Alcantarea compacta, a new species from the grasslands on rocky soils of Minas Gerais State.
Subject: Bromeliaceae (Natural history)
Authors: Leme, Elton M.C.
Ribeiro, Otavio B.de C.
Pub Date: 11/01/2010
Publication: Name: Journal of the Bromeliad Society Publisher: Bromeliad Society International Audience: Academic Format: Magazine/Journal Subject: Biological sciences Copyright: COPYRIGHT 2010 Bromeliad Society International ISSN: 0090-8738
Issue: Date: Nov-Dec, 2010 Source Volume: 60 Source Issue: 6
Geographic: Geographic Scope: Brazil Geographic Code: 3BRAZ Brazil
Accession Number: 257434797
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Alcantarea is a comparatively small-sized tillandsioid genus comprising some 30 known species. It is endemic to Brazil and lives in rocky environments that stretch from the north coastal region of Sao Paulo state, Southeastern Brazil--the southernmost limit, with 1 taxon or 3.7% of the species--to the Northeastern state of Bahia--the Northernmost limit, with 2 taxa or 7.4% of the species. The diversity center of the genus is concentrated in the southeastern states of Rio de Janeiro (with 12 taxa or 44.4% of the species), Minas Gerais (with 11 taxa or 40.7% of the species) and EspIrito Santo (with 6 taxa or 22.2% of the species).

The species of Alcantarea are exclusively saxicolous or rupicolous, living mostly in sun-exposed areas in rocky escarpments in the domain of the Atlantic Forest (with 23 taxa or 85% of the species). A few species, like A. burlemarxii (Leme) J.R. Grant, A. duarteana (L.B. Sm.) J.R. Grant, A. hatschbachii (L.B. Sm.& R.W Read) Leme, and A. turgida Versieux & Wand., grow in outcrops in the grasslands on rocky soils or "Campos Rupestres" that form the usually high-altitude landscape of the Serra do Espinhaco range, standing out from the savannas domain in Minas Gerais state. The new species described below is an addition to the "Campos Rupestres" flora.

Alcantarea compacta Leme & O. B. C. Ribeiro, sp. nov. Type: Brazil, Minas Gerais, Santana do Pirapama, near the border with Congonhas do Norte, Vale do Barbado, 1,207 m elev., 18[degrees]53'05"S 43[degrees]45'04"W, ca. 26 Nov. 2010, E. Leme 8478, O. Ribeiro, R. Oliveira & C. Oliveira (Holotype: RB, Isotype: HB).

Ab A. duarteana (L.B. Sm.) J.R. Grant, cui affinis, laminis foliorum brevioribus latioribusque, apice acuminatis, bracteis pedunculi supernis ovato-lanceolatis acuminatis, brevioribus, inflorescentia breviore et bracteis floriferis orbicularibus latioribusque differt.

Plant rupicolous, stemless, flowering 60-80 cm high. Leaves 17 to 20 in number, coriaceous, densely rosulate, suberect, forming a funnelform rosette; sheaths ovate, 12-17 x 9.5-10 cm, inconspicuously lepidote, green toward the apex, strongly coriaceous; blades narrowly subtriangular-lanceolate, not narrowed at the base, 15-24 x 5-6 cm, green, inconspicously and sparsely white-lepidote mainly adaxially to glabrous, nerved, suberect with recurved apex, apex acuminate. Peduncle 30-45 cm long, 0.8-1 cm in diameter, erect, glabrous, green; peduncle bracts: the basal ones subfoliaceous, the upper ones ovate-lanceolate, acuminate, suberect toward the apex, its basal portion enfolding the scape and without any notable water-holding capacity, distinctly exceeding the internodes, 7.5-8 x 2.5-3 cm, completely green or more often red toward the base and green at the apex, glabrous, covered by a oleaginous substance. Inflorescence shortly paniculate, densely bipinnate, 22-30 cm long (including the terminal branch), 11-13 cm in diameter, erect, rachis nearly straight, green, glabrous, 0.5-0.7 cm in diameter, internodes 1.5-3 cm long; primary bracts distinctly exceeding the stipes but all shorter than the branches, without notable water-holding capacity, the basal ones resembling the upper scape bracts, the upper ones broadly ovate to orbicular, apex acute and apiculate, 2.5-4.5 x 2.5-3 cm, suberect, glabrous abaxially, inconspicuously and sparsely white lepidote adaxially, covered by an oleaginous substance, completely green or red at the base and green toward the apex; branches 10 to 12 in number (including the terminal one), 1.5-3 cm apart, the lateral branches 6-9 cm long, erect or nearly so at the base and subspreading toward the apex, subdensely to densely flowered at anthesis, with 4 to 6 flowers, bearing sterile bracts at the apex, rachis geniculate, slightly angulose, 3-8 x 3 mm, glabrous, green, stipes 7-30 x 5 mm, erect or nearly so, slightly complanate, green, glabrous, ebracteate, the terminal branch erect or nearly so, similar to the lateral branches, subsessile, ca. 8-flowered; floral bracts orbicular or nearly so, 20-27 x 25-27 mm, apex rounded, incurved and appearing cucullate, greenish-yellow toward the apex and yellowish-green at the base, glabrous or nearly so, equaling 1/2 of the sepals length, strongly convex, carinate or the upper ones obtusely if at all carinate, covered by an oleaginous substance. Flowers distichous, divergent, not secund, slightly fragrant, 70-86 mm long (with extended petals), covered by an oleaginous substance, pedicels 7-9 x 6 mm, subcylindrical, green, glabrous; sepals slightly asymmetric, obovate, apex rounded, 25-29 x 12-15 mm, glabrous, free, ecarinate, green at the base and yellowish-green toward the apex, cymbiform, thinly coriaceous, covered by an oleaginous substance; petals sublinear, apex obtuse-emarginate, 60-79 x 7.5 mm, golden yellow, strongly spirally recurved at anthesis, completely exposing the stamens, becoming pendent-flaccidescent afterwards, bearing at the base 2 linear, obtuse to irregularly bidentate, 10-17 x 1.5 mm appendages adnate to the petals for 8-12 mm; stamens completely exposed at anthesis, erect; filaments terete, white, the antesepalous ones free, the antepetalous ones shortly adnate to the petals; anthers linear, 8-10 mm long, filiform at anthesis, fixed near the base, distinctly shorter than the petals; pollen narrowly ellipsoid, sulcate, exine broadly reticulate, lumina subrounded, muri narrowed; style slightly shorter than the petals, white; stigma conduplicate-spreading, blades slightly contorted with recurved apices, densely papillose, white, ca. 1.5 mm long. Capsules unknown.

