Meriania megaphylla Rob. Fern., R. Goldenb. & Michelang., 2022

Rocío, Robin Fernandez-Hilario, Gonzáles, Pilar Rojas, Villanueva-Espinoza, Rosa, Lajo, Leticia, Wong Sato, Akira A., Paredes-Burneo, Diego, Pillaca-Huacre, Luis, Michelangeli, Fabián A. & Goldenberg, Renato, 2022, Nine new species and a new country record for Meriania (Melastomataceae) from Peru, Willdenowia 52 (1), pp. 39-74 : 61-63

7. Meriania megaphylla Rob. Fern., R. Goldenb. & Michelang. , sp. nov. – Fig. 6 , 14 .

Holotype: Peru, La Libertad, Prov. Pataz, Dist. Ongón, valle del río Mixiollo , 2000–2100 m, 4 Aug 1914 (fl.), A. Weberbauer 7048 ( MOL barcode 00003237 !; isotypes: F-fragment accession no. 628681 !, MOL-fragment barcode 00003236 !) .

Diagnosis — A species differing from other congeners by the combination of 4-winged and quadrangular branches, interpetiolar flaps (5–8 mm long), large leaf blades (21– 29.4 × 14.8–22 cm), spreading, reddish purple corollas, isomorphic stamens, and stamen connectives with two appendages, one a triangular descending dorsobasal appendage and the other a blunt ascending dorsal appendage.

Morphological description — Scandent shrub; young branches and petioles glabrous. Young branches quadrangular, 4-winged, 5–11 mm in diam., nodes with interpetiolar flaps, 5–8 mm long. Leaves opposite, slightly anisophyllous. Petioles quadrangular, 7.6–11.6 cm long, with an adaxial projection (scutum) at insertion of petiole with leaf blade, up to 1 mm tall, obscured by trichomes. Leaf blades coriaceous, 21–29.4 × 14.8–22 cm, ovate, apex broadly obtuse, base cordate, margin finely serrulate, concolorous; venation acrodromous and basal, with three pairs of secondaries (lateral nerves) and an additional pair of faint submarginal veins running up to leaf apex, tertiary (transversal nerves) 38–40 on each side of primary, percurrent, 2–10 mm distant from each other, midvein, secondary and tertiary veins impressed, reticulation visible on adaxial surface, midvein and secondary veins salient, tertiary veins and reticulation prominent on abaxial surface; adaxial surface bullate; both surfaces light olive when dry, glabrous. Inflorescences terminal panicles, erect, c. 25.9 × 10 cm, multiflorous; axis and peduncle glabrous. Peduncle c. 8.9 cm long, quadrangular, 4-winged. Main axis c. 15.6 cm long, quadrangular, 4-winged. Paraclades in 5 pairs, proximal c. 8.8 cm long, distal c. 2.2 cm long; flowers in 5-flowered umbels at ends of branchlets. Bracts foliaceous, persistent, 3.7–6 × 1.5–1.8 cm, petioles 8–13 mm long, elliptic, indumentum similar to ones on leaves. Bracteoles not seen (probably early caducous). Flowers 5–merous, with spreading corollas. Pedicels 6–8 mm long, colour unknown, glabrous to sparsely puberulent with short trichomes, up to 0.10. Hypanthium 4.5–5 × 4–4.5 mm, campanulate, colour unknown, outer and inner surface glabrous to sparsely puberulent with trichomes similar to ones on pedicels; torus glabrous. Calyx opening regularly, colour unknown, outer and inner surface glabrous to sparsely puberulent with trichomes similar to ones on pedicels; tube 1.5–2 mm long; lobes repand; with 5 blunt dorsal projections, c. 0.5 mm long. Petals 20.5–22.5 × 19–21 mm, 2.5–3 mm wide at base, strongly asymmetrically obovate, apex asymmetric, margin entire, reddish purple, glabrous. Stamens 10, isomorphic, all bent to one side of flower at anthesis giving flower a zygomorphic appearance; filaments 10.5–11 mm long, colour unknown, flat, glabrous; connectives not prolonged below thecae, colour unknown, glabrous, with two appendages, one descending dorsobasal, 4–4.5 mm long, triangular, other ascending dorsal appendage, c. 0.75 mm long, blunt and c. 4.5 mm from tip of descending dorsobasal appendage; anthers 8–8.5 mm long, lanceolate, colour unknown, glabrous, straight, opening by one dorsally inclined pore, thecae surface corrugated. Ovary 5–locular, superior, c. 4.5 × 3 mm, oblong, colour unknown, not exceeding hypanthium length, glabrous; style 11.5–13.5 mm long, colour unknown, glabrous, incurved at apex and opposite to anthers at anthesis; stigma punctiform and minutely papillate, c. 0.5 mm wide, colour unknown. Fruits and seeds not seen.

