Meriania callosa 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 : 49-53

3. Meriania callosa Rob. Fern., R. Goldenb. & Michelang. , sp. nov. – Fig. 7–9 .

Holotype: Peru, Amazonas, Prov. Bongará, Dist. Yambrasbamba, ruta desde CP Santa Rosa hacia bosque El Toro , 05°40'07.98"S, 77°55'30.04"W, 1950 m, 11 Nov 2020 (fl.), R. Fernandez-Hilario, W. Chuquitucto & A. Wong 2055 ( MOL barcode 000007 !; isotypes: HOXA accession no. 077833 !, KUELAP accession no. 971 !, MOL barcode 000008 !, NY barcode 04239399 !, UPCB accession no. 99412 !) .

Diagnosis — A species differing from other congeners by the combination of nodes with interpetiolar flaps (0.5–3 mm long), glabrous hypanthia and calyces, calyces with callose dorsal projections, spreading, deep pink corollas, isomorphic stamens, stamen connectives with two appendages, one triangular descending dorsobasal appendage and the other dorsal appendage a mere hump, and spheroid mature ovaries.

Morphological description — Tree up to 18 m tall; young branches and petioles glabrous. Young branches obscurely quadrangular, lacking wings, nodes with interpetiolar flaps, 0.5–3 mm long. Leaves opposite, isophyllous to slightly anisophyllous. Petioles semiterete and adaxially slightly ribbed, 10–22 mm long, without projections. Leaf blades coriaceous, 11–16 × 6.8–10.4 cm, elliptic to oblong, rarely ovate, apex acute to acuminate, base obtuse to rounded, sometimes slightly revolute at base, margin entire, concolorous; venations acrodromous and basal, with one or two pairs of secondaries (lateral nerves) and an additional pair of faint submarginal veins running up to leaf apex, tertiary (transversal nerves) 30–42 on each side of primary, percurrent, 1–11.5 mm distant from each other, midvein, secondary and tertiary veins impressed, reticulation visible on adaxial surface, midvein and secondary veins salient, tertiary veins prominent and reticulation impressed on abaxial surface; adaxial surface flat, yellowish brown, glabrous; abaxial surface yellowish brown, glabrous to sparsely puberulent with short trichomes up to 0.10 mm long. Inflorescences terminal panicles, erect, 14–27.5 × 10–20 cm, few-flowered or submultiflorous; axis and peduncles glabrous. Peduncle 2.4–12.3 cm, quadrangular. Main axis 6–12.5 cm, quadrangular. Paraclades in 3–4 pairs, proximal 6–16.5 cm long, distal 2–3.5 cm long; flowers in regular dichasia at ends of branchlets. Bracts foliaceous, persistent, sometimes caducous, 12–18.2 × 9.2–11.2 cm, petioles 12– 25 mm long, shape and indumentum similar to principal leaves; sometimes with one pair of additional bracts on subproximal nodes of main axis , 12.5–16 × 2.5–8.8 cm, petioles of these 1.5–2 cm long. Bracteoles foliaceous, caducous, 35–36 × 2.5–4 mm, elliptic, petioles 5–6 mm long, indumentum similar to ones on bracts. Flowers 5-merous, with spreading corollas. Pedicels 5–7 mm long, green, glabrous. Hypanthium c. 8.5 × 19 mm, campanulate, green, outer and inner surfaces glabrous; torus glabrous. Calyx opening regularly, green, outer and inner surfaces glabrous; tube 6–7 mm long; lobes repand; with 5 callose dorsal projections, forming irregularly square light green spots, much darker than rest of calyx and hypanthium when dry. Petals 44 × 38–40 mm, 8 mm wide at base, strongly asymmetric obovate, apex rounded, margin entire, deep pink, glabrous. Stamens 10, isomorphic, all bent to one side of flower at anthesis giving flower a zygomorphic appearance; filaments 18– 19 mm, purple, flat, glabrous; connectives not prolonged below thecae, dark purple in thecae, glabrous, with two appendages, one descending dorsobasal, 5.5–6 mm long, triangular, yellow, other dorsal appendage a mere hump, c. 0.25 mm long, rarely inconspicuous, acute, dark purple, 5.5–5.8 mm from tip of descending dorsobasal appendage; anthers 13–14 mm long, lanceolate, dark purple, glabrous, straight, opening by one dorsally inclined pore, thecae surface smooth. Ovary 5-locular, superior, basally fused with hypanthium, free portion c. 7.5 × 7 mm, ovoid and slightly 5-lobed, light purple, 2.5 mm exceeding hypanthium length, glabrous; style c. 19.5 mm long, light purple, glabrous, incurved at apex and opposite anthers at anthesis; stigma punctiform and minutely papillate, 1 mm wide, cream. Fruits capsular (velatidia), with persistent hypanthium and calyx; mature ovary c. 11 × 11–12 mm, spheroid, 4–8 mm exceeding hypanthium length; fruiting pedicels 11.5 mm long. Seeds triangular-linear, c. 1.25 mm long, numerous.

Phenology — Flowering occurs in April and November and fruiting in August and November.

