Meriania Sw., nom. cons., Fl. Ind. Occ. 2: 823, t. 15. 1798. (Figures 3–7). Type species: Rhexia leucantha Sw., type cons. [= Meriania leucantha (Sw.) Sw.]. Trees or shrubs, rarely climbers, distal branchlets glabrous or with various indument types. Young branches terete, quadrangular, or 4-winged; nodes with interpetiolar lines, flaps or without modifications. Leaves opposite, isophyllous to slightly anisophyllous. Petioles with projections or without modifications. Leaf blades petiolate or sessile, sometimes subpeltate or peltate; venation acrodromous basal or suprabasal; glabrous or covered with various indument types. Inflorescences terminal or pseudo-lateral (initially terminal but overtopped by the developing axillary bud) panicles, rarely dichasia, or solitary flowers. Flowers (4–)5–6-merous; diplostemonous; with spreading to campanulate corollas. Hypanthium terete to costate; glabrous or covered with various indument types. Calyx lobed, repand, truncate, subcalyptrate or calyptrate; dehiscence regular, irregular or circumscissile; with dorsal projections, acicular, claw-shaped, conic, callose, blunt or obsolete; glabrous or covered with various indument types. Petals oblong, obovate, slightly obovate, or strongly asymmetrically obovate; glabrous, rarely puberulent or slightly ciliate. Stamens isomorphic to strongly dimorphic, all bent to one side of the flower at anthesis giving the flower a zygomorphic appearance; filaments flat to semiterete; connectives sometimes prolonged below the thecae or abruptly inflated (bulbous), with two appendages, one dorso-basal and the other dorsal, the former descending or almost perpendicular to the thecae, sometimes laterally expanded, the latter obsolete to ascending; anthers usually opening by one dorsally inclined pore, thecae with smooth to corrugated surfaces. Ovary superior, sometimes ½ inferior, usually glabrous; style incurved at the apex and opposite to the anthers at anthesis, glabrous. Fruits capsular (velatidia), with persistent hypanthium, calyx persistent or caducous; mature ovary exceeding the hypanthium length or completely concealed by the hypanthium. Seeds triangular-linear, numerous. Distribution and habitat:— Peru presents 36 species of Meriania, of which 25 are endemic. Twenty-four species were found in northern Peru within the Amotape-Huancabamba Zone (see Weigend 2002, Tejedor & Calatayud 2022) (Table 1), which holds the highest species richness in Peru. The departments with the highest number of species are Amazonas (18 species), Cajamarca (11 species) and San Martín (9 species) (Figure 7). Most species have restricted distributions, and only four species (M. neilli, M. radula, M. sanguinea and M. tomentosa) occur in more than five departments. The Peruvian species of Meriania grow mainly in the eastern flanks of the Andes in premontane forests, montane forests, elfin forests and subparamos at 350–3500 m, but two species (M. escalerensis and M. microflora) grow in the sub-Andean cordilleras (Andean Tepuis sensu Neill et al. 2014).

Published as part of Fernandez-Hilario, Robin, Goldenberg, Renato & Michelangeli, Fabián A., 2023, A synopsis of Meriania (Melastomataceae: Merianieae) in Peru, pp. 1-101 in Phytotaxa 602 (1) on pages 7-8, DOI: 10.11646/phytotaxa.602.1.1, http://zenodo.org/record/8141984