Meriania juanjil 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 : 58-61

6. Meriania juanjil Rob. Fern., R. Goldenb. & Michelang. , sp. nov. – Fig. 6 , 13 .

Holotype: Peru, Amazonas, Prov. Bongará, Montane rainforest along Yambrasbamba-Pomacocha trail between Yambrasbamba andYanayacu , 2200–2300 m, 26 Jun 1962 (fl.), J. Wurdack 1054 ( USM accession no. 27403 !; isotypes: F accession no. 1601214 !, NY barcode 02499960 !, P barcode 05225706 !, US barcode 02925052 !) .

Diagnosis — A species differing from other congeners by the combination of elliptic leaf blades (10.8–12.7 × 2.7–3 cm) with moderately puberulent indumentum on the abaxial surfaces, 3-nerved venation, subcalyptrate calyces with small conic dorsal projections (0.5 mm long) and irregular dehiscence, campanulate, pink-orange corollas and isomorphic stamens.

Morphological description — Shrub up to 5 m tall; young branches and petioles puberulent, glabrescent to sparsely so on young branches with stellulate trichomes up to 0.13 mm long, sparsely to moderately on petioles with stellate trichomes up to 0.13 mm long. Young branches quadrangular, 4–5.5 mm in diam., lacking wings, nodes without interpetiolar flaps and leaf axils moderately covered with elongate, slightly roughened trichomes up to 2 mm long. Leaves opposite, isophyllous. Petioles quadrangular, 1.8–2.3 cm long, without projections. Leaf blades coriaceous, 10.8–12.7 × 2.7–3 cm, elliptic, apex acute, base acute to slightly obtuse, margin entire, discolorous; venation acrodromous and suprabasal, with one pair of secondaries (lateral nerves), diverging 3–4.5 mm from base of blade and an additional pair of faint submarginal veins running up to leaf apex, tertiary (transversal nerves) 27–32 on each side of primary, percurrent, 1.5–5 mm distant from each other, midvein and secondary veins impressed, tertiary veins and reticulation barely to not visible on adaxial surface, midvein and secondary veins salient, tertiary veins prominent, reticulation impressed on abaxial surface; adaxial surface flat, dark olive when dry, glabrous; abaxial surface light olive when dry, midvein and secondary veins moderately puberulent with stellate trichomes up to 0.13 mm long intermixed with elongated slightly roughened trichomes up to 0.5 mm long, secondary veins and reticulation sparsely puberulent with only stellate trichomes, with elongated slightly roughened trichomes up to 1 mm long at convergence of midvein and secondary veins. Inflorescences pseudolateral panicles (initially terminal but overtopped by developing axillary bud), erect, 6.8–10 × 4.8–8.3 cm, submultiflorous or multiflorous; axis and peduncle moderately puberulent with stellate trichomes up to 0.13 intermixed with elongated trichomes with a substellate base up to 0.75 mm, longer (up to 1.5 mm long) on nodes. Peduncle 1.8–2.4 cm long, quadrangular. Main axis 5.2–5.9 cm, quadrangular, with 2(or 3) pairs of proximal paraclades and two nodes, subdistal node with 3 pairs of flowers, distal node with an umbel. Paraclades in proximal pairs, 3.8–4.5 cm long; flowers in 5–7-flowered umbels at ends of branchlets. Bracts foliaceous, persistent, 7–10.5 × 1.8–2.9 cm, petioles 1.6–3.4 cm long, shape and indumentum similar to principal leaves; sometimes with one pair of additional bracts on subproximal paraclades of main axis , 4.1–6.5 × 1–1.6 cm, petioles 1.8–2 cm long. Bracteoles not seen (probably early caducous). Flowers 5-merous, pendant, with campanulate corollas. Pedicels 6–8 mm long, colour unknown, moderately puberulent covered with trichomes similar to ones on peduncle and axis. Hypanthium c. 3.5 × 4 mm, campanulate, colour unknown, outer surface moderately puberulent covered by trichomes similar to ones on pedicels, inner surface glabrous; torus glabrous. Calyx opening irregularly, colour unknown, outer surface moderately puberulent with stellate trichomes up to 0.13 mm long, inner surface sparsely puberulent with similar trichomes; calyx lobes closely connate in bud, forming a subcalyptra, 3–3.5 mm long, each with a small conic dorsal projection, 0.5 mm long, at maturity splitting irregularly into 2–3 segments, segments irregularly acute to obtuse. Petals 11–13.5 × 10–12.5 mm, c. 2 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 giving flower a zygomorphic appearance; filaments 6.5–7 mm long, colour unknown, flat, glabrous; connectives prolonged below thecae c. 0.5 mm (not including descending dorsobasal appendage), colour unknown, glabrous, with one descending dorsobasal appendage, c. 0.75 mm long, acute; anthers 5.5–6 mm long, lanceolate, colour unknown, glabrous, straight or with apices slightly reflexed, opening by one apical to slightly dorsally inclined pore, thecae surfaces smooth. Ovary 5-locular, superior, free, c. 3 × 2.5 mm, oblong and slightly 5-lobed, colour unknown, not exceeding hypanthium length, glabrous; style c. 22.5 mm long, colour unknown, glabrous, slightly incurved at apex and opposite to anthers at anthesis; stigma punctiform and minutely papillate, c. 0.8 mm wide, colour unknown. Fruits and seeds not seen.

