Eugenia rufula Bunger, E. Barretto & Sobral 2024, sp. nov.
Creators: name: Bünger, Mariana De Oliveira
name: Barretto, Eduardo H. P.
name: Sobral, Marcos
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Myrtales
Myrtaceae
Eugenia
Eugenia rufula

description: Eugenia rufula Bünger, E.Barretto & Sobral, sp. nov.
Type:— BRAZIL. São Paulo: São Paulo, Marsilac, próximo ao Sítio Maravilha, 800 m elev., -23.95654, -46.72147 7 October 2014, E.H.P. Barretto, L. Granato, F.F. Paschalicchio & O.S. Anjos Neto 315 (holotype PMSP!; isotypes EAC!, HUFSJ!). Figures 1–4.
Diagnosis:—This species is morphologically related to Eugenia expansa Spring ex Martius (1837: 84; type image BR 522979), from which it differs by the rufescent indumentum in twigs and young leaves which mostly disappear in older twigs and leaves (versus indumentum light brown, cupreous or greyish on young parts which usually persist in old twigs and leaves in E. expansa), leaves with petioles 7–10 mm (vs. 4–6 mm), and blades with 12–16 lateral veins (vs. 18–30); flower buds uniformly and densely covered with indumentum (vs. flower buds glabrous or with ovaries markedly more pilose than the sepals), sepals in slighlty unequal pairs, these 1.3–1.4 times longer than wide (vs. four sepals equal, these 2.3–2.5 times longer than wide).
Description:—Trees 8–10 m high. Bark moderately rugose, greyish, longitudinally striate, these stripes occasionally detaching. Twigs semiterete, densely covered by simple ascendent rufescent trichomes 0.5–1 mm, these mostly scattered or absent in older parts, then the twigs greyish, slightly longitudinally striate and with occasional dark glands to 0.2 mm in diameter; internodes 12–30 × 1–2 mm, those with only vegetative growing a little shorter in length than those bearing flowers. Leaves opposite, densely covered by trichomes as the twigs when young which turn very scattered in adult ones; petioles 7–10 × 1–1.1 mm, semiterete, adaxially markedly canaliculate, rugose when dry, densely pilose in young leaves, the indumentum either persisting or vanishing completely in adult leaves; blades narrowly elliptic, 70–120 × 26–33 mm, 3–3.6 times longer than wide, dull green on both faces, slightly discolorous when dry, the adaxial side usually glabrous, the abaxial side glabrous or with remnants of the dense juvenile indumentum usually perceptible along the midvein and in irregular patches along the surface; glandular dots irregularly distributed along the surface, smaller than 0.1 mm in diameter and 6–10/ mm², visible when backlit and occasionally perceptible and darker than the surface on the abaxial side; base acute or slighlty cuneate, somewhat deccurent along the petioles; apex acuminate in 10–15 mm; midvein adaxially impressed, sometimes becoming plane distally, and abaxially visibly raised; lateral veins 12–16 at each side, leaving the midvein at angles 60–70°, perceptible and very softly raised on both sides, a little more so abaxially; intramarginal veins two, the inner one 1.5–2 mm from the margin, perceptible since the very base of the blades, the outer one scarcely visible, ca. 0.2 mm from the margin; margin slightly revolute and with a light green girdle to 0.2 mm wide. Inflorescences auxotelic, i. e., giving origin to simultaneous vegetative growth at the apex of the twig from which emerge usually four flowers; bracts ovate, carenate, to 4 × 2 mm, glandular, adaxially glabrous and pilose abaxially, deciduous at anthesis; pedicels 7–24 × 0.6–1 mm, densely covered with rufescent simple trichomes to 1 mm; bracteoles cordiform, slightly carenate, glandulose, persisting after anthesis, 4–11 × 3–6.5 mm, adaxially glabrous or with scattered trichomes, abaxially densely pilose as the pedicels; flower buds obpyriform or ellipsoid, 9–12 mm long × 4–8 mm in diameter, densely and uniformly covered with rufescent trichomes 0.5–1 mm, the ovary usually concealed by the bracteoles; hypanthium obconic, 3–4 mm long × 5–6 mm in diameter; sepals four, densely pilose on both sides but the indumentum very scarce or absent along the proximal portion of the adaxial side, in two slightly unequal pairs, the outer one ovate, 8–10 × 6–7 mm, the inner one elliptic-ovate, 8–9 × 5–6 mm, patent at anthesis, the very base apparently slightly tearing longitudinally for about 1 mm; petals four, rounded or oblate, 6–8 × 6–8 mm, glandulose, glabrous or with very scattered trichomes adaxially and cilia to 0.3 mm; stamens with filaments 4.5–8 mm, the anthers subglobose, 0.7–0.8 × 0.6–0.7 mm, with one apical gland; staminal ring 5–6 mm in diameter, 2 mm thick, with simple rufescent or grey trichomes to 0.2 mm; calyx tube perceptible, to 1 mm deep, pilose as the staminal ring; style glabrous, to 6 mm, the style slightly swollen, papillose; ovary externally smooth, with two internally glabrous locules and 7–8 ovules per locule. Fruits ellipsoid, to 22 mm long × 15 mm in diameter, reddish when ripe, with moderately sweet taste (E. Barretto, pers. obs.) sparsely puberulent, crowned by the sepals; one-seeded, the seed ellipsoid, to 11 mm long × 8 mm in diameter, the testa whitish, seed with hypocotyl and cotyledons fused and indistinguishable.
