Myrtaceae

Key to Neotropical Myrtaceae View in CoL genera with calyptrate, closed, or partially fused calyces

Eugenia sensu Mazine et al. (2014) is recognized among Neotropical genera by tetramerous flowers, rarely penta- or apparently hexamerous ( Giaretta et al., 2019b), stamens straight in the bud ( Vasconcelos et al. 2015), the hypanthium widely flattened and not extended, the ovary 2(3)-locular with few to many ovules per locule, and the embryo with indistinct cotyledons fused into a solid mass ( Landrum & Kawasaki 1997; Sobral 2003; Wilson 2011). Although this combination of characters consistently supports Eugenia , the unusual character of the fused calyx in Neotropical Myrtaceae can mislead taxonomists, particularly when the collection is not simultaneously in flower and fruit. Thus, an identification key for use with flowering or fruiting material is presented to fill this knowledge gap, as well as illustration of these diagnostic characters ( Figure 2 View FIGURE 2 ). This key was tentatively built to be workable with flower or fruits separately or together. Characters such as hypanthium prolonged, type of stigma or inflorescence architecture are persistent in the early fruiting period at least in most specimens observed.

1. Stigma wider than the style ( Figure 2A View FIGURE 2 ) .......................................................................................................................................... 2

- Stigma width equal or narrower than the style ................................................................................................................................. 3

2. Ovary 5–18 locules; fruits with strongly glandular locule walls appearing as false seed coats ................................ Campomanesia View in CoL

- Ovary 2–5 locules; fruits with bony seed coats ..................................................................................................................... Psidium View in CoL

3. Stamens straight in the bud in longitudinal section; hypanthium not prolonged above the ovary summit ...................................... 4

- Stamens semi-curved or strongly curved in the bud in longitudinal section ( Figure 2B, C View FIGURE 2 ); hypanthium prolonged above the ovary summit .............................................................................................................................................................................................. 5

4. Ovary with 2 locules; fruits with 1–3 seeds, embryo swollen .............................................................................................. Eugenia View in CoL

- Ovary with 4 locules; fruits with ca. 40 seeds, embryo curved (C-shaped) .............................................................. Accara elegans View in CoL

5. Inflorescence a panicle or compound-dichasium ............................................................................................................................. 6

- Inflorescence a glomerule, fascicle, raceme, spike, simple-dichasium, superimposed peduncles or less often bracteate shoots .... 7

6. Deciduous calyx lobes tearing regularly into triangular lobes at anthesis; fruit with square scar, embryo curved (C-shaped), whitish ........................................................................................................................................................... Blepharocalyx eggersii View in CoL

- Persistent or deciduous calyx lobes tearing irregularly or opening via calyptra at anthesis, fruit with the remnants of irregular lobes or with a rounded scar, embryo with two foliaceous cotyledons, folded, and greenish ...................................................................... .............................................................. Myrcia View in CoL s.l. (principally in Myrcia View in CoL sects. Calyptranthes View in CoL , Aulomyrcia and Sympodiomyrcia )

7. Flowers with staminal whorls extending up to two-thirds of the bud length, bud tearing deeply at anthesis ( Figure 2B View FIGURE 2 ); fruits crowned by the remnant of the calyx lobes where scars left by stamens insertion are evident, embryo swollen with indistinguishable cotyledons ................................................................................................................................................ Eugenia longohypanthiata View in CoL

- Flowers with staminal whorls flat or at the summit of the prolonged hypanthium, not tearing at anthesis; fruits crowned by remnants of the calyx lobes, stamen scars restricted to the staminal whorl, embryo foliaceous or with two separated plano-convex cotyledons ......................................................................................................................................................................................... 8

8. Stamens semi-curved in the bud in longitudinal section; fruits with 1–5 seeds, embryo with two foliaceous cotyledons, folded, greenish .......................................................................................................................................................................... Myrceugenia View in CoL

- Stamens strongly curved in the bud in longitudinal section; fruits usually with 1–2 seeds, embryo with two separate plano-convex cotyledons, whitish ........................................................................................................................................................................... 9

9. Hypanthium tube constricted at the ovary summit ( Figure 2G View FIGURE 2 ) .................................................................................. Siphoneugena View in CoL

- Hypanthium tube not constricted at the ovary summit ( Figure 2D, E View FIGURE 2 ) .......................................................................................... 10

10. Flowers open via calyptra ( Figure 2F View FIGURE 2 ); fruit with circular scars ................................................................................ Neomitranthes View in CoL

- Flowers opens by regular or irregular tearing of calyx lobes; fruit crowned by calyx lobes remnants ................................... Plinia View in CoL