Erythroxylum sobraleanum Loiola & L.S. Cordeiro, 2014

Iracema, Maria, Loiola, Ezerra & Cordeiro, Luciana Silva, 2014, Erythroxylum sobraleanum (Erythroxylaceae): A new species from Southeastern Brazil, Phytotaxa 183 (1), pp. 56-60 : 56-59

Erythroxylum sobraleanum Loiola & L.S. Cordeiro , sp. nov. ( Figs. 1 , 2 )

A new species characterized by stipules long-triangular, non-striate, membranaceous, 3-setulose, with margin fimbriolate to entire, leaves membranaceous, flowers at the apex of short shoots, and styles connate 2/3 its length in dolichostylous flowers.

Type:— BRAZIL. Minas Gerais: Bom Jardim de Minas, 1226 m, 02 October 2011, (fl), M. Sobral 14248 (holotype HUFSJ , isotype EAC ).

Shrubs to small trees, 1–2 m tall, sparsely branched. Bark grayish, dotted with small elliptical and yellowish lenticels. Branches more or less distant, spreading, flexuous, strongly differentiated into long and short shoots, these somewhat compressed toward apex, greenish to reddish when young, dotted abundantly with minute lenticels. Cataphylls persistent, distichous (branches or base short shoots) or congested at apex of short shoots (the inferior shorter than superior), similar to foliar stipules when young, but smaller and turning blackish with age, non-striate. Foliar stipules persistent, long-triangular, 6–9 mm long, rounded apex, non-striate, membranaceous, 3–setulose, keels subalate, margin markedly fimbriolate (when young) to entire with age; setae deciduous, lateral setae 0.6–0.8 mm long, presenting colleters, medial setae a litte longer. Leaves persistent, short-petiolate; petioles subterete, 2–3 mm long, canaliculate adaxially; leaf blades elliptic or ovate, 5.2–7.8 × 2.7–3.8 cm, acute to acuminate at base, acute to rounded at apex, margin entire to slightly undulate, membranaceous, slightly discolorous, adaxially dark green, abaxially pale green; the midrib impressed adaxially, prominent abaxially, 9–11 secondary nerves on each side, the veinlets finely reticulate, most evident on lower leaf surface. Buds rounded, 5–6 × 1.3–1.5 mm, greenish white or yellowish green. Pedicels conspicuous, 3–4.5 mm long, somewhat thickened. Flowers 1–2 per node, produced near the apex of new short shoots or new long shoots in axils of leaves or cataphylls, 7–9 mm long. Bracteoles 1, ca. 1 mm long, 1–setulose, keel sub-alate, non-striate, triangular, concave, margin entire. Calyx divided 3/4 its length, lobes long-triangular, 1.2– 1.5 × 0.5–0.8 mm, shorter than the staminal cup. Petals oblong, 3–3.3 × 1–1.2 mm, concave, rounded at the apex, bilobate. Staminal cup 1.2–1.5 mm long, crenulate at margin, shorter than ovary. Brachystylous flowers not seen. Dolichostylous flowers: antesepalous filaments 0.8–1 mm long, antepetalous filaments 1.2–1.5 mm long, anthers oblong, ca. 0.5 × 0.4 mm; ovary oblong, 2–2.2 × 0.8–1 mm, styles connate 2/3 its length, 3–3.5 mm long, stigmas depressed-capitate. Drupe not seen.

Etymology:—The new species honors Marcos Eduardo Guerra Sobral, botanist at the Federal University of São João Del Rei, Brazil, collector of the type specimen. He has also provided invaluable information about the localization of the populations and type vegetation, and sent several field pictures.

Additional specimen examined (paratype):— BRAZIL. Minas Gerais, Rio Preto, UHE de Mello—Ribeirão Santana , 6 October 1996 (fl), R.G. Silveira, F.R. Pires, L.G. Canani, R. Oliveira, C.A.N. Ribeiro s.n. ( CESJ 30636 , EAC 48735 ) .

Distribution and habitat:— Erythroxylum sobraleanum was observed in only two municipalities of south Minas Gerais, near the border with Rio de Janeiro state ( Fig. 3 ). This species grows in the Seasonal semi-deciduous montane forest ( IBGE 2012), at 1226 m elevation, on the Serra da Mantiqueira, with predominantly plutonic rocks (granite) and high grade metamorphics (migmatites, gneiss). This mountain range is extremely important in a geo-environmental sense. Several water sheds that feed important urban centers of southeastern Brazil occur there, as well as important Atlantic Forest fragments ( Benites et al. 2007) which are hotspots of biodiversity ( Myers et al. 2000). The two collections, both with flowers, were gathered in October. The characteristics of the fruits (drupes) are unknown.

Conservation status:—C onsidering that only two samples were collected in the area and that few individuals of Erythroxylum sobraleanum has been observed, this species is considered rare. However, based on IUCN (2001) criteria, the conservation status of this species is Data Deficient (DD).

Discussion:— Erythroxylum sobraleanum superficially resembles E. oxypetalum , a rare species also of sect. Archerythroxylum, in its general branching appearance and leaf morphology. However, this species differs by the length of stipule (6–9 mm long in E. sobraleanum vs. 2.5–4.2 mm in E. oxypetalum ), short shoots (present vs. absent); margin of young stipule (markedly fimbriolate vs. entire) and length of pedicels (3–4.5 vs. 2–2.5 mm). E. oxypetalum is registered from central and northeastern Minas Gerais ( Plowman 1987, Loiola & Costa-Lima 2014), and the two species are allopatric. The new species is also similar in general branching appearance to E. caatingae Plowman (1987: 5) also of sect. Archerythroxylum, differing by the branchlets (flexuous in E. sobraleanum vs. rigid in E. caatingae ), leaf texture (membranaceous vs. firmly chartaceaous, subcoriaceous) and calyx lobe shape (triangular vs. ovate to lanceolate). E. caatinga grows in caatinga vegetation ( Plowman 1987, Loiola & Costa-Lima 2014) in northeast Brazil (Bahia, Ceará, Paraíba, Pernambuco, Piauí, Rio Grande do Norte, Sergipe). Other morphological differences between these three species are listed in Table 1 .

Figures

FIGURE 1. Erythroxylum sobraleanum. A. General appearance of a branch. B. Leaf. C. Stipule, frontal view. D. Detail of a branch showing stipules and flowers. E. Petals. F. Dolichostylous flower (a petal was removed). A–C (from Sobral 14248 HUFSJ); D–F (from Silveira et al. s.n. CESJ 30636); drawn by Francisco Átila Leles Magalhães).

FIGURE 2. Erythroxylum sobraleanum. A. General appearance of a branch. B. Detail of a branch showing stipules and flowers (Pictures by Marcos Sobral).

FIGURE 3. Geographic distribution of Erythroxylum sobraleanum.