular, 1/3 inferior, apex glabrous; style 17–20 mm long, curved at the apex at anthesis, but straight afterwards (before falling), glabrous, stigma capitate. Mature fruits and seeds not seen.

Paratypes:— PERU. Pasco: Provincia de Oxapampa, Dist. Huancabamba, Sector Oso Playa, Margen izquierda del río, 2497 m, 10°19’28”S 75°36’07”W, 20 June 2006 (fl buds), L. Cárdenas & J. Mateo 407 ( AMAZ, CUZ, HOXA!, HUT, MO!, USM!) ; remanente de Bosque, 10°19’21”S 75°34’11”W, 2200 m, 26 June 2004 (fl buds), R. Rojas, & J. Perea 3073 ( HOXA!, MO!) ; Parque Nacional Yanachaga-Chemillén, zona de amortiguamiento, 10°19’05”S 75°36’28”W, 2567 m, 25 June 2008 (fl), A. Monteagudo et al. 16516 ( HOXA!, MO!, USM!) ;

Distribution, ecology, and phenology:— Meriania rubriflora is only known from the Oso Playa area in the North West portion of the Yanachaga-Chemillén National Park, growing in forests or forest remnants at 2200–2600 m elev. ( Figure 2 ). All known specimens have been collected with flowers or flower buds in June.

Conservation Status:— Meriania rubriflora is known from four collections from three neighboring localities, with an EOO of 1.324 km 2 and an AOO of 12 km 2. One of these localities is outside the National Park, and the area is under severe pressure for logging, cattle ranching, farming and hunting. These three localities are all inside the same valley and can be considered just one population. Thus we recommend that this species is considered as Critically Endangered (B1ab; IUCN 2001; IUCN Standards and Petitions Subcommittee 2017).

Etymology:—The specific epithet alludes to the red color of the petals.

Comments:— Meriania rubriflora probably belongs in a group of species mostly from Southern Ecuador and Northern Peru composed of M. almedae Wurdack (1979: 339) , M. radula ( Bentham 1845: 130) Triana (1871: 66) , M. sanguinea (Wurdack 1967b: 4) , and M. tetragona . It shares with these species the red flowers, square to winged stems, and a nodal stipular flap (this last character absent in M. radula ). However, unlike the aforementioned species, M. rubriflora has plinerved leaves with an acute base and smooth adaxial surface (vs. basally nerved leaves with a round to cordate base and bullate to rugose surface), lacks protuberances at the apex of the petiole on the abaxial surface (vs. present), and has four-merous flowers (vs. five-merous flowers). Axinaea pendula Cotton in Cotton et al. (2014: 90) and A. crassinoda Triana (1871: 69) also resemble this group of red-flowered Meriania with their square stems and well-developed nodal stipular flap, but both these species have globose and inflated anther appendages. Axinaea pendula and A. crassinoda also have bullate leaves (unlike M. rubriflora ) and four-merous flowers (like M. rubriflora ). The differences and similarities between these two groups of species in Axinaea and Meriania underscore the blurred lines between these two genera.

Figures

FIGURE 2. Distribution of Macrocentrum andinum and Meriania rubriflora

FIGURE 3. Meriania rubriflora. A. Fertile branch with flower buds. B. Detail of inflorescence wit buds, open flowers and old flowers. C. Detail of branch showing nodal flaps. D. Detail of inflorescence, and ovary in cross section. E. Old flower in longitudinal section. F. Flower, lateral view. G. Flower, lateral view, three petals and five stamens removed. H. Flower bud, lateral view, petals removed. I. Stamens, from left to right, antepetalous—dorsal view, antepetalous-ventral view, anstesepalous, lateral view. A. Monteagudo 16515 (MO); B–I Cardenas 458 (MO).