Eugenia lavradensis Tuler & Sobral 2024, sp. nov.
Creators: name: Tuler, Amélia Carlos
name: Sobral, Marcos
name: Amorim, Gabriela
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Myrtales
Myrtaceae
Eugenia
Eugenia lavradensis

description: Eugenia lavradensis Tuler & Sobral, sp. nov.
Type:— BRAZIL. Roraima: Boa Vista, Campus UFRR, Cauamé, 25 January 2011, J.A. Menezes, A.S. Flores & E.C. Medeiros 1 (holotype MIRR!, isotype HUFSJ 11003!). Figure 1.
Diagnosis:—This species is morphologically related to Eugenia mcvaughii Steyermark & Lasser (1981: 25), from which it is distinguished by its erect flowers (vs. pendulous in E. mcvaughii), with pedicels up to 15 mm (vs. pedicels 15–40 mm), white trichomes (vs. mahogany-colored) and pubescent, globose fruits to 20 mm in diameter, red when ripe (vs. fruits glabrous, oblate, 20 × 25–50 mm, yellow when ripe).
Description:—Shrub to treelet 2– 5 m. Twigs terete, with simple white trichomes 0.3–0.5 mm, these falling with age. Leaves with petioles 2.2–4 × 1–1.8 mm, adaxially sulcate, glabrous or with sparse trichomes like the twigs; blades 50–92 × 26–32 mm, 1.7–3.2 times longer than wide, elliptic, narrowly elliptic to ovate, base cuneate, apex acute or acuminate in 5–10 mm, discolorous when dry, dull green and glabrous or with scattered simple trichomes adaxially, light green and with simple erect whitish trichomes to 0.3 mm abaxially, these usually persisting in adult leaves, perceptible at touch but more easily viewed under lenses; glandular dots about 15/mm², smaller than 0.1 mm in diameter, inconspicuous on both surfaces or sometimes conspicuous adaxially, especially when backlit; midvein finely impressed adaxially and moderately raised abaxially, lateral veins 10 to 15 at each side, leaving the midvein at angles about 60° and finely raised on both sides, more so abaxially, secondary lateral veins visible and about the same gauge of the main lateral ones, marginal veins often one, 1–2 mm from the slightly revolute margin, or sometimes a second marginal vein to 0.2 mm of the margin, both usually arched, in loops formed by the converging lateral veins, in some blades the one or two proximal veins extend themselves along two thirds or more of the blade’s length and then forming the marginal veins along this extent. Inflorescence axillary, fasciculiform, with 2–4 flowers, the main axis 1–1.5 × 1 mm, concealed by narrowly elliptic bracts to 1 × 0.5 mm, these densely covered by white trichomes to 0.3 mm; pedicels 5–15 × 0.3–0.4 mm, with erect or ascending white trichomes as the twigs; bracteoles ovate and markedly concave, 2 × 1–1.2 mm, glabrous and glandulose adaxially and densely pilose abaxially, deciduous at anthesis, with three or four linear whitish persisting colleters 3–4 × 0.4 mm at its axil; flower buds ellipsoid or obovoid, to 10 × 0.8 mm, with whitish trichomes, the hypanthium 1.5–2 mm and more densely pilose than the sepals, these four, pilose on both sides but less so adaxially, in two unequal pairs, the outer pair widely elliptic, 3–3.5 × 3 mm, the inner one shortly oblong, 4.5–5 × 3.5–4 mm, reflexed at anthesis; petals four, rounded or elliptic, 7–8 × 7 mm, nearly glabrous except for cilia to 0.2 mm; stamens not counted, the filaments to 6 mm, the anthers globose, to 0.4 mm in diameter, with one interconnectival gland; staminal ring subquadrate, 2.5–3 mm in diameter, with scattered white trichomes to 0.1 mm; calyx tube absent; stigma to 8 mm, glabrous, the stigma slightly capitate and papillose, darker than the style; ovary with two internally glabrous locules, each with 4–5 ovules. Fruits globose, to 12 mm in diameter, densely white-pubescent when young, with persistent pubescence at base and right below the sepals, red when ripe; seed one, reniform, to c. 7 mm, drying brown, the testa easily detachable, embryo with no visible hypocotyl and two cotyledons, these partially fused and with a visible but shallow furrow between them about half their extent, not easily separable.