Distribution and ecology — Meriania callosa is endemic to high-elevation montane forests in the Districts of Mariscal Benavides and Yambrasbamba (Amazonas, Peru), between 1880 and 1970 m, on moderately to strongly sloping terrain. Common tree species at this locality “ CP Santa Rosa” (Fernandez-Hilario & al. 2055, 2056) include Alzatea verticillata Ruiz & Pav. ( Alzateaceae ), Cecropia angustifolia Trécul ( Urticaceae ), Ficus mutisii Dugand ( Moraceae ), Graffenrieda emarginata Triana ( Melastomataceae ), M. penningtonii Rob. Fern. & al. ( Melastomataceae ) and Ladenbergia riveroana Standl. ( Rubiaceae ).

Conservation status — Meriania callosa is known from two localities, the CP Santa Rosa and the CP Izcuchaca, both located outside protected areas or conservation areas. In both localities, the forests are fragmented due to the recent increase of deforestation for agriculture and livestock. Therefore, following IUCN (2012, 2019) guidelines and based on an estimated area of occupancy of 8 km 2, we recommend the category Critically Endangered CR B 2ab(iii) for this species.

Etymology — The specific epithet refers to the presence of callose dorsal projections on the calyx of this species.

Discussion — Meriania callosa is distinguished from other congeners by the combination of nodes with interpetiolar flaps (0.5–3 mm long), glabrous flowers, spreading, deep pink corollas, calyces with callose dorsal projections and isomorphic stamens. The callose dorsal projections on the calyx are an unusual feature within Meriania , although some species such as M. hernandi L. Uribe , M. tetragona (Cogn.) Wurdack , M. sanguinea Wurdack may have them. In these species, the projections are less conspicuous and often difficult to see in herbarium material. In addition, M. hernandi ( Ecuador and Colombia) has spreading, orange corollas and M. sanguinea (from Colombia to Peru) and M. tetragona ( Ecuador and Peru) have campanulate, deep red corollas. Meriania penningtonii also has callose dorsal projections and grows sympatrically with M. callosa . However, the projections in both species are different, these being small and whitish in M. penningtonii (see fig. 3 C, D in Fernandez & al. 2021) while in M. callosa they are light green and cover a large part of the calyx. Additionally, M. penningtonii has winged internodes (vs internodes without projections in M. callosa ) and bullate leaves (vs flat). Another species with similar dorsal projections on the calyx is M. fantastica Alvear & al. ( Colombia), although in this species the callose projections are much more evident than in M. callosa (see fig. 4 B in Mendoza-Cifuentes & al. 2014). Meriania callosa is distinguished from M. fantastica by leaf blade size (11–16 × 6.8–10.4 cm vs 15.5–31 × 10.4–20 cm), petal colour (deep pink vs orange) and relative stamen size (isomorphic vs dimorphic in size).

Among Peruvian species, Meriania callosa resembles M. megaphylla (also described here) and M. zunacensis D. Fernández & Dellinger (also in Ecuador). All of them have interpetiolar flaps and spreading corollas, but M. callosa differs from the others by lacking projections at the insertion of the petioles with the leaf blade. Meriania callosa also differs from M. megaphylla by its obscurely quadrangular internodes (vs quadrangular and 4-winged in M. megaphylla ), leaf blades 11–16 × 6.8–10.4 cm with obtuse to rounded bases (vs 21–29.4 × 14.8–22 cm with cordate base), hypanthia c. 8.5 × 19 mm (vs 4.5–5 × 4–4.5 mm) and stamen connectives with dorsal appendages as mere humps (vs blunt, ascending); it differs from M. zunacensis by its leaf blades with entire flat margins (vs revolute at the base in M. zunacensis ), flowers at the ends of branchlets arranged in regular dichasia (vs 4- or 5-flowered umbels), ovary c. 7.5 × 7 mm (vs 13–14.5 × 7–7.5 mm), spheroid when mature (vs pyriform).

Additional specimens examined (paratypes) — PERU: Amazonas, Prov. Bongará, Dist. Yambrasbamba, ruta desde CP Santa Rosa hacia bosque El Toro , 05°40'09.22"S, 77°55'30.05"W, 1970 m, 11 Nov 2020 (fl. bud, fr.), R. Fernandez-Hilario & al. 2056 ( HOXA!, MOL!, NY!, UPCB!) ; Prov. Rodríguez de Mendoza, Dist. Mariscal Benavides, CP Izcuchaca , 06°19'40"S, 77°31'05"W, 1880 m, 30 Aug 1998 (fr.), R. Vásquez & J. Campos 25339 ( NY!) ; same locality, 11 Apr 2001 (fl.), H. van der Werff & al. 16941 ( NY!, USM!) .

Figures

Fig. 7. Meriania callosa – A: terminal fertile branch with inflorescence with detail of interpetiolar flap; B: flower at anthesis, apical view; C: flower bud; D: petal; E: stamen, lateral view; F: fruit, lateral view; G: longitudinal section of flower with petals and stamens removed. – A–G from R. Fernandez-Hilario & al. 2055. – Drawing by Leticia Lajo.

Fig. 8. Meriania callosa – A: leaf blade, abaxial view; B: inflorescence with flower buds; C: flower at anthesis, lateral view; D: flower at anthesis, apical view. – A–D from R. Fernandez-Hilario & al. 2055. – Photographs by Robin Fernandez.

Fig. 9. Distribution map of Meriania callosa, M. escalerensis and M. zunacensis.