Eugenia guanabarina (Mattos & D.Legrand) Giaretta & M.C.Souza

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 : 153-154

4. Eugenia guanabarina (Mattos & D.Legrand) Giaretta & M.C.Souza (in Giaretta et al. 2018: 284).

≡ Marlierea guanabarina Mattos & D.Legrand (in Legrand & Mattos 1975: 6). Type:— BRAZIL. Rio de Janeiro: Recreio do Bandeirantes, Pedra de Itaúna , fl., 22 [July] 1965, N. Santos 5967 (holotype: MVM [18113 herbarium number-photo!]; isotype: R). ( Figures 1F , 11 ).

= Mitranthes langsdorffii O. Berg (1859: 595) . Chytraculia bergiana Kuntze (1891: 238) , non Chytraculia langsdorffii (O.Berg) Kuntze (1891: 238) . Neomitranthes langsdorffii (O.Berg) Mattos (1981: 2) , non Eugenia langsdorffii O. Berg (1859: 568) . Type:— BRAZIL. Bahia, fl., s.d., Blanchet 2309 (lectotype designated by Giaretta et al. (2018): LE!; isolectotypes: F [69177 negative number-photo!], G! [00222536-2 sheets, 00222537-2 sheets], K! [000018787], NY [00405346-photo!], P! [00162722, 05232287], W!). Remaining syntype:— BRAZIL. Bahia, ‘in silvis ad flumen Itahype prope Castel novo’, s.d., Riedel s.n. (G! [00222538, 00222539-2 sheets], K! [000331517], LE! [6 sheets], M [0146829-photo!], MEL [666925-photo!], P! [05232220, 05232222, 05232223], W! [2 sheets]).

= Calycorectes teixeireanus Mattos (1996b: 1) . Eugenia teixeireana (Mattos) Mattos (2005: 9) . Type:— BRAZIL. Rio de Janeiro, Barra da Tijuca, fl., 13 July 1964, W. Hoehne 5759 (holotype: SP! [001302]; isotypes: FLOR, MBM! [herbarium number 69215], NY [00886386-photo!], UEC).

Shrubs or trees 2 to 13 m tall. Young leaves with light-brownish trichomes 0.5–1 mm long, appressed, moderately sparse abaxially, glabrate adaxially, glabrescent. Leaves with petioles 7–12 × 1.5–2 mm; blades 5–18 × 2.5–7 cm, elliptic or narrow-elliptic; base acute, cuneate or obtuse; apex acuminate, 0.5–3.5 cm long, or narrowly acute, rare obtuse; midvein canaliculate adaxially; secondary veins 8–12 per side; marginal veins two, the innermost 1.5–3.5 mm from the margin, the outermost 0.5–1 mm from the margin. Inflorescence terminal or subterminal, thyrsoid; bract 1.5–2.5 × 1–1.2 mm, wide-ovate; rachis 5–80 mm long; 1–4 pairs of lateral axes emerging from the rachis, lateral axes becoming shorter towards the apex, 5–40 mm long, flattened, puberulent; each lateral axes with 3 to 7-flowered dichasial arrangement, middle flower sessile, lateral flowers with pedicels 3–10 × 0.5 mm; one rachis per axil, rarely two; bracteoles 1–2 × 1–1.5 mm, ovate or wide-ovate, puberulent, deciduous after anthesis. Flower buds 3–6 × 2.5–4 mm, obovate, calyx lobes fused and closed at the tip leaving an apiculum 0.3–1.5 mm long, tearing transversely at the calyx base resulting in a structure calyptra-like, 3–5 mm diameter, rare tearing irregularly in 3–4 lobes, puberulent, usually dense on hypanthium outside; petals (1) 4, 2.5–3.5 × 3–4.5 mm, obovate, sometimes irregular; stamens straight in the bud, filaments up to 6 mm long, anthers 0.5–1 mm long; staminal whorls flat, 3.5–5 mm diameter, rounded, not tearing at anthesis; style 3–5 mm long; ovary 2–locules, 3–5 ovules per locule. Fruits 12–14 × 14–16 mm, globose, atropurpureo when ripe, glabrous, often crowned by the remnant of the calyx calyptra-like; seeds 1–2.

Etymology:— The specific epithet likely refers the type location of the Guanabara state, a previous name for Rio de Janeiro state used between 1960 and 1975.

Distribution and habitat:— Eugenia guanabarina is distributed in Southeastern (Espírito Santo and Rio de Janeiro) and Northeastern (Bahia) Brazil, often known from lowland coastal vegetation at elevations between 0 to 120 m ( Figure 12 ). Eugenia guanabarina is usually a small tree occurring in shrubby vegetation of Restinga, and also occurs as a tall tree in forest vegetation on non-marine sandy soil locally called Muçununga ( Peixoto et al. 2008), both within the Ombrophilous Dense Forest in the Atlantic forest.

Phenology:— Flowers of Eugenia guanabarina have been mainly collected from July to November and less often from March to May, and fruiting from August to April ( Figure 6 ).