Distribution, habitat, and conservation status:— Eugenia lavradensis is known from the Brazilian states of Maranhão and Roraima; in Maranhão it was collected in upland forests with sandy soils (“terra firme”, Amazonian physiognomy that is not flooded throughout the year—see Lima 1956) and in Roraima it occurs along dry sandy savannas in the municipalities of Boa Vista, in the margin of the Cauamé River, and Caracaraí, in the vicinity of the Branco River.
The savanna of Roraima, denominated locally as “campos do rio Branco” or “lavrado”, is the Brazilian portion of the largest continuous area of savanna in northern Amazon, comprising about 43,000 km ² or ca. 19% of the state’s area (Barbosa & Campos, 2011). This ecoregion contains a diverse array of phytophysionomies forming a mosaic of non-forest (open areas) and forest ecosystems that generates a great heterogeneity of habitats which is reflected in its high plant diversity (Barbosa et al. 2007).
Despite its important ecological context, this entire region is under threat from the expansion of agribusiness and still does not have any unit of full protection conservation or sustainable use (Pinto et al., 2014).
In Caracaraí, the proposal for the development of the Bem Querer hydroelectric plant in Rio Branco is underway and would flood approximately 150 km long, including the area of occurrence of the species (Souza et al. 2022).
Based on three populations in as many localities of occurrence, Eugenia lavradensis has an extent of occurrence (EOO) = 249,532.155 km ² and an area of occupancy (AOO) = 16.000 km ². Consequently, its conservation status should be categorized as EN (endangered) since it fulfills conservation criteria B2ab(i,ii,iii,iv). In the case of Eugenia lavradensis being (a) known to exist at no more than three locations and (b) the continuing decline inferred from the (i) extent of occurrence, (ii) area of occupancy and (iii) area, extent and/or quality of habitat (IUCN 2023).
Affinities:— Eugenia lavradensis is morphologically related with the Venezuelan Eugenia mcvaughii, with which it is compared in the diagnosis. Regarding its sectional placement, considering its fasciculiform inflorescences it may be assigned to Eugenia section Umbellatae O. Berg (1855 –1856: 204), according to the sectional proposition of Mazine et al. (2016, 2018).
Phenology:—Specimens with flowers were collected in January and April and with fruits in April and May.
Etymology:—The epithet is derived from “lavrado”, one of the local names for the Roraima savanna, where two individuals of the species has been collected.
Paratypes:— BRAZIL. Roraima: Boa Vista, Campus UFRR, Cauamé, área de mata ciliar do Rio Cauamé, 25 January 2011, fl., J.A. Menezes, A.S. Flores & E.C. Medeiros 10 (MIRR!); idem, RR-321, após a ponte do Igarapé do Carrapato, 2°78’01” N, 60°6’61” W, 11 May 2012, fr., R.O. Perdiz 1321 (HUFSJ!, MIRR!); idem, Conjunto Bella Vista, propriedade de M.C.O.P Silveira, sítio Toca da Loba, 2°87’01” N, 60°6’61” W, 11 May 2012, fr., R.O. Perdiz 1325 (MIRR!); Caracaraí, médio Rio Branco, corredeiras do Bem Querer, 26 April 2014, fr., R.C.P. Souza 6 (HUFSJ!, UFRR!). Maranhão: Santa Luzia, Fazenda Agripec (Varig Airlines), 7km W of Buriticupu on BR 222, 11km from entrance along Fazenda road to Rio Pindare where Carajás railroad runs parallel to river, 46 o 24’ W, 4 o 03’ S, 4 April 1983, fl., E.L. Taylor et al. 1143 (MG!).
description: Published as part of Tuler, Amélia Carlos, Sobral, Marcos & Amorim, Gabriela, 2024, Eugenia lavradensis (Myrtaceae), a new species from the Brazilian Amazon, pp. 179-182 in Phytotaxa 634 (2) on pages 179-181, DOI: 10.11646/phytotaxa.634.2.10, http://zenodo.org/record/13878849