Eugenia saxatilis Sobral & Bünger, 2021

Sobral, Marcos, Bünger, Mariana O., Azevedo, Luísa O. & De Paula, Luiza F. A., 2021, Eugenia saxatilis (Myrtaceae), a new species from Minas Gerais, Brazil, Phytotaxa 522 (2), pp. 157-160 : 157-160

Eugenia saxatilis Sobral & Bünger , sp. nov.

Type:— BRAZIL. Minas Gerais: Teófilo Otoni, Pedra São Francisco, fazenda de Cássio Adinny , 17°51’22” S, 41°15’39” W, 28 January 2014, fl., L.O. Azevedo, L.A.F. de Paula, R.L. Fernandes & J.R. Stehmann 137 (holotype BHCB! , isotype RB!) . Figures 1–2 .

Diagnosis:—This species is morphologically related to Eugenia repanda O. Berg (1857 –1859: 304; type image W 0047760), but differs by its petioles 0.5–1.5 mm, to 3–4% of the blade’s length (versus petioles 2–4 mm, 7–12% of the blade’s length in E. repanda ), inflorescences without developed axis (vs. axis 1–10 mm), with one to two flowers (vs. up to eight flowers), pedicels 4–4.5 × 0.2–0.3 mm, 15–20 times longer than wide (vs. 1–2 × 0.3–0.4 mm 3–5 times longer than wide), elliptic flower buds to 3 × 1.2 mm (vs. globose, to 3 × 3 mm), triangular bracteoles to 0.6–0.8 × 0.5 mm (vs. rounded, to 0.8–1 × 1 mm), ellipsoid fruits (vs. globose) and seeds with two separate cotyledons (vs. cotyledons fused).

Description:—Shrub 0.6– 2 m. Twigs with erect simple light brown or yellowish trichomes 0.3–0.5 mm, these falling with age and then becoming grey or brown and longitudinally striate; base of the twigs frequently with persisting triangular cataphylls to 1 × 0.3–0.4 mm. Leaves with petioles 0.5–1.5 × 0.2–0.5 mm, pilose as the twigs, adaxially applanate; blades ovate or elliptic, 14–35 × 8–12 mm, 1.7–3 times longer than wide, when young covered with simple trichomes as the twigs on both sides, when adult with the trichomes absent or restricted to the midvein at the adaxial side and scattered along the surface at the abaxial side, discolorous when dry, dark green and occasionally shining adaxially, lighter and dull abaxially; base obtuse; apex acute or occasionally widely acuminate in 2–3 mm; glandular dots evident and sometimes raised on both sides, 30 to 40/mm², of several sizes, the larger ones about 0.05 mm in diameter, these more scattered than the smaller ones; midvein plane or finely sulcate adaxially and raised abaxially; lateral veins 6 to 10 at each side, leaving the midvein at angles 45–60°, moderately raised on both sides, occasionally the first or second vein extending along nearly all the extent of the blade and forming the marginal vein; marginal vein continuous, to 1 mm from the margin, this sometimes with cilia to 0.2 mm. Inflorescences with solitary flowers or more frequently two flowers, these axillary or arising from ramiflorous brachyblasts, on both cases the axis not visible; bracts widely ovate, to 0.3 × 0.2 mm, pilose as the twigs, usually deciduous before anthesis; pedicels 4–4.5 × 0.2–0.3 mm, with simple hispid trichomes to 0.2 mm; bracteoles triangular, persisting after anthesis, 0.6–0.8 × 0.5 mm, with trichomes to 0.3 mm; flower buds elliptic, to 3 × 1.2 mm, the hypanthium and the calyx lobes with scattered trichomes to 0.3 mm; sepals four, markedly glandulose, adaxially glabrous, in two slightly unequal pairs, the inner one acute, to 0.8 × 0.6 mm, the outer one elliptic or widely elliptic, to 1 × 0.7 mm; petals oblong or oblong–ovate, glabrous or with scattered trichomes, 3.5–4 × 0.7–0.8 mm; stamens 25 to 35, the filaments 3–3.5 mm, the anthers elliptic, to 0.3 × 0.2 mm, with one apical gland, this apparently sometimes deciduous; staminal ring to 1 mm in diameter, with scattered trichomes; calyx tube to 0.5 mm deep or absent; style glabrous, to 5 mm, the stigma slightly capitate and papillose; ovary with two internally glabrous locules and 3 ovules per locule. Fruits ellipsoid, 7–15 × 5–8 mm, black when ripe; seed one, ellipsoid, the testa easily detachable from the embryo and adherent to the endocarp; embryo with two plano-convex cotyledons and no visible hypocotyl.

