Eugenia sect. Schizocalomyrtus (Kausel) Mattos (2005: 3)

Giaretta, Augusto, Lucas, Eve & Sano, Paulo Takeo, 2021, Taxonomic monograph of Eugenia sect. Schizocalomyrtus (Myrtaceae: Myrteae), a group within Eugenia with unusual flowers, Phytotaxa 524 (3), pp. 135-177 : 138-141

Eugenia sect. Schizocalomyrtus (Kausel) Mattos (2005: 3) . ( Figures 1 , 3 .)

≡ Schizocalomyrtus Kausel (1967: 367) . Schizocalyx O. Berg (1856c: 319) , nom. illeg., non Scheele (1843: 568, Lamiaceae ), non Hochstetter (1844: Bes. Beil 1, Salvadoraceae ), non Weddell (1854: 73, Rubiaceae , nom. cons.). Calycorectes subgenus Schizocalyx Kiaerskou (1893: 117) . Calycorectes section Schizocalyx Niedenzu (1893: 82) . Calycorectes subgenus Schizocalomyrtus (Kausel) Mattos (1990: 3) .— Type: Schizocalyx pohlianus O.Berg.

= Calycorectes (subgenus Calycorectes section Tetrapetalae ) subsection Subpaniculatae Mattos (1990: 4).— Type: Calycorectes cucullatus Mattos.

= Calycorectes subgenus Eucalycorectes Kiaerskou (1893: 116), nom. inval.— Type: Calycorectes sellowianus O.Berg.

Shrubs or trees 1 to 20 m. Young leaves glabrous or usually glabrescent. Leaves opposite, decussate, petiolate; petiole usually canaliculate; blades oblanceolate to wide-elliptic, chartaceous, usually glabrous; base acute to obtuse; apex acuminate; midvein elevate abaxially; venation brochidodromus, secondary veins usually evident. Inflorescence indeterminate, terminal, subterminal or axillary; rachis with pairs of opposite flowers or branches; flowers pedicellate; bracteoles lanceolate to ovate, free. Flower buds usually obovate, calyx lobes fused, tearing regularly or irregularly at anthesis, less often as a calyptra-like structure; petals (1) 4, white, concave, suborbicular to spathulate; stamens straight, rarely curved; filaments flattened and erect at anthesis, glabrous; anthers yellowish, apertures rimose; staminal whorls not extended above the ovary summit, rarely extending, puberulent, less often pubescent; style usually glabrous, stigma width equal or narrower than the style; ovary with 2-locules, internally glabrous, 3–19 ovules per locule. Fruit crowned by the remnants of the calyx; seeds 1–3; embryo with cotyledons fused and indistinguishable.

Comments:— Eugenia sect. Schizocalomyrtus comprises ten species and can be recognized by leaves with usually well-marked veins and the innermost intramarginal vein far from the margin (2 to 8 mm), the margin not undulate neither hyaline; inflorescences are often fasciculiform with short (0.5 mm long) to elongated (up to 30 mm long) rachises, with up to 3 axes sharing a node, but can be auxotelic, sometimes with a 3-flowered dichasial arrangement, or thyrsoid; flower buds with calyx fused in different lengths along the seam following homosepalous or heterosepalous development patterns but rarely the longohypanthium pattern (see above); fruits globose crowned by lobes torn at anthesis.

Eugenia sect. Schizocalomyrtus is distributed exclusively in the Atlantic forest except for widely distributed species that also occur in the Cerrado (Brazilian savanna) where they are restricted to humid forest along rivers in gallery forest ( Eugenia acutata and E. subterminalis ), and in highland forest East of Paraguay and North of Argentina through Bolivia, to Peru, south Colombia and Ecuador ( E. subterminalis ) ( Figure 3 ). Morphological circumscription and geographic distribution in combination provide reliable diagnosis of Eugenia sect. Schizocalomyrtus .

Figures

FIGURE 1. Diversity of Eugenia sect. Schizocalomyrtus. A–B. Eugenia acutata. A. Auxotelic inflorescence undergoing a second phase of vegetative growth. B. Flowers at anthesis. C–D. Eugenia tenuipedunculata. C. Flowers. D. Immature fruits. E. Eugenia neoriedeliana. Flower opening via transversal tearing at the calyx base resulting in a calyptra-like structure. F. Eugenia guanabarina. Flowers opening via transversal tearing at the calyx base resulting in a calyptra-like structure (S) placed in opposition to a petal (P). G–H. Eugenia longohypanthiata. G. Flower bud tearing irregularly at anthesis. H. Immature fruits crowned by the remnant of the calyx lobes (S) and the hypanthium (H). (A–B: A. Giaretta 1460; C: J.E.Q. Faria 1000; D: A. Giaretta 1493; E: A. Giaretta 1489; F: A. Giaretta 1035; G: A. Giaretta 1500; H: A. Giaretta 1502). Photos by A. Giaretta, except C by J.E.Q. Faria.

FIGURE 3. Distribution of Eugenia sect. Schizocalomyrtus based on herbarium specimens.