Eugenia sect. Schizocalomyrtus (Kausel) Mattos, 2005

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

Key to the species of Eugenia sect. Schizocalomyrtus

1. Stamens curved in the bud in longitudinal section ( Figure 2B ); staminal whorls extend to two-thirds of the bud length and deeply tearing at anthesis; fruits densely puberulent and crowned by the remnants of the hypanthium with scars left from stamen insertion ............................................................................................................................................... 5. Eugenia longohypanthiata

- Stamens straight in the bud in longitudinal section; staminal whorls flat ( Figure 1C ) and not tearing at anthesis or less often tearing slightly; fruits glabrous or sometimes densely puberulent and crowned by the reminiscence of the calyx lobes ........................... 2

2. Calyx lobes apparently free but fused at the base to ca. 1 mm long; fruit crowned by the calyx that tears longitudinally by 1 mm long ..................................................................................................................................................................... 2. Eugenia arvensis

- Calyx lobes partially fused to at least 2 mm to completely closed ( Figure 2D, E ); fruits crowned by the calyx that tears evidently, longitudinally or transversely ........................................................................................................................................................... 3

3. Calyx lobes tearing transversely resulting in a calyptra-like structure ( Figure 2F ); fruits usually crowned by the calyx that opens via a calyptra-like structure .............................................................................................................................................................. 4

- Calyx lobes tearing longitudinally resulting in 3–4 lobes; fruits crowned by 3–4 calyx lobes ........................................................ 5

4. Inflorescence thyrsoid, terminal or subterminal; bud closed at the tip leaving an apiculum; bracteoles deciduous after anthesis; ovary with 3–5 ovules per locule ................................................................................................................. 4. Eugenia guanabarina

- Inflorescence fasciculiform, terminal or axillary; bud partially fused and nearly closed leaving four vestigial free lobes at the tip ( Figure 2E ); bracteoles persistent after anthesis; ovary with 9–15 ovules per locule ............................... 6. Eugenia neoriedeliana

5. Leaves dense puberulent abaxially, persistent; the innermost intramarginal vein 4.5–10 mm from the margin; bud tears irregularly at anthesis in 3–4 lobes; fruits 30–45 mm diam. and crowned by the remnant of the irregular calyx lobes ...................................... ...................................................................................................................................................................... 10. Eugenia vattimoana

- Leaves glabrous, pubescent or tomentose abaxially, glabrescent; the innermost intramarginal vein 1.5–5 mm from the margin; bud tears regularly at anthesis in 4 lobes; fruits 7–20 mm diam. and crowned by the remnant of the regular calyx lobes .................... 6

6. Leaves with 5–7 secondary veins, petioles 1.5–5 mm long; bracteoles persistent in the fruit; fruit red when ripe ............................ ..................................................................................................................................................................... 8. Eugenia subterminalis

- Leaves with 9–22 secondary veins, petioles 5–18 mm long; bracteoles deciduous before or after anthesis; fruit artropurpureum or yellowish when ripe .......................................................................................................................................................................... 7

7. Bud glabrous outside, calyx lobes equal in size ............................................................................................................................... 8

- Bud puberulent outside, pubescent or tomentose, calyx lobes two unequal pairs in size ................................................................ 9

8. Young leaves glabrous; buds 5–7 × 4–6.5 mm, calyx lobes 2.5–4 × 2.5–3 mm; staminal whorl 4–5 mm diam., rounded ................ .......................................................................................................................................................................... 3. Eugenia dichasiata

- Young leaves with trichomes 0.2–0.4 mm long, appressed, glabrescent; buds 9–11 × 8–9 mm, calyx lobes 4–8 × 4–9 mm; staminal whorl 9–10 mm diam., squared .................................................................................................................... 7. Eugenia paradisiaca

9. Leaves with secondary veins 11–22 per side; inflorescence rachis 3–30 mm, pubescent, up to one rachis per axil; buds 6–8 × 4.5–7 mm, staminal whorl 4.5 mm diam.; fruits ellipsoid, yellowish when ripe .... ..................................................... 1. Eugenia acutata

- Leaves with secondary veins 9–12 per side; inflorescence rachis 0.5–5 mm, puberulent or tomentose, up to two rachises sharing the same axil; buds 3–5 × 2.5–5 mm, staminal whorl 3 mm diam.; fruits globose, artropurpureo when ripe .................................... ............................................................................................................................................................... 9. Eugenia tenuipedunculata

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 2. Representative illustrations of diagnostic characters of Neotropical genera with flower buds calyptrate, closed or with partially fused calyces. A. Flower bud of Psidium. B. Longitudinal section of the bud of Eugenia longohypanthiata showing the curved stamens along the hypanthium internal wall. C. Longitudinal section of the bud of Myrcia showing curved stamens attached to the hypanthium summit. D. Bud of Eugenia tenuipedunculata with calyx lobes partially fused. E. Bud of Eugenia vattimoana with calyx lobes fused and nearly closed expect for four vestigial free lobes at the tip. F. Bud of Eugenia neoriedeliana opening via calyptra-like structure. G. Bud of Siphoneugena with a constriction.