Distribution, habitat and phenology:—This species is presently known only from the locality of Marsilac, in the municipality of São Paulo (Figure 4), at the eastern portion of the southeastern Brazilian state of São Paulo, where it was collected in montane rainforests about 800 m elev. Flowers were collected in October, and fruits in December and May.
Etymology:—The epiteth is allusive to the reddish coloration of the branches, young leaves and flowers of the species.
Conservation status:— Eugenia rufula is presently known from four collections, all of them from Marsilac, a district of the municipality of São Paulo. The collection site is a well-preserved remnant of montane rainforest in the southern portion of São Paulo, the largest city in South America. The fact of an undescribed tree species being discovered in the area of one of the largest metropolises of the world is an exceptional situation that must be highlighted, since it is very illustrative of the incomplete botanical knowledge even of intensely populated areas in Brazil. There are presently known five individuals from the species in the collection site (E. Barretto, pers. obs.); nevertheless, since the forest remnant where Eugenia rufula was collected was not intensely surveyed as to gather specific data on the distribution of the species, it is here preliminarly assessed as DD (Data Deficient). According to IUCN (2022) guidelines, this category is suggested “when there is inadequate information to make a direct, or indirect, assessment of its risk of extinction based on its distribution and/or population status” (IUCN 2022: 10), which is the present case.
Affinities:—This species is morphologically close to the southeastern Brazilian Eugenia expansa, with which it is compared in the diagnosis (for an additional description of E. expansa, see Bünger et al. 2020: 105). Regarding its sectional placement, the auxotelic inflorescences and the large, persisting bracteoles, suggest its assignment to Eugenia section Phyllocalyx Niedenzu (1893: 82), according to the classification proposed by Mazine et al. (2016). Despite its sectional placement, Eugenia rufula is strikingly vegetatively alike to some collections of Eugenia longipetiolata Mattos (1968: 162; specimen: Bünger et al. 626, BHCB!, K!), a species belonging to Eugenia section Speciosae Bünger & Mazine (in Bünger et al. 2016: 75), although the morphology of the bracteoles—one of the diagnostic features distinguishing these sections—is visibly distinct in both species, since in E. longipetiolata they are linear and up to 20 × 1.5 mm while in E. rufula they are cordiform and up to 11 × 6.5 mm.
Paratypes:— BRAZIL. São Paulo: São Paulo, Marsilac, 19 May 2015 (fr.), E.H.P. Barretto, F.F. Paschalicchio, L. Granato & O.S. Anjos Neto 471 (EAC!, PMSP!); ibidem, 13 December 2023 (fr.), E.H.P. Barretto 3450 (PMSP!); ibidem, 13 December 2023 (fr.), E.H.P. Barretto 3451 (PMSP!).
description: Published as part of Bünger, Mariana De Oliveira, Barretto, Eduardo H. P. & Sobral, Marcos, 2024, Eugenia rufula (Myrtaceae), a new species from São Paulo, Brazil, pp. 106-110 in Phytotaxa 663 (2) on pages 106-109, DOI: 10.11646/phytotaxa.663.2.7, http://zenodo.org/record/14515850