Paratype: Brazil, Minas Gerais, Congonhas do Norte, on the border with Santana do Pirapama, border of the plateau, ca. 1,450 m elev., 18[degrees]53'00"S 43[degrees]43'27"W 18 Sept. 2010, E. Leme 8446, J. A. Siqueira Filho & O. Ribeiro (RB).

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Alcantarea compacta is morphologically related to A. duarteana which grows in the neighbouring county of Diamantina. However, A. compaicta differs from it by the shorter (15-24 cm vs. 60-70 cm long) and broader (5-6 cm vs. 3-4 cm wide at the base) leaf blades with acuminate apex (vs. long attenuate-caudate), ovate-lanceolate and acuminate upper peduncle bracts (vs. foliaceous, narrowly triangular, long-attenuate and caudate) which are shorter (7.5-8 cm vs. 20-30 cm long), shorter inflorescence (22-30 cm vs. 40-45 cm long) and by the orbicular floral bracts (vs. ovate), which are broader 25-27 mm vs. 20-21 mm wide).

The epithet of this new species is a reference to its compact leaf rosette due to the comparatively shorter and densely rosulate leaves, which is a striking distinctive character of A. compacta.

Alcantarea compacta was discovered as a rupicolous species in the "Campos Rupestres" outcrops at the border of the counties of Santana do Pirapama and Congonhas do Norte, not far from the well known Serra do Cipo National Park. It lives in completely sun-exposed sites along higher and steep parts of the plateau border, ca. 1,400 m high, as well as on less inclined rocky surfaces along the internal valleys, ca. 1,200 high. Individuals are sparsely distributed in the species range, with adult specimens producing abundant basal adventitious offsets, which is a characteristic for the genus (Leme, 2007). Other species observed sharing the same environment are Aechmea bromeliifolia (Rudge) Baker, Dyckia sp., Encholirium subsecundum (Baker) Mez, Tillandsia streptocarpa Baker, Vriesea oligantha (Baker) Mez, to name few, as well as other conspicuous species like Barbacenia sp. (Velloziaceae), Cattleya caulescens (Lindl.) H.G. Jones, and Pilosocereus aurisetus (Werderm.) Byles & G.D. Rowley (Cactaceae).

Acknowledgements

We thank the botanist Jose Alves Siqueira Filho and the Secretary of Culture of the Prefecture of Congonhas do Norte, Cloves Oliveira, and Rafael de Oliveira for their valuable field support and companionship during the expeditions to Congonhas do Norte and Santana do Pirapama.

Literature cited

Leme, E. M. C. (2007) Improving Taxa and Character Sampling to Support Generic Status of Alcantarea. J. Bromeliad Soc., 57, 208-215.

E.M.C. Leme: Herbarium Bradeanum, Rio de Janeiro--RJ, leme@tjrj.jus.br Otavio B. de C Ribeiro: Unidade de Pesquisa e Conservacao de Bromeliaceae--UPCB, Departamento de Biologia Vegetal, Universidade Federal de Vicosa, CEP 36570-000, Vicosa, MG, Brazil. E-mail: otaviocacto@vicosa.ufv.br
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