Plant saxicolous, short caulescent, flowering 0.8-1.4m high, propagating by basal shoots.
Leaves ca. 15 in number, suberect; densely arranged in a funnelform rosette.
Sheaths broadly ovate, 12-17 x 9-10.5 cm, pale brown becoming soft green toward apex abaxially, whitish becoming greenish adaxially, densely brown lepidote on both sides.
Blades sublinear, apex cuspidate, 24-42 x 4.5-6 cm, lustrous, green on both surfaces, with a narrow (i.e., ca. 0.8 mm wide) dark wine-colored line along the margins, glabrous, involute, suberect with recurved apices, coriaceous, distinctly nerved, weakly plicate in cross section.
Scape 60-75 cm long, exceeding the rosette, with 4.5-7 cm long internodes, 1.3-1.7 cm diam., pale green underneath the bracts but dark wine-colored at exposed portions, glabrescent, distinctly nerved, slightly curved.
Scape Bracts the proximal ones subfoliaceous, the distal ones ovate, apex long-attenuate and slightly recurved, 8-14 x 3-3.6cm, densely white lepidote and totally green becoming purple toward apex adaxially, sparsely lepidote and deep purple becoming greenish with purplish-red dots toward apex abaxially, margins with a very narrow purple line all along, involute, suberect, densely imbticate, the basal 1/3 firmly concealing the scape, distinctly nerved with some prominent veins, weakly plicate in cross section.
Inflorescence once branched, elliptic in outline, 46-54 x 23-26cm, main axis with 34 cm long internodes.
Flowering Branches laxly to subdensely arranged, 4-12 in number, 6-14 flowered, pendulous to arcuate, some of them distinctly tortuous or somewhat twisted.
Rachis geniculate, almost quadrangular in cross section, 8-20 cm long, 4 mm diam., green, glabrous, with 2.7 (proximal) to 1.2 cm (distal) long internodes separating the flowers.
Primary Bracts broadly ovate, 5-6 x 3.2-3.6 cm, apiculate, slightly inflated, dark wine-colored at the insertion line, along the margins and toward the apex, and greenish in the central portion, distinctly nerved, lepidote.
Peduncles flattened, elliptic in cross section, 4-9 cm long, 7mm diam. at the base, green, glabrous, bearing 1-2 sterile bracts.
Sterile Bracts broadly ovate, shortly attenuate, 3-4.2 x 2.5-3.5 cm, purplish green, glabrous or nearly so, symmetric, carinate.
Floral Bracts broadly ovate, apex obtuse, 2.8-3.6 x 2.5-2.8 cm, glabrous or nearly so, green with few purple spots along the margins, symmetric, membranaceous, carinate toward the apex.
Pedicels obconic, 4-6 mm long, 45 mm diam., green.
Flowers odorless, not secund.
Sepals elliptic, apex acute, 3.5-3.8 x 1.2-1.8 cm, equaling the floral bracts to exceeding them for ca. 2 mm, free, symmetric, glabrescent, green, ecarinate.
Petals long-linear with an acute apex, golden-yellow, inconspicuously whitish at the base, recoiling and spiraling, 5.7-6 x 0.6-0.7 cm, free, symmetric, glabrous.
Petal Appendages 2, ligulate, 14-20 x 1-2 mm, longitudinally adnate to the petals for 1.1-1.6 cm.
Stamens free.
Filaments terete, slightly flattened, 5.2-5.5 cm long, ca. 1mm thick, white.
Anthers sagittate, 1.2-1.5 cm long, ca. 1 mm thick, dorsifixed near the base, rimose.
Style terete, white, 7.5-7.7 cm long, ca. l mm diam.
Stigma lobes white, ca. 3 x 1 mm, erect.
Ovary ca. 11 x 3-4 mm, ovate, hypanthium ca. 5 mm in length.
Ovules numerous, ca. 1.4 mm long, with an elliptic apical appendage, restricted to the upper 1/2 portion of the ovary.
Fruits and Seeds unknown.

Type: Brazil. Rio de Janeiro: Santa Maria Madalena, afloramento rochoso proximo ao pico da pedra do Desengano, 21°53'59"S, 41°54'40.2"W, 1900m, 25 Nov 2005, Versieux & Calvente 240 (holotype: SP). (Figs. 2, 3)

Distribution and ecology.
Alcantarea tortuosa grows as a heliophyte on bare rocks above 1900m together with Alcantarea farneyi (Martinelli & And. Costa) J. R. Grant and Vellozia variegata Goeth. & Henrard near the peak of the main inselberg of the Desengano State Park, Rio de Janeiro state, Brazil. It has only been registered from this park, where it grows inside a unique habitat known as campo de altitude (i.e., high altitude grassland), which is associated with the Atlantic rain forest domain and is very rich in endemic species (Martinelli, 1989). Based on the IUCN criteria (IUCN, 2001), A. tortuosa can be included in the conservation status of Endangered EN B l ab(iii) due to its restricted area of occurrence, small population size, and projected decline in the quality of its habitat, since it grows right along the trail leading to the Desengano peak.

Phenology. In floral bud during November, blooming from December to January.

Etymology. It is named after the shape of the scape and of the inflorescence, which is tortuous.

Additional specimen examined. BRAZIL. Rio De Janeiro: Santa Maria Madalena, afloramento rochoso proximo ao pico da pedra do Dosengano, 21°53'59"S, 41°54'40.2"W 1900m. 25 Nov 2005, Versieux & Calvente 241 (SP).

Alcantarea tortuosa is probably related to A. farneyi, but its unique set of characters sets it apart from all other members of the genus. Future molecular work should indicate better its taxonomic relationships.
Although both species are sympatric, and the blooming periods almost overlap, A. farneyi exhibits a graminoid habit, forming a subbulbous rosette, with very narrow (i.e., ca. 1.5 cm wide) and involute leaves, ecarinate floral bracts, and a simple, pendulous, and shorter (ca. 11 cm) inflorescence.
On the other hand, A. tortuosa has a funnelform rosette that accumulates water, much wider leaf blades, floral bracts carinate toward the apex, and a branched and longer inflorescence.
The similarities between these two species reside in the presence of very narrow dark red margins along the leaf blades, coloration and imbrication of bracts, and in some floral characters such as the size of the sepals, the petals, and the petal appendages.
Alcantarea tortuosa can also be distinguished from A. benzingii Leme, a species that occurs in similar habitat in Espirito Santo state, and that was described as being closely related to A. farneyi. Alcantarea tortuosa is recognized by the size and shape of its scape, which is much thicker and tortuous (vs. slender and suberect), by the distinct coloration of its deep reddish-purple bracts (vs. reddish-yellow), by the size and type of the inflorescence, which is, branched (vs. shorter and simple inflorescence), by the size and type of the rosette, and by its wider blades.