Myrceugenia bananalensis Gomes-Bezerra & Landrum, 2014

Myrceugenia bananalensis Gomes-Bezerra & Landrum View in CoL sp. nov.

Type:– Distrito Federal: Brasília, margem esquerda do Córrego Bananal na margem da BR-020 , 15 o 43’51”S, 47 o 54’46”, 1011 m, fl., K.M. Gomes-Bezerra & J.E.Q. Faria 31 (Holotype UB GoogleMaps , Isotypes ASU , K , RB , HUFSJ ). Figure 1 View FIGURE 1 .

Similar to M. glaucescens but differing in having a mixture of simple and asymmetrically dibrachiate trichomes (versus mainly symmetrically dibrachiate); young twigs with spreading hairs (versus appressed hairs), peduncle ca. 0.3 mm wide (versus 0.5–1 mm wide), stamen number 126–130 (versus 140–250).

Small tree 2–4 m high, well-branched; trichomes simple and dibrachiate (anvil-shaped); trunk with rough and dark-brown bark; branches when young and twigs covered by scattered pubescence; old branches glabrescent with rhytidome grayish-brown and finely fissured. Blades elliptic to rarely obovate, chartaceous to coriaceous, discolorous, 4–7.5 × 2.7–4 cm, 1.9–2.6 times longer than wide; apex acute to short-acuminate; base acute to obtuse; margin slightly revolute; adaxial surface glabrescent; abaxial surface sericeous with concentration of brown trichomes on the midvein; stomata with crests; midvein adaxially canaliculate; glandular dots opaque in young and old leaves; petioles channeled, glabrescent, about 0.2–0.5 cm length. Venation brochidodromous. Flowers axillary, rarely superimposed in pairs in the axils of the leaves or in dichasia; peduncles flattened, 1.5–3.5 cm long, c. 0.3 mm wide, glabrescent and glandular; bracts elliptic, concave, pubescent, deciduous before anthesis, c. 0.5–1.0 × 0.3–0.5 mm; bracteoles lanceolate, c. 1.3– 1.5 × 0.5–0.7 mm, slightly concave, pubescent externally, with translucid glandular dots and basal colleters. Flower bud obconic, 2–4 mm long, hypanthium sericeous, the trichomes grayish; calyx-lobes triangular to ovate, 2.0–2.5 × 0.6–0.8 mm, with translucid glands, externally glabrescent and internally pubescent; petals orbicular, 3.6–3.9 × 3.5– 3.7 mm, concave, glabrous, with ciliate margins and translucid glands; apex rounded; stamens 126–130, 3.5–5.0 mm long, with translucid glands; anthers 0.3–0.5 mm long; style 4.0–6.0 mm long, glandular, sericeous at the base; ovary 3–4-locular, with 4–9 basal ovules per locule; placenta protruding. Fruit globose, 0.5–0.9 cm, sparsely sericeous, vinaceous when mature with translucid glands, calyx-lobes erect; seeds 6–8; seed coat membranaceous, soft, brown and opaque; embryo densely glandular.

Phenology: —Flowers September–October, fruits December.

Etymology: —The specific epithet alludes to the occurrence of this species on the margins of the Bananal stream.

Distribution, Habitat: — Myrceugenia bananalensis is found only in gallery forest along the margin of the Bananal stream in Distrito Federal. Gallery forests are a phytophysiognomy of the Cerrado Biome defined as forest vegetation that runs along small rivers and streams of the plateaus of Central Brazil ( Ribeiro & Walter 2008). Figure 2 View FIGURE 2 .

Conservation Status: —This species is known from only one population on the Bananal stream margins in the Parque Nacional de Brasília, a Brazilian federal conservation unit. However its restricted occurrence area, probably no more than 10 km 2, suggests its inclusion in IUCN red list species (2001) as critically endangered (CR), according to criteria B.2.a.b and C. Another cause for concern is the Paranoá Lake built in the 1950’s and 1960’s to provide a water supply to Brasília. This may have taken a wide portion of the natural occurrence area of the species and became a major barrier for natural dispersal of species.

Material examined: Brazil. Distrito Federal: Brasília, córrego Bananal, próximo ao parque Água Mineral de Brasília , 23 September 2011, fl., J.E. Paula 3806A ( UB) ; ibid.; margem esquerda do Córrego Bananal na margem da BR-020 , 15 o 43’51”S, 47 o 54’46”, 1011 m elev., 4 October 2011, fl., K.M. Gomes-Bezerra & J.E.Q. Faria 33 ( ASU, UB) GoogleMaps ; ibid., K.M. Gomes-Bezerra & J.E.Q. Faria 34 ( HUEFS, K, NY, UB) ; ibid., J.E.Q. Faria et al. 1986 ( BHCB, CEN, HUEG, UB) ; margem esquerda do Córrego Bananal na margem da BR-020 , 15 o 43’46”S, 47 o 54’33”, 1013 m elev., 2 December 2011, fr., J.E.Q. Faria & M.R.V. Zanatta 2196 ( ASU, IBGE, RB, UB) GoogleMaps ; ibid., 12 December 2011, fr., K.M. Gomes-Bezerra & J.E.Q. Faria 36 ( ASU, CEN, MBM, UB) .

Scanning Electron Microscopy:— Myrceugenia bananalensis has hypostomatic leaves, with platelet shaped epicuticular wax on both sides ( Koch et al. 2009); also dibrachiate “anvil-shaped” trichomes ( Payne 1978) present only on the abaxial surface, the shorter arm 45–55 µm, the longer 50–90 µm. Bracteoles possess “standard”-S type colleters ( Lersten 1974) in the basal portion, 177–257 µm long. Pollen grains are triangular in polar view, oblatespheroidal (P/E=0.9) in equatorial view ( Erdtman 1952) and irregularly parasyncolpate ( Barth & Barbosa 1972). Pollen grain surface is verrucous with warts varying from 0.25–1 µm diam. Figure 3 View FIGURE 3 .

Leaf venation:—Venation is pinnate-brochidodromous with veins to fifth order; there are 12–15 pairs of secondary veins, inconspicuous on the adaxial surface with angles of divergence at 55–65˚ and closing with the secondary intramarginal vein at an obtuse angle, exmedial and admedial intersecondary veins are branched; tertiary veins are alternate, percurrent; veinlets are dendritically branched; areoles are polygonal, well developed, 0.4–0.7 mm, 4–7 sides, 130–160/cm 2; intramarginal vein is 0.5–1.2 mm from the edge; ultimate marginal venation is looped from the base ( Ellis et al. 2009). Figure 4 View FIGURE 4 .