Meriania bongarana 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 : 45-49

2. Meriania bongarana Rob. Fern., R. Goldenb. & Michelang. , sp. nov. – Fig. 4–6 .

Holotype: Peru, Amazonas, Prov. Bongará, Dist. Yambrasbamba, Inmediaciones de la Estación Biologica Abra Patricia , 05°41'32.91"S, 77°48'41.1"W, 2320 m, 19–20 Feb 2020 (fl., fr.), R. Fernandez-Hilario, R. Villanueva & L. Pillaca 1930 ( MOL barcode 000006 !; isotypes: CUZ!, HOXA accession no. 077852 !, NY barcode 04239398 !, UPCB accession no. 99400 !) .

Diagnosis — A species differing from other congeners by the combination of ferruginous indumentum evenly covering the abaxial surface of leaves, calyx lobes with claw-shaped dorsal projections (1.5–2.5 mm long), campanulate, pink-orange corollas, isomorphic stamens, stamen connectives prolonged below the thecae and with a slightly crown-shaped descending dorsobasal appendage.

Morphological description — Tree up to 5 m tall; young branches and petioles pubescent with sessile stellate trichomes, these up to 0.10 mm long, moderately to densely on young branches, densely on petioles. Young branches terete-quadrangular, 5–6 mm in diam., lacking wings, nodes without interpetiolar flaps. Leaves opposite, isophyllous. Petioles terete, 1.2–1.5 cm long, without projections. Leaf blades coriaceous, 7.5–9.5 × 3.2–4.3 cm, elliptic, apex acuminate, base acute, margin finely serrulate on distal half to two-thirds, discolorous; venation acrodromous and suprabasal, with one pair of secondaries (lateral nerves), diverging 3–4 mm from base of blade and an additional pair of faint submarginal veins running up to leaf apex, tertiary (transversal nerves) 31–33 on each side of primary, percurrent, 1.5–3.5 mm distant from each other, midvein, secondary and tertiary veins impressed, reticulation barely visible on adaxial surface, midvein and secondary veins salient, tertiary veins prominent and reticulation visible on abaxial surface; adaxial surface flat, light olive to olive-green when dry, glabrous; abaxial surface ferruginous when dry, densely pubescent with sessile stellate trichomes intermixed with elongated trichomes with greatly roughened base, up to 0.5 mm, evenly covering entire surface, with pocket domatia at convergence of midvein and secondary veins. Inflorescences terminal panicles, erect, 7.5–8.2 × 6.8–7 cm, submultiflorous; axis and peduncle densely pubescent with trichomes similar to ones on abaxial surface of leaves, longer (up to 1 mm long) on nodes. Peduncle 2–2.2 cm long, terete-quadrangular. Main axis 3.5–4.8 cm long, terete-quadrangular, with 2–3 pairs of proximal paraclades and two nodes, subdistal node with 4 flowers, distal node with an umbel. Paraclades in one proximal pair, 3.7–4.2 cm long; flowers in 4- or 5-flowered umbels at ends of branchlets. Bracts foliaceous, persistent, 8–9.7 × 3.5–4.2 cm, petioles 1.5–1.8 cm long, shape and indumentum similar to principal leaves; sometimes with one pair of additional bracts on paraclades of main axis , 5.5 × 6.8 cm, petioles 1.2–1.7 cm long. Bracteoles not seen (probably early caducous). Flowers 5-merous, pendant, with campanulate corollas. Pedicels 7–9 mm long, ferruginous, densely pubescent with trichomes similar to ones on inflorescence axis, up to 0.75 mm. Hypanthium 6.5–7 × 4.5 mm, campanulate, ferruginous, outer surface pubescent with trichomes similar to ones on pedicels, inner surface glabrous; torus glabrous. Calyx opening regularly, ferruginous, outer surface densely pubescent with trichomes similar to ones on pedicels, inner surface glabrous; tube 2–2.5 mm long; lobes 2–2.5 × 5–7 mm, acute, each with a claw-shaped dorsal projection, 2–3 mm long. Petals 14–15.5 × 13–16 mm, 3–3.5 mm wide at base, obovate and slightly asymmetric, apex rounded, margin entire, pink-orange, glabrous. Stamens 10, isomorphic, all bent to one side of flower at anthesis giving flower a zygomorphic appearance; filaments 8–8.5 mm, pink to magenta, semiterete, glabrous; connectives prolonged below thecae 1 mm (not including descending dorsobasal appendage), magenta, glabrous, with one descending dorsobasal appendage, c. 1 mm long, slightly crown-shaped, with rounded to irregular lobes up to 0.13 mm; anthers 8.5–9 mm long, lanceolate, magenta, glabrous, with its apical third slightly inflexed, opening by one dorsally inclined pore, thecae surface slightly corrugated. Ovary 5- or 6-locular, superior, basally fused with hypanthium, free portion c. 5 × 3.5 mm, ovate and slightly 5- or 6-costate, magenta, not exceeding hypanthium length, glabrous; style 25.5–27 mm long, magenta, glabrous, incurved at apex and opposite to anthers at anthesis; stigma punctiform and minutely papillate, c. 0.75 mm wide, whitish. Fruits capsular (velatidia), with a persistent hypanthium and caducous calyx; mature ovary c. 7 × 6.5 mm, spheroid, slightly costate, completely concealed by hypanthium; fruiting pedicels 15–17 mm long. Seeds triangular-linear, c. 0.75 mm long, numerous.