Distribution, habitat and phenology:—This species is known from seasonal forests, belonging to the Atlantic Forest domain, on isolated granite and/or gneiss rock outcrops (“pães de açúcar”, “inselbergen” or “sugar loaves”) about 560 m elev. in the eastern portion of the state of Minas Gerais; these outcrops have been considered as local hotspots of plant diversity ( de Paula et al. 2020). More specifically, E. saxatilis was found only on the so-called “thicket” or “scrub” vegetation type ( Rizzini 1997), which is a transition zone between the rock outcrop and the seasonal forests that border the inselberg. Flowers and fruits were collected in December and January.

Conservation:— Eugenia saxatilis is presently known from four collections; three recent georeferenced records at the São Francisco inselberg and one made in 1961 bearing only the information “between Teófilo Otoni and Nanuque”, two municipalities about 50 km apart. These municipalities encompass together an area of 4,760 km ² ( IBGE 2021), in which there are 999 plant records ( INCT 2021), resulting in a very scarce sampling effort of 0.2 collection/km², if considered the minimal value proposed by Campbell (1989) of one collection/km² for tropical countries; considering this, the present evaluation may be altered significantly when this region becomes better botanically explored. The georeferenced specimens allow estimating via GeoCat (2020) an Extent of Occurrence (EOO; IUCN 2012: 11) for this species of 0.005 km ², a very small area which would point to a Critically Endangered (CR) status (GeoCat 2020, IUCN 2012). Furthermore, inselbergs are significantly threatened by mining, quarrying, invasion of exotic plants, altered and more frequent fire regimes, cattle and goat herding and changing in the surrounding land use mainly due to farming ( Porembski et al. 2016). Thus, the natural vegetation in these ecosystems faces increasing risks of extinction. Nevertheless, although the species have an apparently small area and occur in fragmented habitats ( IUCN 2012: 17) there are no additional information regarding population decline or extreme populational fluctuations in order to adequately fulfill IUCN criteria ( IUCN 2012), and consequently for now we score E. saxatilis as DD (Data Deficient; see IUCN 2019: 78).

Affinities:—This species is morphologically close to Eugenia repanda , a species occurring from Bolivia to Uruguay ( Govaerts et al. 2021); considering its reduced inflorescence structure it probably belongs to section Umbellatae O. Berg (1855 –1856: 204), according to the sectional classification proposed by Mazine et al. (2016: 231).

Etymology:—The epithet is derived from the Latin word for rock-dwelling, the typical habitat of the species.

Paratypes:— BRAZIL. Minas Gerais: Teófilo Otoni, fazenda de Cássio Adinny , 17°51’23” S, 41°15’44” W, 28 January 2014, fl., L.A.F. de Paula, L.O. Azevedo, & R.L. Fernandes 1094 ( BHCB!, RB!) ; idem, Pedra São Francisco, fazenda de Cássio Adinny , 17°51’22” S, 41°15’39” W, 28 January 2014, fr., L.O. Azevedo, L.A.F. de Paula, R.L. Fernandes & J.R. Stehmann 131 ( BHCB!, RB!) ; idem, entre Teófilo Otoni e Nanuque , 11 December 1962, fl., J.R. Mattos & H. Bicalho 11051 ( HAS!, HUFSJ!, SP) .

Figures

FIGURE 1. Eugenia saxatilis. Isotype at RB.

FIGURE 2. Eugenia saxatilis. Upper left: flowers (from Azevedo 137; photo J.R. Stehmann); right: ripe fruit (from Azevedo 131; photo L. Azevedo); lower left: São Francisco inselberg (photo L. de Paula).