Myrcia eugenioides Cambessèdes (1832

Santos, Matheus F., 2025, Taxonomic monograph of Myrcia sect. Eugeniopsis (Myrciinae, Myrteae, Myrtaceae), an endemic clade of Eastern South America, Phytotaxa 703 (1), pp. 1-100 : 24-26

3. Myrcia eugenioides Cambessèdes (1832 –1833: 302) ( Figures 11 , 12 ).

≡ Calyptromyrcia eugenioides (Cambess.) O. Berg (1855 –1856: 34). Marlierea eugenioides (Cambess.) D. Legrand (1958: 265) . Type: — Brazil, Rio de Janeiro, 1816–1821 (fl.), Saint-Hilaire A1-389 (lectotype P! [P00161444] designated by Santos et al. 2019; isolectotypes MPU! [MPU011021] [image], P! [P00161445], P! [P00161446]).

= Calyptromyrcia eugenioides var. glabra O. Berg (1857 –1859: 56). Type: — Brazil, Rio de Janeiro, Jurujuba bay, 1837 (fl.), Gardner 758 (neotype K! [K000330592] designated by Santos et al. 2019; isoneotypes E! [E00504684] [image], E! [E00504685] [image], G!, K! [K000330593], K! [K000342676], NY! [NY00405395] [image], P! [P00547506]).

= Aulomyrcia lineata O. Berg (1857 –1859: 68). Myrcia lineata (O.Berg) Niedenzu (1893: 76) . Type: — Brazil, Rio de Janeiro, mun. Rio de Janeiro, “Habitat in silvis montis prope Praya dos Flamingos, Sebastianopoli, prov. Rio de Janeiro ” (in the protologue), September 18?? (fl.), Beyrich s.n. (syntype B†). Neotype: — Brazil, Rio de Janeiro, 1844 (fl.), Widgren 787 (BR!, designated by Santos et al. 2019).

Description:— Tree, 3 to 9 m high. Trichome reddish, simple or dibrachiate, 0.05–0.3 mm. Twig when young flattened and distally sulcate, tomentose, when mature reddish to greyish (when dry), cylindrical, glabrous, cork slightly cracked; branching monopodial, internode 2.0– 6.5 cm, node slender; cataphylls absent; buds pubescent. Leaf concolorous, chartaceous, blade 5.5–16.8 × 2.3–7.5 cm, elliptic or oblong, apex acuminate to obtuse, base cuneate, sometimes attenuate, margin plane, secondary veins 4–9 mm apart, held at an angle of 70–80° relative to the midvein, marginal vein 1.0–3.0 mm from the margin, tertiary veins conspicuous to barely conspicuous in both surfaces, areoles 0.5–1.0 mm, pellucid dots conspicuous in the abaxial surface, 6–8 per mm 2; adaxial surface glabrous, secondary veins flat to raised, usually thin; abaxial surface glabrous (rarely subglabrate), secondary veins flat to raised; petiole 6–9 × 2-3 mm, canaliculate, glabrous. Inflorescence 5.0–20.5 × 2.5–17.0 cm, 30–90 flowers, axillar at the terminal or subterminal nodes of the SGU (central bud usually not developed), one or two inflorescence per axillary bud (rarely a short internode with a pair of lateral inflorescences and an abortive central bud), inflorescence pherophyll persistent or deciduous, opposite or subopposite branching, three to five branching per node, rachis puberulent to glabrous, first internode of central rachis 1–3 mm wide; bracts 2.6–3.2 × 1.2–1.6 mm, deciduous, elliptic or ovate, plane or concave, apex acute to obtuse, base cuneate, externally puberulent to glabrous, internally glabrous; bracteoles 2.0–5.0 × 2.0–5.0 mm, deciduous, ovate to widely ovate, concave, apex acuminate to acute, base truncate, both surfaces puberulent. Flower bud ca. 4.0 × 3.0 mm, clavate with obconic base, corolla hidden or barely apparent before anthesis; hypanthium 1.2–1.8 mm extending above the summit of the ovary, not tearing at anthesis or with a small vertical rip (but not tearing staminal ring), externally puberulent to glabrous, pellucid dots conspicuous; calyx 4–5–merous, lobes 0.4–2.5 × 1.0– 2.5 mm, not fused, deciduous parallel to the hypanthium ring, depressed ovate to widely depressed ovate, concave, apex rounded, externally puberulent to glabrous, internally pubescent to puberulent; corolla 4–5–merous, petals cream to white, 1.2–2.0 × 1.6–2.4 mm, widely depressed ovate, very widely ovate or very widely obovate, plane or concave, apex rounded, both surfaces puberulent to glabrous; staminal ring 0.2–0.4 mm wide, puberulent, stamens 35–80, filament 2.4–4.8 mm long, anther 0.24–0.40 × 0.24–0.48 mm, gland at the apex; ovary 0.8–1.0 × 0.8–1.0 mm, obconic, style ca. 7.2 mm long, subglabrate to glabrous, stigma punctiform. Fruit not seen.