Phenology — Flowering occurs in August.

Distribution and ecology — Meriania megaphylla is endemic to high-elevation montane forests in the Pataz province (Department of La Libertad), between 2000 and 2100 m. The vegetation of this region is part of the relict montane forests from the W slopes of the Andes in NW Peru (see Weigend & al. 2005).

Conservation status — Meriania megaphylla is known from a single collection made in 1914. Increased deforestation in recent years and artisanal mining threaten the montane forests of Pataz. However, because these crucial forests are at present virtually unknown, we propose that at this time M. megaphylla be considered as Data Deficient DD ( IUCN 2012, 2019).

Etymology — The specific epithet refers to the unusually large leaves of this species.

Discussion — Meriania megaphylla is distinguished from other species within the genus by the combination of quadrangular and 4-winged internodes, nodes with interpetiolar flaps, an adaxial projection (scutum) at the insertion of the petiole with the leaf blade and large leaf blades (21–29.4 × 14.8–22 cm). Quadrangular and winged internodes also occur in M. tetragona ( Ecuador and Peru), M. penningtonii ( Peru) and M. nobilis Triana ( Colombia), but only M. penningtonii lacks interpetiolar flaps on the nodes (vs present in the other species). Additionally, M. nobilis has leaf blades with flat adaxial surfaces (vs bullate in M. megaphylla ), revolute margins at the base (vs entire) and dimorphic stamens (vs isomorphic). In addition, M. megaphylla differs from M. tetragona by its petioles with adaxial projections (vs abaxial projections), leaf blades 21–29.4 × 14.8–22 cm (vs 7–12 × 3–9 cm) and spreading, reddish purple corollas (vs campanulate, deep red).

Due to the large bullate leaf blades and spreading, reddish purple corollas, the type specimen of Meriania megaphylla ( Weberbauer 7048) had been erroneously identified as M. tetraquetra Triana , a poorly known species endemic to N Peru (Department of Amazonas). However, M. tetraquetra probably belongs in a group of species that includes M. penningtonii and M. rugosa Markgr. , these also endemic to N Peru. These species are trees with bullate leaves, spreading corollas, reddish purple petals, isomorphic stamens, and stamen connectives with two appendages, one a triangular descending dorsobasal appendage and the other dorsal appendage a mere hump or absent. Within this group M. megaphylla differs from M. penningtonii by its petioles with adaxial projections (vs absent), calyces with blunt dorsal projections (vs callose) and stamens connectives with blunt ascending appendages (vs mere humps). Also, M. megaphylla can be distinguished from M. tetraquetra and M. rugosa by its quadrate and 4-winged internodes (vs quadrate but not winged in M. tetraquetra and M. rugosa ), ovate, 21–29.4 × 14.8–22 cm leaf blades (vs oblong, 27–35 × 13–20 cm in M. tetraquetra and elliptic, 15–17 × 7–8 cm in M. rugosa ), calyx with blunt dorsal projections, c. 0.5 mm long (vs absent in M. tetraquetra and blunt, 2–3 mm long in M. rugosa ) and stamen connectives with ascending blunt dorsal appendages (vs absent in M. tetraquetra and M. rugosa ).

Meriania is traditionally characterized by its arboreal or shrubby habit with the exception of M. selvaflorensis Humberto Mend. ( Colombia) which has a lianescent habit. The lianescent habit is also present in other genera within of the Merianieae ( Adelobotrys and Graffenrieda ). However, according to the label information on Weberbauer 7048, M. megaphylla has a scandent habit. Meriania megaphylla is easily distinguishable from M. selvaflorensis by its quadrangular and 4-winged branches (vs terete), developed interpetiolar flaps (vs absent), bullate leaf blades (vs flat) and lobed calyx (vs calyptrate).

Figures

Fig. 6. Distribution map of Meriania bongarana, M. hirsuta, M. juanjil and M. megaphylla.

Fig. 14. Meriania megaphylla – A: terminal fertile branch with inflorescence; B: detail of interpetiolar flap; C: detail of leaf base; D: flower at anthesis, apical view; E: stamen, lateral view; F: petal; G: flower with petals and stamens removed. – A–G from A. Weberbauer 7048.