Phenology — Flowering occurs in June.

Distribution and ecology — Meriania juanjil is endemic to high-elevation montane forests in Bongará province in the Department of Amazonas, on moderately sloping terrain at 2200–2300 m.

Conservation status — Meriania juanjil is known from a single collection from Bongará province. Currently, the pristine forests in the Bongará province are decreasing due to the expansion of agriculture and livestock (see additional comments under M. bongarana ). 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 “juanjil ” refers to the name applied by local people in Bongará to the Melastomataceae . Because the epithet is a noun in apposition, it retains its own termination irrespective of the gender of the generic name (see Turland & al. 2018: Art. 23.5).

Discussion — Meriania juanjil is clearly distinguished from other species within the genus by the combination of subcalyptrate calyces with small conic dorsal projections (c. 0.5 mm long) and irregular dehiscence, campanulate, pink-orange corollas and isomorphic stamens. The calyx lobes are closely connate in bud, forming a subcalyptra or calyptra, a feature present in other genera within Merianieae (such as Centronia and Graffenrieda ) and outside the tribe (e.g. Alloneuron Pilg. , Miconia Ruiz & Pav. , Mouriri Aubl. , Wurdastom B. Walln. ). Meriania species with these characteristics can be separated into two artificial groups, the first one with species with spreading corollas (e.g. M. brachycera (Naudin) Humberto Mend. & Fern. Alonso , M. escalerensis , M. kirkbridei Wurdack , M. maguirei Wurdack ) and the second one with campanulate corollas (e.g. M. acida , M. grandiflora (Standl.) Almeda , M. phlomoides (Triana) Almeda , M. tomentosa , M. vasquezii ). Within the latter group, M. juanjil is similar to M. denticulata ( Ecuador) and M. vasquezii , also described here from Peru (see comments under the latter for differences). These three species share the subcalyptrate calyx with small dorsal projections and irregular dehiscence. However, M. juanjil is distinguished from M. denticulata by its leaf blades 10.8–12.7 × 2.7–3 cm [vs 9–21(–24) × 5–12(–17) cm] and 3-nerved [vs 5(–7)-nerved] and petals 11–13.5 × 10–12.5 mm (vs 8–10 × 7–8 mm).

In Peru, there are three other species of Meriania with a calyptrate calyx [ M. acida , M. escalerensis (also described here) and M. tomentosa ], but none of them has dorsal projections on the calyx. Meriania escalerensis differs from the other species by its calyces with circumscissile dehiscence (vs irregular dehiscence) and spreading, reddish purple corollas (vs campanulate, pink-orange to reddish orange corollas). Additionally, M. juanjil is distinguished from M. acida and M. tomentosa by its subcalyptrate calyx (vs calyptrate) and also differs from the former by its leaf blades 2.7–3 cm wide (vs 5–8 cm wide) and petals 11–13.5 mm long (vs 9–10 mm long). Meriania juanjil differs from the latter by its abaxial leaf surface with trichomes only on the nerves (vs evenly covering the entire surface) and inflorescences 6.8–10 cm long (vs 19.9–32.3 cm long).

Figures

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

Fig. 13. Meriania juanjil. Terminal fertile branch with inflorescences; B: detail of convergence of midvein and secondary veins, abaxial view; C: detail of calyx apex; D: inflorescence branch; E: stamen, lateral view; F: petal; G: flower with petals and stamens removed. – A–G from J. Wurdack 1054.