Distribution and Habitat: — Myrcia eugenioides is recorded within the Atlantic Forest domain, with an atypical record in a semideciduous forest in the Cerrado domain (Felício dos Santos municipality) ( Figure 12 ). Mostly records come from the central region of Rio de Janeiro state, with two additional records from Bahia and Alagoas state. The species inhabits rain forest or restinga vegetation (either open or forested), and occasionally occurs in flooded or semideciduous forests. Elevations range from 300 to 1,320 meters.

Phenology: —The species flowers from June to December. Fruits have been recorded (immature) in February and October.

Conservation Status: —The species has an Extent of Occurrence of ca. 276,284 km 2 (threshold of Least Concern) and a Small Area of occupancy (40 km 2, threshold of Endangered) (sensu IUCN 2022). Myrcia eugenioides is known from less than 10 localities, with only two of these occurring within Conservation Units. Available data does not allow the estimation of population size and fluctuation, but the Atlantic Forest currently has only 24% of its original extension, and many areas are small, disturbed, and disconnected fragments (Fundação SOS Mata Atlântica & INPE 2022). Based on this scenario, we preliminarily assess the species as Vulnerable (VU, criteria B2a, bii, biii; IUCN 2022).

Taxonomy: — Myrcia eugenioides is characterized by thick and reddish to greyish young branches, monopodial branching, large elliptic to oblong leaves with acuminate to obtuse apex and usually glabrous with thin secondary veins on the adaxial surface, inflorescences arising from multiple nodes along the SGU, and flower bud with obconic base. The species resembles Myrcia gaudichaudiana (for instance Braga 4554, Kuhlmann s.n. [RB 111588]), but can be distinguished by its branch, the large leaves with thin secondary veins and the shape of the flower bud. Specimens from Felício dos Santos municipality exhibit the typical morphological characteristics of the species, despite the unique occurrence in the Cerrado domain.

Illustrations and images in previous works: — Fernandes et al. (2020).

Additional specimens examined: — BRAZIL. Unknown province /state, no date(fl.), F . Sellow s.n. ( LE). Alagoas: Mun. Boca da Mata , 29 October 1980 (fl.), G. L . Esteves 611 ( HUEFS, RB). Bahia: Mun. Cairú, 13 November 2003 (fl.), J. L . Paixão 309 ( BHCB, CEPEC). Minas Gerais: unknown municipality, 13 February 1972 (fr.), W. R . Anderson 35932 ( NY, RB). Mun. Felício dos Santos, 8 October 2004 (fr.), P. L . Viana 1890 ( BHCB); ibidem, 29 August 2008 (fl.), P. L . Viana 3705 ( BHCB). Rio de Janeiro: unknown municipality, no date (fl.), J . Miers s.n. ( P00547504 ); no date (fl.), J . Miers s.n. ( P00547505 ). Mun. Niterói , no date (fl.), J . Miers 3697 ( K); ibidem, 25 November 2018 (fl.), T . Fernandes 422 ( RB). Mun. Rio de Janeiro, 2 September 1943 (fl.), J. G . Kuhlmann s.n. ( NY, RB111588 ); ibidem, 18 December 1997 (fl.), J. M. A . Braga 4554 ( RB); ibidem, 1945 (st.), O. Machado s.n. ( RB75807 ); ibidem, 5 May 1947 (st.), O . Machado s.n. ( RB75144 ). Mun. Saquarema , 23 April 1991 (st.), C . Farney 3214 ( ESA, RB). Mun. Teresópolis, 26 June 2007 (fl.), M . Nadruz 1832 ( RB) .

Figures

FIGURE 11. Representative specimens of Myrcia sect. Eugeniopsis: Myrcia eugenioides (J.G.Kuhlmann s.n. [RB111588]).

FIGURE 12. Distribution of Myrcia eugenioides (triangles) and Myrcia reitzii (circles). Solid lines represent the boundaries of South American countries and Brazilian states. The grayscale reflects elevation.