Phenology — Flowering and fruiting occur in February.

Distribution and ecology — Meriania bongarana is a Peruvian endemic known from a single locality in the Abra Patricia Conservation Area in the Department of Amazonas, on moderate slopes at 2320 m. At this locality, M. bongarana occurs in undisturbed forests.

Conservation status — The only locality recorded for Meriania bongarana is located between two protected areas, Alto Mayo Protection Forest and Nieva River Reserved Zone. However, the pristine forests in Bongará province are decreasing due to the expansion of agriculture and livestock. Despite being a little-explored region in Amazonas, several endemic species have been discovered in Bongará province in recent years (e.g. Fernandez-Hilario & al. 2020b; Fernandez-Hilario & al. 2021; Tejedor & Calatayud 2017). Therefore, following IUCN (2012, 2019) guidelines and based on an estimated area of occupancy of 4 km 2, we recommend the category Critically Endangered CR B 2ab(iii) for this species.

Etymology — The specific epithet refers to Bongará province (Department of Amazonas) in N Peru.

Discussion — Meriania bongarana belongs to a group of species characterized by campanulate, reddish orange corollas, and calyx lobes usually with claw-shaped to falcate dorsal projections. The species of this group occur in the Andes from Venezuela to N Peru. Meriania dazae Rob. Fern. & al. and M. bongarana are the only species in this group recorded for Peru. Within this group the most similar species to M. bongarana are M. cuneifolia Gleason , M. furvanthera Wurdack and M. stellata (Gleason) Wurdack , all endemic to Ecuador. However, M. bongarana differs from the first by its hypanthia 6.5–7 mm long (vs 4–5 mm in M. cuneifolia ), petals 14–15.5 mm long (vs 10–13.5 mm), isomorphic stamens (vs dimorphic in size) and connectives prolonged below the thecae 1 mm (vs prolonged 1.3–1.7 mm). It differs from the second by its hypanthia terete (vs obscurely ribbed in M. furvanthera ), calyx lobes with dorsal projections 2–3 mm long (vs c. 0.5 mm) and petals 14–15.5 mm long (vs 21–22.5 mm). It differs from the third by its inflorescences and hypanthia densely pubescent (vs densely villose in M. stellata ), hypanthia terete (vs obscurely ribbed), isomorphic stamens (vs dimorphic in size) and stamen connectives with descending dorsobasal appendages c. 1 mm long (vs 0.25–0.4 mm).

The only Peruvian species with features similar to Meriania bongarana is M. dazae . Both species can be distinguished by the colour of the leaf blades on the abaxial surface (ferruginous in M. bongarana vs whitish to cream in M. dazae ), petal length (14–15.5 mm vs 19.5–24 mm) and the dorsal appendages of stamen connectives (absent vs a mere hump, 0.25 mm long). Other Peruvian species such as M. acida (Markgr.) Wurdack and M. tomentosa (Cogn.) Wurdack can be confused with M. bongarana because they share the campanulate, pink-orange to reddish orange corollas. However, these two species have calyptrate calyces without dorsal projections (vs lobed calyces with falcate dorsal projections in M. bongarana ) and with irregular dehiscence (vs regular dehiscence). Furthermore, M. bongarana differs from M. acida by the size of the leaf blades (7.5–9.5 × 3.2–4.3 cm vs 12–18 × 5–9 cm), inflorescence position (terminal vs pseudolateral) and petal size (14–15.5 mm long vs 10 mm long). Meriania bongarana differs from M. tomentosa by its inflorescences 7.5–8.2 cm long (vs 19.9–32.3 cm), stamen connectives with crown-shaped descending dorsobasal appendages (vs blunt) and magenta thecae (vs cream).

Figures

Fig. 4. Meriania bongarana – A: terminal fertile branch with inflorescence with detail of leaf margin; B: inflorescence branch; C: flower at anthesis, lateral view; D: petal; E: stamen, lateral view; F: ovary and style; G: hypanthium and calyx, longitudinal section. – A–D from R. Fernandez-Hilario & al. 1930. – Drawing by Leticia Lajo.

Fig. 5. Meriania bongarana – A: leaf blade, abaxial view; B: inflorescence with flower buds; C: terminal fertile branch with inflorescence; D: fruits. – A–D from R. Fernandez-Hilario & al. 1930. – Photographs by Robin Fernandez.

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