Conservation status:— Eugenia guanabarina is known in seven protected areas (APA Lagoa Encantada, APA de Conceição da Barra, PES de Itaúnas, REBIO de Poço das Antas, REBIO de Una, RESEX Cassuruba, RPPN Reserva da Vale) and non-protected areas with broad EOO (173,938.3 km ²). Although it is not threatened, human disturbance of coastal environments has a negative impact on natural populations. Thus, it is suggested that this species should be rated as Least Concern (LC).

Comments:— Misleading taxonomy surrounding Eugenia guanabarina arose from the combination of a fused calyx in the bud usually opening via a calyptra-like structure and a thyrsoid inflorescence, features commonly associated with Myrcia s.l., and the embryo with fused cotyledons that suggests a relationship to Plinninae (sensu Lucas et al. 2007) and Eugenia ( Souza 2009) . Eugenia guanabarina was previously accepted under Neomitranthes Kausel ex D.Legrand (in Legrand & Klein 1977: 671) ( Mattos 1981). However, phylogenetic reconstruction consistently recovered E. guanabarina within Eugenia ( Giaretta et al. 2019b) , reinforced by straight stamens in the bud, in opposition to the strongly curved stamens in Myrcia s.l. and the ‘ Plinia group’ ( Vasconcelos et al. 2015). The combination of the thyrsoid inflorescence and buds tearing via calyptra-like structures are convenient characters to recognize Eugenia guanabarina . Alternatively, the thyrsoid can also be more depauperate in some collections. In such cases, Eugenia guanabarina can be confused with E. acutata but differs by the 8-12 secondary veins (vs. 11-22), bracteoles ovate or wide-ovate (vs. lanceolate), flowers with staminal whorls rounded (vs. squared) and not tearing at anthesis (vs. slightly tearing), and fruit purplish when ripe (vs. yellowish). Chytraculia bergiana is a replacement name for Mitranthes langsdorffii , the earliest available basionym. However, the new combination is unavailable in Eugenia due to preexistence of Eugenia bergiana Grisebach (1860: 182) . Thus, Marlierea guanabarina is the earliest name available to be combined ( Giaretta et al. 2018). Although the epithet has an improper Latin termination, the original spelling must be retained since it does not fit any conditional rule of the Code (see Art. 60).

Specimens examined:— BRAZIL. Bahia: Arraial D’Ajuda , 29 August 1961, fl., A . P . Duarte 6058 ( K!, RB!, SPF!); Belmonte , 27 September 1979, fl., L . A . Mattos-Silva 614 ( CEPEC!, K!, RB!); Caravelas , 9 October 2007, fl., H . M . Dias 297 ( RB!, SPF!, VIES!); Mucuri , s.d., fl., T . S . Santos 942 ( CEPEC!); Porto Seguro , 25 August 1988, fl., L . A . Mattos-Silva 2515 ( CEPEC!, K!, SP!); Una , 10 September 2006, es., M . C . Souza 385 ( RB!), 28 February 1986, fl., T . H . Brito 4066 ( CEPEC!) . Espírito Santo: Conceição da Barra , 25 July 1992, fl., O . J . Pereira 3764 ( RB!), 5 September 2011, fl., A . Giaretta 1026 ( RB!, SPF!, VIES!), 7 July 2012, fl., L . F .T. Menezes 2042 ( VIES!), 7 September 2011, fl., A . Giaretta 1035 ( RB!, SPF!, VIES!); Linhares , 27 August 1991, fl., D. A . Folli 1394 ( RB!), 7 July 1983, fl., D. A . Folli 449 ( CEPEC!, RB!); São Mateus , 31 January 2016, fl. and fr., A . Giaretta 1629 ( SPF!), 31 January 2016, fl., A . Giaretta 1630 ( SPF!) . Rio de Janeiro: Barra da Tijuca , 10 September 1970, fr., P . J . Fontella 424 ( MBM!, RB!); Maricá , 11 May 2012, fl., I . E . Santos 809 ( HB!, RB!); Recreio dos Bandeirantes , 17 May 1964, fl., N . Santos 5131 ( R!), 9 August 1964, fl., N . Santos 5201 ( R!); Rio de Janeiro, 2 September 1969, fl., D. Sucre 5905 ( RB!, SPF!), 8 June 1973, fl., E . A . Montalvo 100 ( RB!); Saquarema , 12 February 1992, fr., D. S . D. Araujo 9581 ( GUA!, RB!), 29 March 2000, fl. and fr., C . Farney 4036 ( RB!, SPF!) .

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 6. Frequency distribution (n) of flowering (black-line triangle) and fruiting (grey-filled triangle) stages based on herbarium material of Eugenia sect. Schizocalomyrtus.

FIGURE 11. Eugenia guanabarina. A. Leaf twig with flowers. B. Inflorescence with flowers in dichasial arrangement. C. Fruits; arrows showing the remnant of the calyx calyptra-like. (A: A. Giaretta 991; B: C. Farney 4036; C: A.Q. Lobão 151).

FIGURE 12. Distribution of Eugenia guanabarina.